review.tizen.org Git - platform/kernel/linux-rpi.git/log

KVM: LAPIC: Reduce world switch latency caused by timer_advance_ns

All the checks in lapic_timer_int_injected(), __kvm_wait_lapic_expire(), and
these function calls waste cpu cycles when the timer mode is not tscdeadline.
We can observe ~1.3% world switch time overhead by kvm-unit-tests/vmexit.flat
vmcall testing on AMD server. This patch reduces the world switch latency
caused by timer_advance_ns feature when the timer mode is not tscdeadline by
simpling move the check against apic->lapic_timer.expired_tscdeadline much
earlier.

Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1599731444-3525-7-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: LAPIC: Narrow down the kick target vCPU

The kick after setting KVM_REQ_PENDING_TIMER is used to handle the timer
fires on a different pCPU which vCPU is running on. This kick costs about
1000 clock cycles and we don't need this when injecting already-expired
timer or when using the VMX preemption timer because
kvm_lapic_expired_hv_timer() is called from the target vCPU.

Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1599731444-3525-6-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: LAPIC: Guarantee the timer is in tsc-deadline mode when setting

Check apic_lvtt_tscdeadline() mode directly instead of apic_lvtt_oneshot()
and apic_lvtt_period() to guarantee the timer is in tsc-deadline mode when
wrmsr MSR_IA32_TSCDEADLINE.

Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1599731444-3525-3-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: LAPIC: Return 0 when getting the tscdeadline timer if the lapic is hw disabled

Return 0 when getting the tscdeadline timer if the lapic is hw disabled.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1599731444-3525-2-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: LAPIC: Fix updating DFR missing apic map recalculation

There is missing apic map recalculation after updating DFR, if it is
INIT RESET, in x2apic mode, local apic is software enabled before.
This patch fix it by introducing the function kvm_apic_set_dfr() to
be called in INIT RESET handling path.

Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1597827327-25055-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

kvm/eventfd: move wildcard calculation outside loop

There is no need to calculate wildcard in each iteration
since wildcard is not changed.

Signed-off-by: Yi Li <yili@winhong.com>
Message-Id: <20200911055652.3041762-1-yili@winhong.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: nVMX: Simplify the initialization of nested_vmx_msrs

The nested VMX controls MSRs can be initialized by the global capability
values stored in vmcs_config.

Signed-off-by: Chenyi Qiang <chenyi.qiang@intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Message-Id: <20200828085622.8365-6-chenyi.qiang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: nVMX: Fix VMX controls MSRs setup when nested VMX enabled

KVM supports the nested VM_{EXIT, ENTRY}_LOAD_IA32_PERF_GLOBAL_CTRL and
VM_{ENTRY_LOAD, EXIT_CLEAR}_BNDCFGS, but they are not exposed by the
system ioctl KVM_GET_MSR. Add them to the setup of nested VMX controls MSR.

Signed-off-by: Chenyi Qiang <chenyi.qiang@intel.com>
Message-Id: <20200828085622.8365-2-chenyi.qiang@intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: nSVM: Avoid freeing uninitialized pointers in svm_set_nested_state()

The save and ctl pointers are passed uninitialized to kfree() when
svm_set_nested_state() follows the 'goto out_set_gif' path. While the
issue could've been fixed by initializing these on-stack varialbles to
NULL, it seems preferable to eliminate 'out_set_gif' label completely as
it is not actually a failure path and duplicating a single svm_set_gif()
call doesn't look too bad.

[ bp: Drop obscure Addresses-Coverity: tag. ]

Fixes: 6ccbd29ade0d ("KVM: SVM: nested: Don't allocate VMCB structures on stack")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reported-by: Joerg Roedel <jroedel@suse.de>
Reported-by: Colin King <colin.king@canonical.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Acked-by: Joerg Roedel <jroedel@suse.de>
Tested-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lkml.kernel.org/r/20200914133725.650221-1-vkuznets@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Merge tag 'kvm-ppc-next-5.10-1' of git://git./linux/kernel/git/paulus/powerpc into HEAD

PPC KVM update for 5.10

- Fix for running nested guests with in-kernel IRQ chip
- Fix race condition causing occasional host hard lockup
- Minor cleanups and bugfixes

Merge branch 'x86-seves-for-paolo' of https://git./linux/kernel/git/tip/tip into HEAD

KVM: PPC: Book3S: Fix symbol undeclared warnings

Build the kernel with `C=2`:
arch/powerpc/kvm/book3s_hv_nested.c:572:25: warning: symbol
'kvmhv_alloc_nested' was not declared. Should it be static?
arch/powerpc/kvm/book3s_64_mmu_radix.c:350:6: warning: symbol
'kvmppc_radix_set_pte_at' was not declared. Should it be static?
arch/powerpc/kvm/book3s_hv.c:3568:5: warning: symbol
'kvmhv_p9_guest_entry' was not declared. Should it be static?
arch/powerpc/kvm/book3s_hv_rm_xics.c:767:15: warning: symbol 'eoi_rc'
was not declared. Should it be static?
arch/powerpc/kvm/book3s_64_vio_hv.c:240:13: warning: symbol
'iommu_tce_kill_rm' was not declared. Should it be static?
arch/powerpc/kvm/book3s_64_vio.c:492:6: warning: symbol
'kvmppc_tce_iommu_do_map' was not declared. Should it be static?
arch/powerpc/kvm/book3s_pr.c:572:6: warning: symbol 'kvmppc_set_pvr_pr'
was not declared. Should it be static?

Those symbols are used only in the files that define them so make them
static to fix the warnings.

Signed-off-by: Wang Wensheng <wangwensheng4@huawei.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

KVM: PPC: Book3S: Remove redundant initialization of variable ret

The variable ret is being initialized with '-ENOMEM' that is meaningless.
So remove it.

Signed-off-by: Jing Xiangfeng <jingxiangfeng@huawei.com>
Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

KVM: PPC: Book3S HV: XIVE: Convert to DEFINE_SHOW_ATTRIBUTE

Use DEFINE_SHOW_ATTRIBUTE macro to simplify the code.

Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

Merge tag 'kvm-s390-master-5.9-1' of git://git./linux/kernel/git/kvms390/linux into kvm-master

KVM: s390: add documentation for KVM_CAP_S390_DIAG318

diag318 code was merged in 5.9-rc1, let us add some
missing documentation

Merge tag 'kvmarm-fixes-5.9-2' of git://git./linux/kernel/git/kvmarm/kvmarm into kvm-master

KVM/arm64 fixes for 5.9, take #2

- Fix handling of S1 Page Table Walk permission fault at S2
on instruction fetch
- Cleanup kvm_vcpu_dabt_iswrite()

Revert "KVM: Check the allocation of pv cpu mask"

The commit 0f990222108d ("KVM: Check the allocation of pv cpu mask") we
have in 5.9-rc5 has two issue:
1) Compilation fails for !CONFIG_SMP, see:
https://bugzilla.kernel.org/show_bug.cgi?id=209285

2) This commit completely disables PV TLB flush, see
https://lore.kernel.org/kvm/87y2lrnnyf.fsf@vitty.brq.redhat.com/

The allocation problem is likely a theoretical one, if we don't
have memory that early in boot process we're likely doomed anyway.
Let's solve it properly later.

This reverts commit 0f990222108d214a0924d920e6095b58107d7b59.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: arm64: Remove S1PTW check from kvm_vcpu_dabt_iswrite()

Now that kvm_vcpu_trap_is_write_fault() checks for S1PTW, there
is no need for kvm_vcpu_dabt_iswrite() to do the same thing, as
we already check for this condition on all existing paths.

Drop the check and add a comment instead.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20200915104218.1284701-3-maz@kernel.org

KVM: arm64: Assume write fault on S1PTW permission fault on instruction fetch

KVM currently assumes that an instruction abort can never be a write.
This is in general true, except when the abort is triggered by
a S1PTW on instruction fetch that tries to update the S1 page tables
(to set AF, for example).

This can happen if the page tables have been paged out and brought
back in without seeing a direct write to them (they are thus marked
read only), and the fault handling code will make the PT executable(!)
instead of writable. The guest gets stuck forever.

In these conditions, the permission fault must be considered as
a write so that the Stage-1 update can take place. This is essentially
the I-side equivalent of the problem fixed by 60e21a0ef54c ("arm64: KVM:
Take S1 walks into account when determining S2 write faults").

Update kvm_is_write_fault() to return true on IABT+S1PTW, and introduce
kvm_vcpu_trap_is_exec_fault() that only return true when no faulting
on a S1 fault. Additionally, kvm_vcpu_dabt_iss1tw() is renamed to
kvm_vcpu_abt_iss1tw(), as the above makes it plain that it isn't
specific to data abort.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Will Deacon <will@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200915104218.1284701-2-maz@kernel.org

KVM: PPC: Book3S HV: Set LPCR[HDICE] before writing HDEC

POWER8 and POWER9 machines have a hardware deviation where generation
of a hypervisor decrementer exception is suppressed if the HDICE bit
in the LPCR register is 0 at the time when the HDEC register
decrements from 0 to -1.  When entering a guest, KVM first writes the
HDEC register with the time until it wants the CPU to exit the guest,
and then writes the LPCR with the guest value, which includes
HDICE = 1.  If HDEC decrements from 0 to -1 during the interval
between those two events, it is possible that we can enter the guest
with HDEC already negative but no HDEC exception pending, meaning that
no HDEC interrupt will occur while the CPU is in the guest, or at
least not until HDEC wraps around.  Thus it is possible for the CPU to
keep executing in the guest for a long time; up to about 4 seconds on
POWER8, or about 4.46 years on POWER9 (except that the host kernel
hard lockup detector will fire first).

To fix this, we set the LPCR[HDICE] bit before writing HDEC on guest
entry.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

KVM: PPC: Book3S HV: Do not allocate HPT for a nested guest

The current nested KVM code does not support HPT guests. This is
informed/enforced in some ways:

- Hosts < P9 will not be able to enable the nested HV feature;

- The nested hypervisor MMU capabilities will not contain
  KVM_CAP_PPC_MMU_HASH_V3;

- QEMU reflects the MMU capabilities in the
  'ibm,arch-vec-5-platform-support' device-tree property;

- The nested guest, at 'prom_parse_mmu_model' ignores the
  'disable_radix' kernel command line option if HPT is not supported;

- The KVM_PPC_CONFIGURE_V3_MMU ioctl will fail if trying to use HPT.

There is, however, still a way to start a HPT guest by using
max-compat-cpu=power8 at the QEMU machine options. This leads to the
guest being set to use hash after QEMU calls the KVM_PPC_ALLOCATE_HTAB
ioctl.

With the guest set to hash, the nested hypervisor goes through the
entry path that has no knowledge of nesting (kvmppc_run_vcpu) and
crashes when it tries to execute an hypervisor-privileged (mtspr
HDEC) instruction at __kvmppc_vcore_entry:

root@L1:~ $ qemu-system-ppc64 -machine pseries,max-cpu-compat=power8 ...

<snip>
[  538.543303] CPU: 83 PID: 25185 Comm: CPU 0/KVM Not tainted 5.9.0-rc4 #1
[  538.543355] NIP:  c00800000753f388 LR: c00800000753f368 CTR: c0000000001e5ec0
[  538.543417] REGS: c0000013e91e33b0 TRAP: 0700   Not tainted  (5.9.0-rc4)
[  538.543470] MSR:  8000000002843033 <SF,VEC,VSX,FP,ME,IR,DR,RI,LE>  CR: 22422882  XER: 20040000
[  538.543546] CFAR: c00800000753f4b0 IRQMASK: 3
               GPR00: c0080000075397a0 c0000013e91e3640 c00800000755e600 0000000080000000
               GPR04: 0000000000000000 c0000013eab19800 c000001394de0000 00000043a054db72
               GPR08: 00000000003b1652 0000000000000000 0000000000000000 c0080000075502e0
               GPR12: c0000000001e5ec0 c0000007ffa74200 c0000013eab19800 0000000000000008
               GPR16: 0000000000000000 c00000139676c6c0 c000000001d23948 c0000013e91e38b8
               GPR20: 0000000000000053 0000000000000000 0000000000000001 0000000000000000
               GPR24: 0000000000000001 0000000000000001 0000000000000000 0000000000000001
               GPR28: 0000000000000001 0000000000000053 c0000013eab19800 0000000000000001
[  538.544067] NIP [c00800000753f388] __kvmppc_vcore_entry+0x90/0x104 [kvm_hv]
[  538.544121] LR [c00800000753f368] __kvmppc_vcore_entry+0x70/0x104 [kvm_hv]
[  538.544173] Call Trace:
[  538.544196] [c0000013e91e3640] [c0000013e91e3680] 0xc0000013e91e3680 (unreliable)
[  538.544260] [c0000013e91e3820] [c0080000075397a0] kvmppc_run_core+0xbc8/0x19d0 [kvm_hv]
[  538.544325] [c0000013e91e39e0] [c00800000753d99c] kvmppc_vcpu_run_hv+0x404/0xc00 [kvm_hv]
[  538.544394] [c0000013e91e3ad0] [c0080000072da4fc] kvmppc_vcpu_run+0x34/0x48 [kvm]
[  538.544472] [c0000013e91e3af0] [c0080000072d61b8] kvm_arch_vcpu_ioctl_run+0x310/0x420 [kvm]
[  538.544539] [c0000013e91e3b80] [c0080000072c7450] kvm_vcpu_ioctl+0x298/0x778 [kvm]
[  538.544605] [c0000013e91e3ce0] [c0000000004b8c2c] sys_ioctl+0x1dc/0xc90
[  538.544662] [c0000013e91e3dc0] [c00000000002f9a4] system_call_exception+0xe4/0x1c0
[  538.544726] [c0000013e91e3e20] [c00000000000d140] system_call_common+0xf0/0x27c
[  538.544787] Instruction dump:
[  538.544821] f86d1098 60000000 60000000 48000099 e8ad0fe8 e8c500a0 e9264140 75290002
[  538.544886] 7d1602a6 7cec42a6 40820008 7d0807b4 <7d164ba6> 7d083a14 f90d10a0 480104fd
[  538.544953] ---[ end trace 74423e2b948c2e0c ]---

This patch makes the KVM_PPC_ALLOCATE_HTAB ioctl fail when running in
the nested hypervisor, causing QEMU to abort.

Reported-by: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
Signed-off-by: Fabiano Rosas <farosas@linux.ibm.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

KVM: PPC: Don't return -ENOTSUPP to userspace in ioctls

ENOTSUPP is a linux only thingy, the value of which is unknown to
userspace, not to be confused with ENOTSUP which linux maps to
EOPNOTSUPP, as permitted by POSIX [1]:

[EOPNOTSUPP]
Operation not supported on socket. The type of socket (address family
or protocol) does not support the requested operation. A conforming
implementation may assign the same values for [EOPNOTSUPP] and [ENOTSUP].

Return -EOPNOTSUPP instead of -ENOTSUPP for the following ioctls:
- KVM_GET_FPU for Book3s and BookE
- KVM_SET_FPU for Book3s and BookE
- KVM_GET_DIRTY_LOG for BookE

This doesn't affect QEMU which doesn't call the KVM_GET_FPU and
KVM_SET_FPU ioctls on POWER anyway since they are not supported,
and _buggily_ ignores anything but -EPERM for KVM_GET_DIRTY_LOG.

[1] https://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html

Signed-off-by: Greg Kurz <groug@kaod.org>
Acked-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

docs: kvm: add documentation for KVM_CAP_S390_DIAG318

Documentation for the s390 DIAGNOSE 0x318 instruction handling.

Signed-off-by: Collin Walling <walling@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/kvm/20200625150724.10021-2-walling@linux.ibm.com/
Message-Id: <20200625150724.10021-2-walling@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

KVM: emulator: more strict rsm checks.

Don't ignore return values in rsm_load_state_64/32 to avoid
loading invalid state from SMM state area if it was tampered with
by the guest.

This is primarly intended to avoid letting guest set bits in EFER
(like EFER.SVME when nesting is disabled) by manipulating SMM save area.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20200827171145.374620-8-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: nSVM: more strict SMM checks when returning to nested guest

* check that guest is 64 bit guest, otherwise the SVM related fields
  in the smm state area are not defined

* If the SMM area indicates that SMM interrupted a running guest,
  check that EFER.SVME which is also saved in this area is set, otherwise
  the guest might have tampered with SMM save area, and so indicate
  emulation failure which should triple fault the guest.

* Check that that guest CPUID supports SVM (due to the same issue as above)

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20200827162720.278690-4-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

SVM: nSVM: setup nested msr permission bitmap on nested state load

This code was missing and was forcing the L2 run with L1's msr
permission bitmap

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20200827162720.278690-3-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

SVM: nSVM: correctly restore GIF on vmexit from nesting after migration

Currently code in svm_set_nested_state copies the current vmcb control
area to L1 control area (hsave->control), under assumption that
it mostly reflects the defaults that kvm choose, and later qemu
overrides  these defaults with L2 state using standard KVM interfaces,
like KVM_SET_REGS.

However nested GIF (which is AMD specific thing) is by default is true,
and it is copied to hsave area as such.

This alone is not a big deal since on VMexit, GIF is always set to false,
regardless of what it was on VM entry.  However in nested_svm_vmexit we
were first were setting GIF to false, but then we overwrite the control
fields with value from the hsave area.  (including the nested GIF field
itself if GIF virtualization is enabled).

Now on normal vm entry this is not a problem, since GIF is usually false
prior to normal vm entry, and this is the value that copied to hsave,
and then restored, but this is not always the case when the nested state
is loaded as explained above.

To fix this issue, move svm_set_gif after we restore the L1 control
state in nested_svm_vmexit, so that even with wrong GIF in the
saved L1 control area, we still clear GIF as the spec says.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20200827162720.278690-2-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

x86/kvm: don't forget to ACK async PF IRQ

Merge commit 26d05b368a5c0 ("Merge branch 'kvm-async-pf-int' into HEAD")
tried to adapt the new interrupt based async PF mechanism to the newly
introduced IDTENTRY magic but unfortunately it missed the fact that
DEFINE_IDTENTRY_SYSVEC() doesn't call ack_APIC_irq() on its own and
all DEFINE_IDTENTRY_SYSVEC() users have to call it manually.

As the result all multi-CPU KVM guest hang on boot when
KVM_FEATURE_ASYNC_PF_INT is present. The breakage went unnoticed because no
KVM userspace (e.g. QEMU) currently set it (and thus async PF mechanism
is currently disabled) but we're about to change that.

Fixes: 26d05b368a5c0 ("Merge branch 'kvm-async-pf-int' into HEAD")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200908135350.355053-3-vkuznets@redhat.com>
Tested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

x86/kvm: properly use DEFINE_IDTENTRY_SYSVEC() macro

DEFINE_IDTENTRY_SYSVEC() already contains irqentry_enter()/
irqentry_exit().

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200908135350.355053-2-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: VMX: Don't freeze guest when event delivery causes an APIC-access exit

According to SDM 27.2.4, Event delivery causes an APIC-access VM exit.
Don't report internal error and freeze guest when event delivery causes
an APIC-access exit, it is handleable and the event will be re-injected
during the next vmentry.

Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1597827327-25055-2-git-send-email-wanpengli@tencent.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: SVM: avoid emulation with stale next_rip

svm->next_rip is reset in svm_vcpu_run() only after calling
svm_exit_handlers_fastpath(), which will cause SVM's
skip_emulated_instruction() to write a stale RIP.

We can move svm_exit_handlers_fastpath towards the end of
svm_vcpu_run(). To align VMX with SVM, keep svm_complete_interrupts()
close as well.

Suggested-by: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Paul K. <kronenpj@kronenpj.dyndns.org>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
[Also move vmcb_mark_all_clean before any possible write to the VMCB.
- Paolo]

KVM: x86: always allow writing '0' to MSR_KVM_ASYNC_PF_EN

Even without in-kernel LAPIC we should allow writing '0' to
MSR_KVM_ASYNC_PF_EN as we're not enabling the mechanism. In
particular, QEMU with 'kernel-irqchip=off' fails to start
a guest with

qemu-system-x86_64: error: failed to set MSR 0x4b564d02 to 0x0

Fixes: 9d3c447c72fb2 ("KVM: X86: Fix async pf caused null-ptr-deref")
Reported-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200911093147.484565-1-vkuznets@redhat.com>
[Actually commit the version proposed by Sean Christopherson. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: SVM: Periodically schedule when unregistering regions on destroy

There may be many encrypted regions that need to be unregistered when a
SEV VM is destroyed. This can lead to soft lockups. For example, on a
host running 4.15:

watchdog: BUG: soft lockup - CPU#206 stuck for 11s! [t_virtual_machi:194348]
CPU: 206 PID: 194348 Comm: t_virtual_machi
RIP: 0010:free_unref_page_list+0x105/0x170
...
Call Trace:
[<0>] release_pages+0x159/0x3d0
[<0>] sev_unpin_memory+0x2c/0x50 [kvm_amd]
[<0>] __unregister_enc_region_locked+0x2f/0x70 [kvm_amd]
[<0>] svm_vm_destroy+0xa9/0x200 [kvm_amd]
[<0>] kvm_arch_destroy_vm+0x47/0x200
[<0>] kvm_put_kvm+0x1a8/0x2f0
[<0>] kvm_vm_release+0x25/0x30
[<0>] do_exit+0x335/0xc10
[<0>] do_group_exit+0x3f/0xa0
[<0>] get_signal+0x1bc/0x670
[<0>] do_signal+0x31/0x130

Although the CLFLUSH is no longer issued on every encrypted region to be
unregistered, there are no other changes that can prevent soft lockups for
very large SEV VMs in the latest kernel.

Periodically schedule if necessary. This still holds kvm->lock across the
resched, but since this only happens when the VM is destroyed this is
assumed to be acceptable.

Signed-off-by: David Rientjes <rientjes@google.com>
Message-Id: <alpine.DEB.2.23.453.2008251255240.2987727@chino.kir.corp.google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: MIPS: Change the definition of kvm type

MIPS defines two kvm types:

#define KVM_VM_MIPS_TE          0
#define KVM_VM_MIPS_VZ          1

In Documentation/virt/kvm/api.rst it is said that "You probably want to
use 0 as machine type", which implies that type 0 be the "automatic" or
"default" type. And, in user-space libvirt use the null-machine (with
type 0) to detect the kvm capability, which returns "KVM not supported"
on a VZ platform.

I try to fix it in QEMU but it is ugly:
https://lists.nongnu.org/archive/html/qemu-devel/2020-08/msg05629.html

And Thomas Huth suggests me to change the definition of kvm type:
https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg03281.html

So I define like this:

#define KVM_VM_MIPS_AUTO        0
#define KVM_VM_MIPS_VZ          1
#define KVM_VM_MIPS_TE          2

Since VZ and TE cannot co-exists, using type 0 on a TE platform will
still return success (so old user-space tools have no problems on new
kernels); the advantage is that using type 0 on a VZ platform will not
return failure. So, the only problem is "new user-space tools use type
2 on old kernels", but if we treat this as a kernel bug, we can backport
this patch to old stable kernels.

Signed-off-by: Huacai Chen <chenhc@lemote.com>
Message-Id: <1599734031-28746-1-git-send-email-chenhc@lemote.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

kvm x86/mmu: use KVM_REQ_MMU_SYNC to sync when needed

When kvm_mmu_get_page() gets a page with unsynced children, the spt
pagetable is unsynchronized with the guest pagetable. But the
guest might not issue a "flush" operation on it when the pagetable
entry is changed from zero or other cases. The hypervisor has the
responsibility to synchronize the pagetables.

KVM behaved as above for many years, But commit 8c8560b83390
("KVM: x86/mmu: Use KVM_REQ_TLB_FLUSH_CURRENT for MMU specific flushes")
inadvertently included a line of code to change it without giving any
reason in the changelog. It is clear that the commit's intention was to
change KVM_REQ_TLB_FLUSH -> KVM_REQ_TLB_FLUSH_CURRENT, so we don't
needlessly flush other contexts; however, one of the hunks changed
a nearby KVM_REQ_MMU_SYNC instead. This patch changes it back.

Link: https://lore.kernel.org/lkml/20200320212833.3507-26-sean.j.christopherson@intel.com/
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20200902135421.31158-1-jiangshanlai@gmail.com>
fixes: 8c8560b83390 ("KVM: x86/mmu: Use KVM_REQ_TLB_FLUSH_CURRENT for MMU specific flushes")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: nVMX: Fix the update value of nested load IA32_PERF_GLOBAL_CTRL control

A minor fix for the update of VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL field
in exit_ctls_high.

Fixes: 03a8871add95 ("KVM: nVMX: Expose load IA32_PERF_GLOBAL_CTRL
VM-{Entry,Exit} control")
Signed-off-by: Chenyi Qiang <chenyi.qiang@intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Message-Id: <20200828085622.8365-5-chenyi.qiang@intel.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: fix memory leak in kvm_io_bus_unregister_dev()

when kmalloc() fails in kvm_io_bus_unregister_dev(), before removing
the bus, we should iterate over all other devices linked to it and call
kvm_iodevice_destructor() for them

Fixes: 90db10434b16 ("KVM: kvm_io_bus_unregister_dev() should never fail")
Cc: stable@vger.kernel.org
Reported-and-tested-by: syzbot+f196caa45793d6374707@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?extid=f196caa45793d6374707
Signed-off-by: Rustam Kovhaev <rkovhaev@gmail.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200907185535.233114-1-rkovhaev@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: Check the allocation of pv cpu mask

check the allocation of per-cpu __pv_cpu_mask. Initialize ops only when
successful.

Signed-off-by: Haiwei Li <lihaiwei@tencent.com>
Message-Id: <d59f05df-e6d3-3d31-a036-cc25a2b2f33f@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: nVMX: Update VMCS02 when L2 PAE PDPTE updates detected

When L2 uses PAE, L0 intercepts of L2 writes to CR0/CR3/CR4 call
load_pdptrs to read the possibly updated PDPTEs from the guest
physical address referenced by CR3. It loads them into
vcpu->arch.walk_mmu->pdptrs and sets VCPU_EXREG_PDPTR in
vcpu->arch.regs_dirty.

At the subsequent assumed reentry into L2, the mmu will call
vmx_load_mmu_pgd which calls ept_load_pdptrs. ept_load_pdptrs sees
VCPU_EXREG_PDPTR set in vcpu->arch.regs_dirty and loads
VMCS02.GUEST_PDPTRn from vcpu->arch.walk_mmu->pdptrs[]. This all works
if the L2 CRn write intercept always resumes L2.

The resume path calls vmx_check_nested_events which checks for
exceptions, MTF, and expired VMX preemption timers. If
vmx_check_nested_events finds any of these conditions pending it will
reflect the corresponding exit into L1. Live migration at this point
would also cause a missed immediate reentry into L2.

After L1 exits, vmx_vcpu_run calls vmx_register_cache_reset which
clears VCPU_EXREG_PDPTR in vcpu->arch.regs_dirty. When L2 next
resumes, ept_load_pdptrs finds VCPU_EXREG_PDPTR clear in
vcpu->arch.regs_dirty and does not load VMCS02.GUEST_PDPTRn from
vcpu->arch.walk_mmu->pdptrs[]. prepare_vmcs02 will then load
VMCS02.GUEST_PDPTRn from vmcs12->pdptr0/1/2/3 which contain the stale
values stored at last L2 exit. A repro of this bug showed L2 entering
triple fault immediately due to the bad VMCS02.GUEST_PDPTRn values.

When L2 is in PAE paging mode add a call to ept_load_pdptrs before
leaving L2. This will update VMCS02.GUEST_PDPTRn if they are dirty in
vcpu->arch.walk_mmu->pdptrs[].

Tested:
kvm-unit-tests with new directed test: vmx_mtf_pdpte_test.
Verified that test fails without the fix.

Also ran Google internal VMM with an Ubuntu 16.04 4.4.0-83 guest running a
custom hypervisor with a 32-bit Windows XP L2 guest using PAE. Prior to fix
would repro readily. Ran 14 simultaneous L2s for 140 iterations with no
failures.

Signed-off-by: Peter Shier <pshier@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Message-Id: <20200820230545.2411347-1-pshier@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Merge tag 'kvmarm-fixes-5.9-1' of git://git./linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 fixes for Linux 5.9, take #1

- Multiple stolen time fixes, with a new capability to match x86
- Fix for hugetlbfs mappings when PUD and PMD are the same level
- Fix for hugetlbfs mappings when PTE mappings are enforced
(dirty logging, for example)
- Fix tracing output of 64bit values

KVM: SVM: Use __packed shorthand

Use the shorthand to make it more readable.

No functional changes.

Signed-off-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200907131613.12703-5-joro@8bytes.org

KVM: SVM: Add GHCB Accessor functions

Building a correct GHCB for the hypervisor requires setting valid bits
in the GHCB. Simplify that process by providing accessor functions to
set values and to update the valid bitmap and to check the valid bitmap
in KVM.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200907131613.12703-4-joro@8bytes.org

KVM: SVM: Add GHCB definitions

Extend the vmcb_safe_area with SEV-ES fields and add a new
'struct ghcb' which will be used for guest-hypervisor communication.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200907131613.12703-3-joro@8bytes.org

KVM: SVM: nested: Don't allocate VMCB structures on stack

Do not allocate a vmcb_control_area and a vmcb_save_area on the stack,
as these structures will become larger with future extenstions of
SVM and thus the svm_set_nested_state() function will become a too large
stack frame.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200907131613.12703-2-joro@8bytes.org

Merge 'x86/cpu' to pick up dependent bits

Pick up work happening in parallel to avoid nasty merge conflicts later.

Signed-off-by: Borislav Petkov <bp@suse.de>

Merge 'x86/kaslr' to pick up dependent bits

Signed-off-by: Borislav Petkov <bp@suse.de>

Linux 5.9-rc4

Merge tag 'io_uring-5.9-2020-09-06' of git://git.kernel.dk/linux-block

Pull more io_uring fixes from Jens Axboe:
"Two followup fixes. One is fixing a regression from this merge window,
  the other is two commits fixing cancelation of deferred requests.

  Both have gone through full testing, and both spawned a few new
  regression test additions to liburing.

   - Don't play games with const, properly store the output iovec and
     assign it as needed.

   - Deferred request cancelation fix (Pavel)"

* tag 'io_uring-5.9-2020-09-06' of git://git.kernel.dk/linux-block:
  io_uring: fix linked deferred ->files cancellation
  io_uring: fix cancel of deferred reqs with ->files
  io_uring: fix explicit async read/write mapping for large segments

Merge tag 'iommu-fixes-v5.9-rc3' of git://git./linux/kernel/git/joro/iommu

Pull iommu fixes from Joerg Roedel:

- three Intel VT-d fixes to fix address handling on 32bit, fix a NULL
   pointer dereference bug and serialize a hardware register access as
   required by the VT-d spec.

- two patches for AMD IOMMU to force AMD GPUs into translation mode
   when memory encryption is active and disallow using IOMMUv2
   functionality.  This makes the AMDGPU driver work when memory
   encryption is active.

- two more fixes for AMD IOMMU to fix updating the Interrupt Remapping
   Table Entries.

- MAINTAINERS file update for the Qualcom IOMMU driver.

* tag 'iommu-fixes-v5.9-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu:
  iommu/vt-d: Handle 36bit addressing for x86-32
  iommu/amd: Do not use IOMMUv2 functionality when SME is active
  iommu/amd: Do not force direct mapping when SME is active
  iommu/amd: Use cmpxchg_double() when updating 128-bit IRTE
  iommu/amd: Restore IRTE.RemapEn bit after programming IRTE
  iommu/vt-d: Fix NULL pointer dereference in dev_iommu_priv_set()
  iommu/vt-d: Serialize IOMMU GCMD register modifications
  MAINTAINERS: Update QUALCOMM IOMMU after Arm SMMU drivers move

Merge tag 'x86-urgent-2020-09-06' of git://git./linux/kernel/git/tip/tip

Pull x86 fixes from Ingo Molnar:

- more generic entry code ABI fallout

- debug register handling bugfixes

- fix vmalloc mappings on 32-bit kernels

- kprobes instrumentation output fix on 32-bit kernels

- fix over-eager WARN_ON_ONCE() on !SMAP hardware

- NUMA debugging fix

- fix Clang related crash on !RETPOLINE kernels

* tag 'x86-urgent-2020-09-06' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/entry: Unbreak 32bit fast syscall
  x86/debug: Allow a single level of #DB recursion
  x86/entry: Fix AC assertion
  tracing/kprobes, x86/ptrace: Fix regs argument order for i386
  x86, fakenuma: Fix invalid starting node ID
  x86/mm/32: Bring back vmalloc faulting on x86_32
  x86/cmdline: Disable jump tables for cmdline.c

Merge tag 'for-linus-5.9-rc4-tag' of git://git./linux/kernel/git/xen/tip

Pull xen updates from Juergen Gross:
"A small series for fixing a problem with Xen PVH guests when running
  as backends (e.g. as dom0).

  Mapping other guests' memory is now working via ZONE_DEVICE, thus not
  requiring to abuse the memory hotplug functionality for that purpose"

* tag 'for-linus-5.9-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen: add helpers to allocate unpopulated memory
  memremap: rename MEMORY_DEVICE_DEVDAX to MEMORY_DEVICE_GENERIC
  xen/balloon: add header guard

io_uring: fix linked deferred ->files cancellation

While looking for ->files in ->defer_list, consider that requests there
may actually be links.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: fix cancel of deferred reqs with ->files

While trying to cancel requests with ->files, it also should look for
requests in ->defer_list, otherwise it might end up hanging a thread.

Cancel all requests in ->defer_list up to the last request there with
matching ->files, that's needed to follow drain ordering semantics.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Merge tags 'auxdisplay-for-linus-v5.9-rc4', 'clang-format-for-linus-v5.9-rc4' and 'compiler-attributes-for-linus-v5.9-rc4' of git://github.com/ojeda/linux

Pull misc fixes from Miguel Ojeda:
"A trivial patch for auxdisplay:

   - Replace HTTP links with HTTPS ones (Alexander A. Klimov)

  The usual clang-format trivial update:

   - Update with the latest for_each macro list (Miguel Ojeda)

  And Luc requested me to pick a sparse fix on my queue, so here it goes
  along with other two trivial Compiler Attributes ones (also from Luc).

   - sparse: use static inline for __chk_{user,io}_ptr() (Luc Van
     Oostenryck)

   - Compiler Attributes: fix comment concerning GCC 4.6 (Luc Van
     Oostenryck)

   - Compiler Attributes: remove comment about sparse not supporting
     __has_attribute (Luc Van Oostenryck)"

* tag 'auxdisplay-for-linus-v5.9-rc4' of git://github.com/ojeda/linux:
  auxdisplay: Replace HTTP links with HTTPS ones

* tag 'clang-format-for-linus-v5.9-rc4' of git://github.com/ojeda/linux:
  clang-format: Update with the latest for_each macro list

* tag 'compiler-attributes-for-linus-v5.9-rc4' of git://github.com/ojeda/linux:
  sparse: use static inline for __chk_{user,io}_ptr()
  Compiler Attributes: fix comment concerning GCC 4.6
  Compiler Attributes: remove comment about sparse not supporting __has_attribute

Merge tag 'arc-5.9-rc4' of git://git./linux/kernel/git/vgupta/arc

Pull ARC fixes from Vineet Gupta:

- HSDK-4xd Dev system: perf driver updates for sampling interrupt

- HSDK* Dev System: Ethernet broken [Evgeniy Didin]

- HIGHMEM broken (2 memory banks) [Mike Rapoport]

- show_regs() rewrite once and for all

- Other minor fixes

* tag 'arc-5.9-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc:
  ARC: [plat-hsdk]: Switch ethernet phy-mode to rgmii-id
  arc: fix memory initialization for systems with two memory banks
  irqchip/eznps: Fix build error for !ARC700 builds
  ARC: show_regs: fix r12 printing and simplify
  ARC: HSDK: wireup perf irq
  ARC: perf: don't bail setup if pct irq missing in device-tree
  ARC: pgalloc.h: delete a duplicated word + other fixes

Merge branch 'akpm' (patches from Andrew)

Merge misc fixes from Andrew Morton:
"19 patches.

  Subsystems affected by this patch series: MAINTAINERS, ipc, fork,
  checkpatch, lib, and mm (memcg, slub, pagemap, madvise, migration,
  hugetlb)"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  include/linux/log2.h: add missing () around n in roundup_pow_of_two()
  mm/khugepaged.c: fix khugepaged's request size in collapse_file
  mm/hugetlb: fix a race between hugetlb sysctl handlers
  mm/hugetlb: try preferred node first when alloc gigantic page from cma
  mm/migrate: preserve soft dirty in remove_migration_pte()
  mm/migrate: remove unnecessary is_zone_device_page() check
  mm/rmap: fixup copying of soft dirty and uffd ptes
  mm/migrate: fixup setting UFFD_WP flag
  mm: madvise: fix vma user-after-free
  checkpatch: fix the usage of capture group ( ... )
  fork: adjust sysctl_max_threads definition to match prototype
  ipc: adjust proc_ipc_sem_dointvec definition to match prototype
  mm: track page table modifications in __apply_to_page_range()
  MAINTAINERS: IA64: mark Status as Odd Fixes only
  MAINTAINERS: add LLVM maintainers
  MAINTAINERS: update Cavium/Marvell entries
  mm: slub: fix conversion of freelist_corrupted()
  mm: memcg: fix memcg reclaim soft lockup
  memcg: fix use-after-free in uncharge_batch

include/linux/log2.h: add missing () around n in roundup_pow_of_two()

Otherwise gcc generates warnings if the expression is complicated.

Fixes: 312a0c170945 ("[PATCH] LOG2: Alter roundup_pow_of_two() so that it can use a ilog2() on a constant")
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.kernel.org/r/0-v1-8a2697e3c003+41165-log_brackets_jgg@nvidia.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/khugepaged.c: fix khugepaged's request size in collapse_file

collapse_file() in khugepaged passes PAGE_SIZE as the number of pages to
be read to page_cache_sync_readahead(). The intent was probably to read
a single page. Fix it to use the number of pages to the end of the
window instead.

Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Yang Shi <shy828301@gmail.com>
Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Eric Biggers <ebiggers@google.com>
Link: https://lkml.kernel.org/r/20200903140844.14194-2-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/hugetlb: fix a race between hugetlb sysctl handlers

There is a race between the assignment of `table->data` and write value
to the pointer of `table->data` in the __do_proc_doulongvec_minmax() on
the other thread.

  CPU0:                                 CPU1:
                                        proc_sys_write
  hugetlb_sysctl_handler                  proc_sys_call_handler
  hugetlb_sysctl_handler_common             hugetlb_sysctl_handler
    table->data = &tmp;                       hugetlb_sysctl_handler_common
                                                table->data = &tmp;
      proc_doulongvec_minmax
        do_proc_doulongvec_minmax           sysctl_head_finish
          __do_proc_doulongvec_minmax         unuse_table
            i = table->data;
            *i = val;  // corrupt CPU1's stack

Fix this by duplicating the `table`, and only update the duplicate of
it.  And introduce a helper of proc_hugetlb_doulongvec_minmax() to
simplify the code.

The following oops was seen:

    BUG: kernel NULL pointer dereference, address: 0000000000000000
    #PF: supervisor instruction fetch in kernel mode
    #PF: error_code(0x0010) - not-present page
    Code: Bad RIP value.
    ...
    Call Trace:
     ? set_max_huge_pages+0x3da/0x4f0
     ? alloc_pool_huge_page+0x150/0x150
     ? proc_doulongvec_minmax+0x46/0x60
     ? hugetlb_sysctl_handler_common+0x1c7/0x200
     ? nr_hugepages_store+0x20/0x20
     ? copy_fd_bitmaps+0x170/0x170
     ? hugetlb_sysctl_handler+0x1e/0x20
     ? proc_sys_call_handler+0x2f1/0x300
     ? unregister_sysctl_table+0xb0/0xb0
     ? __fd_install+0x78/0x100
     ? proc_sys_write+0x14/0x20
     ? __vfs_write+0x4d/0x90
     ? vfs_write+0xef/0x240
     ? ksys_write+0xc0/0x160
     ? __ia32_sys_read+0x50/0x50
     ? __close_fd+0x129/0x150
     ? __x64_sys_write+0x43/0x50
     ? do_syscall_64+0x6c/0x200
     ? entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fixes: e5ff215941d5 ("hugetlb: multiple hstates for multiple page sizes")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/20200828031146.43035-1-songmuchun@bytedance.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/hugetlb: try preferred node first when alloc gigantic page from cma

Since commit cf11e85fc08c ("mm: hugetlb: optionally allocate gigantic
hugepages using cma"), the gigantic page would be allocated from node
which is not the preferred node, although there are pages available from
that node. The reason is that the nid parameter has been ignored in
alloc_gigantic_page().

Besides, the __GFP_THISNODE also need be checked if user required to
alloc only from the preferred node.

After this patch, the preferred node is tried first before other allowed
nodes, and don't try to allocate from other nodes if __GFP_THISNODE is
specified. If user don't specify the preferred node, the current node
will be used as preferred node, which makes sure consistent behavior of
allocating gigantic and non-gigantic hugetlb page.

Fixes: cf11e85fc08c ("mm: hugetlb: optionally allocate gigantic hugepages using cma")
Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Link: https://lkml.kernel.org/r/20200902025016.697260-1-lixinhai.lxh@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/migrate: preserve soft dirty in remove_migration_pte()

The code to remove a migration PTE and replace it with a device private
PTE was not copying the soft dirty bit from the migration entry. This
could lead to page contents not being marked dirty when faulting the page
back from device private memory.

Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Bharata B Rao <bharata@linux.ibm.com>
Link: https://lkml.kernel.org/r/20200831212222.22409-3-rcampbell@nvidia.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/migrate: remove unnecessary is_zone_device_page() check

Patch series "mm/migrate: preserve soft dirty in remove_migration_pte()".

I happened to notice this from code inspection after seeing Alistair
Popple's patch ("mm/rmap: Fixup copying of soft dirty and uffd ptes").

This patch (of 2):

The check for is_zone_device_page() and is_device_private_page() is
unnecessary since the latter is sufficient to determine if the page is a
device private page. Simplify the code for easier reading.

Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Bharata B Rao <bharata@linux.ibm.com>
Link: https://lkml.kernel.org/r/20200831212222.22409-1-rcampbell@nvidia.com
Link: https://lkml.kernel.org/r/20200831212222.22409-2-rcampbell@nvidia.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/rmap: fixup copying of soft dirty and uffd ptes

During memory migration a pte is temporarily replaced with a migration
swap pte. Some pte bits from the existing mapping such as the soft-dirty
and uffd write-protect bits are preserved by copying these to the
temporary migration swap pte.

However these bits are not stored at the same location for swap and
non-swap ptes. Therefore testing these bits requires using the
appropriate helper function for the given pte type.

Unfortunately several code locations were found where the wrong helper
function is being used to test soft_dirty and uffd_wp bits which leads to
them getting incorrectly set or cleared during page-migration.

Fix these by using the correct tests based on pte type.

Fixes: a5430dda8a3a ("mm/migrate: support un-addressable ZONE_DEVICE page in migration")
Fixes: 8c3328f1f36a ("mm/migrate: migrate_vma() unmap page from vma while collecting pages")
Fixes: f45ec5ff16a7 ("userfaultfd: wp: support swap and page migration")
Signed-off-by: Alistair Popple <alistair@popple.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Peter Xu <peterx@redhat.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Alistair Popple <alistair@popple.id.au>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20200825064232.10023-2-alistair@popple.id.au
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/migrate: fixup setting UFFD_WP flag

Commit f45ec5ff16a75 ("userfaultfd: wp: support swap and page migration")
introduced support for tracking the uffd wp bit during page migration.
However the non-swap PTE variant was used to set the flag for zone device
private pages which are a type of swap page.

This leads to corruption of the swap offset if the original PTE has the
uffd_wp flag set.

Fixes: f45ec5ff16a75 ("userfaultfd: wp: support swap and page migration")
Signed-off-by: Alistair Popple <alistair@popple.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Peter Xu <peterx@redhat.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Link: https://lkml.kernel.org/r/20200825064232.10023-1-alistair@popple.id.au
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: madvise: fix vma user-after-free

The syzbot reported the below use-after-free:

  BUG: KASAN: use-after-free in madvise_willneed mm/madvise.c:293 [inline]
  BUG: KASAN: use-after-free in madvise_vma mm/madvise.c:942 [inline]
  BUG: KASAN: use-after-free in do_madvise.part.0+0x1c8b/0x1cf0 mm/madvise.c:1145
  Read of size 8 at addr ffff8880a6163eb0 by task syz-executor.0/9996

  CPU: 0 PID: 9996 Comm: syz-executor.0 Not tainted 5.9.0-rc1-syzkaller #0
  Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
  Call Trace:
    __dump_stack lib/dump_stack.c:77 [inline]
    dump_stack+0x18f/0x20d lib/dump_stack.c:118
    print_address_description.constprop.0.cold+0xae/0x497 mm/kasan/report.c:383
    __kasan_report mm/kasan/report.c:513 [inline]
    kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
    madvise_willneed mm/madvise.c:293 [inline]
    madvise_vma mm/madvise.c:942 [inline]
    do_madvise.part.0+0x1c8b/0x1cf0 mm/madvise.c:1145
    do_madvise mm/madvise.c:1169 [inline]
    __do_sys_madvise mm/madvise.c:1171 [inline]
    __se_sys_madvise mm/madvise.c:1169 [inline]
    __x64_sys_madvise+0xd9/0x110 mm/madvise.c:1169
    do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
    entry_SYSCALL_64_after_hwframe+0x44/0xa9

  Allocated by task 9992:
    kmem_cache_alloc+0x138/0x3a0 mm/slab.c:3482
    vm_area_alloc+0x1c/0x110 kernel/fork.c:347
    mmap_region+0x8e5/0x1780 mm/mmap.c:1743
    do_mmap+0xcf9/0x11d0 mm/mmap.c:1545
    vm_mmap_pgoff+0x195/0x200 mm/util.c:506
    ksys_mmap_pgoff+0x43a/0x560 mm/mmap.c:1596
    do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
    entry_SYSCALL_64_after_hwframe+0x44/0xa9

  Freed by task 9992:
    kmem_cache_free.part.0+0x67/0x1f0 mm/slab.c:3693
    remove_vma+0x132/0x170 mm/mmap.c:184
    remove_vma_list mm/mmap.c:2613 [inline]
    __do_munmap+0x743/0x1170 mm/mmap.c:2869
    do_munmap mm/mmap.c:2877 [inline]
    mmap_region+0x257/0x1780 mm/mmap.c:1716
    do_mmap+0xcf9/0x11d0 mm/mmap.c:1545
    vm_mmap_pgoff+0x195/0x200 mm/util.c:506
    ksys_mmap_pgoff+0x43a/0x560 mm/mmap.c:1596
    do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
    entry_SYSCALL_64_after_hwframe+0x44/0xa9

It is because vma is accessed after releasing mmap_lock, but someone
else acquired the mmap_lock and the vma is gone.

Releasing mmap_lock after accessing vma should fix the problem.

Fixes: 692fe62433d4c ("mm: Handle MADV_WILLNEED through vfs_fadvise()")
Reported-by: syzbot+b90df26038d1d5d85c97@syzkaller.appspotmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: <stable@vger.kernel.org> [5.4+]
Link: https://lkml.kernel.org/r/20200816141204.162624-1-shy828301@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

checkpatch: fix the usage of capture group ( ... )

The usage of "capture group (...)" in the immediate condition after `&&`
results in `$1` being uninitialized.  This issues a warning "Use of
uninitialized value $1 in regexp compilation at ./scripts/checkpatch.pl
line 2638".

I noticed this bug while running checkpatch on the set of commits from
v5.7 to v5.8-rc1 of the kernel on the commits with a diff content in
their commit message.

This bug was introduced in the script by commit e518e9a59ec3
("checkpatch: emit an error when there's a diff in a changelog").  It
has been in the script since then.

The author intended to store the match made by capture group in variable
`$1`.  This should have contained the name of the file as `[\w/]+`
matched.  However, this couldn't be accomplished due to usage of capture
group and `$1` in the same regular expression.

Fix this by placing the capture group in the condition before `&&`.
Thus, `$1` can be initialized to the text that capture group matches
thereby setting it to the desired and required value.

Fixes: e518e9a59ec3 ("checkpatch: emit an error when there's a diff in a changelog")
Signed-off-by: Mrinal Pandey <mrinalmni@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Reviewed-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: Joe Perches <joe@perches.com>
Link: https://lkml.kernel.org/r/20200714032352.f476hanaj2dlmiot@mrinalpandey
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fork: adjust sysctl_max_threads definition to match prototype

Commit 32927393dc1c ("sysctl: pass kernel pointers to ->proc_handler")
changed ctl_table.proc_handler to take a kernel pointer.  Adjust the
definition of sysctl_max_threads to match its prototype in
linux/sysctl.h which fixes the following sparse error/warning:

  kernel/fork.c:3050:47: warning: incorrect type in argument 3 (different address spaces)
  kernel/fork.c:3050:47:    expected void *
  kernel/fork.c:3050:47:    got void [noderef] __user *buffer
  kernel/fork.c:3036:5: error: symbol 'sysctl_max_threads' redeclared with different type (incompatible argument 3 (different address spaces)):
  kernel/fork.c:3036:5:    int extern [addressable] [signed] [toplevel] sysctl_max_threads( ... )
  kernel/fork.c: note: in included file (through include/linux/key.h, include/linux/cred.h, include/linux/sched/signal.h, include/linux/sched/cputime.h):
  include/linux/sysctl.h:242:5: note: previously declared as:
  include/linux/sysctl.h:242:5:    int extern [addressable] [signed] [toplevel] sysctl_max_threads( ... )

Fixes: 32927393dc1c ("sysctl: pass kernel pointers to ->proc_handler")
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lkml.kernel.org/r/20200825093647.24263-1-tklauser@distanz.ch
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

ipc: adjust proc_ipc_sem_dointvec definition to match prototype

Commit 32927393dc1c ("sysctl: pass kernel pointers to ->proc_handler")
changed ctl_table.proc_handler to take a kernel pointer.  Adjust the
signature of proc_ipc_sem_dointvec to match ctl_table.proc_handler which
fixes the following sparse error/warning:

  ipc/ipc_sysctl.c:94:47: warning: incorrect type in argument 3 (different address spaces)
  ipc/ipc_sysctl.c:94:47:    expected void *buffer
  ipc/ipc_sysctl.c:94:47:    got void [noderef] __user *buffer
  ipc/ipc_sysctl.c:194:35: warning: incorrect type in initializer (incompatible argument 3 (different address spaces))
  ipc/ipc_sysctl.c:194:35:    expected int ( [usertype] *proc_handler )( ... )
  ipc/ipc_sysctl.c:194:35:    got int ( * )( ... )

Fixes: 32927393dc1c ("sysctl: pass kernel pointers to ->proc_handler")
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Link: https://lkml.kernel.org/r/20200825105846.5193-1-tklauser@distanz.ch
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: track page table modifications in __apply_to_page_range()

__apply_to_page_range() is also used to change and/or allocate
page-table pages in the vmalloc area of the address space.  Make sure
these changes get synchronized to other page-tables in the system by
calling arch_sync_kernel_mappings() when necessary.

The impact appears limited to x86-32, where apply_to_page_range may miss
updating the PMD.  That leads to explosions in drivers like

  BUG: unable to handle page fault for address: fe036000
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  *pde = 00000000
  Oops: 0002 [#1] SMP
  CPU: 3 PID: 1300 Comm: gem_concurrent_ Not tainted 5.9.0-rc1+ #16
  Hardware name:  /NUC6i3SYB, BIOS SYSKLi35.86A.0024.2015.1027.2142 10/27/2015
  EIP: __execlists_context_alloc+0x132/0x2d0 [i915]
  Code: 31 d2 89 f0 e8 2f 55 02 00 89 45 e8 3d 00 f0 ff ff 0f 87 11 01 00 00 8b 4d e8 03 4b 30 b8 5a 5a 5a 5a ba 01 00 00 00 8d 79 04 <c7> 01 5a 5a 5a 5a c7 81 fc 0f 00 00 5a 5a 5a 5a 83 e7 fc 29 f9 81
  EAX: 5a5a5a5a EBX: f60ca000 ECX: fe036000 EDX: 00000001
  ESI: f43b7340 EDI: fe036004 EBP: f6389cb8 ESP: f6389c9c
  DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 EFLAGS: 00010286
  CR0: 80050033 CR2: fe036000 CR3: 2d361000 CR4: 001506d0
  DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
  DR6: fffe0ff0 DR7: 00000400
  Call Trace:
    execlists_context_alloc+0x10/0x20 [i915]
    intel_context_alloc_state+0x3f/0x70 [i915]
    __intel_context_do_pin+0x117/0x170 [i915]
    i915_gem_do_execbuffer+0xcc7/0x2500 [i915]
    i915_gem_execbuffer2_ioctl+0xcd/0x1f0 [i915]
    drm_ioctl_kernel+0x8f/0xd0
    drm_ioctl+0x223/0x3d0
    __ia32_sys_ioctl+0x1ab/0x760
    __do_fast_syscall_32+0x3f/0x70
    do_fast_syscall_32+0x29/0x60
    do_SYSENTER_32+0x15/0x20
    entry_SYSENTER_32+0x9f/0xf2
  EIP: 0xb7f28559
  Code: 03 74 c0 01 10 05 03 74 b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d 76 00 58 b8 77 00 00 00 cd 80 90 8d 76
  EAX: ffffffda EBX: 00000005 ECX: c0406469 EDX: bf95556c
  ESI: b7e68000 EDI: c0406469 EBP: 00000005 ESP: bf9554d8
  DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 007b EFLAGS: 00000296
  Modules linked in: i915 x86_pkg_temp_thermal intel_powerclamp crc32_pclmul crc32c_intel intel_cstate intel_uncore intel_gtt drm_kms_helper intel_pch_thermal video button autofs4 i2c_i801 i2c_smbus fan
  CR2: 00000000fe036000

It looks like kasan, xen and i915 are vulnerable.

Actual impact is "on thinkpad X60 in 5.9-rc1, screen starts blinking
after 30-or-so minutes, and machine is unusable"

[sfr@canb.auug.org.au: ARCH_PAGE_TABLE_SYNC_MASK needs vmalloc.h]
Link: https://lkml.kernel.org/r/20200825172508.16800a4f@canb.auug.org.au
[chris@chris-wilson.co.uk: changelog addition]
[pavel@ucw.cz: changelog addition]

Fixes: 2ba3e6947aed ("mm/vmalloc: track which page-table levels were modified")
Fixes: 86cf69f1d893 ("x86/mm/32: implement arch_sync_kernel_mappings()")
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Chris Wilson <chris@chris-wilson.co.uk> [x86-32]
Tested-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: <stable@vger.kernel.org> [5.8+]
Link: https://lkml.kernel.org/r/20200821123746.16904-1-joro@8bytes.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

MAINTAINERS: IA64: mark Status as Odd Fixes only

IA64 isn't really being maintained, so mark it as Odd Fixes only.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Link: http://lkml.kernel.org/r/7e719139-450f-52c2-59a2-7964a34eda1f@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

MAINTAINERS: add LLVM maintainers

Nominate Nathan and myself to be point of contact for clang/LLVM related
support, after a poll at the LLVM BoF at Linux Plumbers Conf 2020.

While corporate sponsorship is beneficial, its important to not entrust
the keys to the nukes with any one entity. Should Nathan and I find
ourselves at the same employer, I would gladly step down.

Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com>
Acked-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Acked-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lkml.kernel.org/r/20200825143540.2948637-1-ndesaulniers@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

MAINTAINERS: update Cavium/Marvell entries

I am leaving Marvell and already do not have access to my @marvell.com
email address. So switching over to my korg mail address or removing my
address there another maintainer is already listed. For the entries
there no other maintainer is listed I will keep looking into patches for
Cavium systems for a while until someone from Marvell takes it over.

Since I might have limited access to hardware and also limited time I
changed state to 'Odd Fixes' for those entries.

Signed-off-by: Robert Richter <rric@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Ganapatrao Kulkarni <gkulkarni@marvell.com>
Cc: Sunil Goutham <sgoutham@marvell.com>
CC: Borislav Petkov <bp@alien8.de>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Wolfram Sang <wsa@kernel.org>,
Link: https://lkml.kernel.org/r/20200824122050.31164-1-rric@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: slub: fix conversion of freelist_corrupted()

Commit 52f23478081ae0 ("mm/slub.c: fix corrupted freechain in
deactivate_slab()") suffered an update when picked up from LKML [1].

Specifically, relocating 'freelist = NULL' into 'freelist_corrupted()'
created a no-op statement. Fix it by sticking to the behavior intended
in the original patch [1]. In addition, make freelist_corrupted()
immune to passing NULL instead of &freelist.

The issue has been spotted via static analysis and code review.

[1] https://lore.kernel.org/linux-mm/20200331031450.12182-1-dongli.zhang@oracle.com/

Fixes: 52f23478081ae0 ("mm/slub.c: fix corrupted freechain in deactivate_slab()")
Signed-off-by: Eugeniu Rosca <erosca@de.adit-jv.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Dongli Zhang <dongli.zhang@oracle.com>
Cc: Joe Jin <joe.jin@oracle.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20200824130643.10291-1-erosca@de.adit-jv.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: memcg: fix memcg reclaim soft lockup

We've met softlockup with "CONFIG_PREEMPT_NONE=y", when the target memcg
doesn't have any reclaimable memory.

It can be easily reproduced as below:

  watchdog: BUG: soft lockup - CPU#0 stuck for 111s![memcg_test:2204]
  CPU: 0 PID: 2204 Comm: memcg_test Not tainted 5.9.0-rc2+ #12
  Call Trace:
    shrink_lruvec+0x49f/0x640
    shrink_node+0x2a6/0x6f0
    do_try_to_free_pages+0xe9/0x3e0
    try_to_free_mem_cgroup_pages+0xef/0x1f0
    try_charge+0x2c1/0x750
    mem_cgroup_charge+0xd7/0x240
    __add_to_page_cache_locked+0x2fd/0x370
    add_to_page_cache_lru+0x4a/0xc0
    pagecache_get_page+0x10b/0x2f0
    filemap_fault+0x661/0xad0
    ext4_filemap_fault+0x2c/0x40
    __do_fault+0x4d/0xf9
    handle_mm_fault+0x1080/0x1790

It only happens on our 1-vcpu instances, because there's no chance for
oom reaper to run to reclaim the to-be-killed process.

Add a cond_resched() at the upper shrink_node_memcgs() to solve this
issue, this will mean that we will get a scheduling point for each memcg
in the reclaimed hierarchy without any dependency on the reclaimable
memory in that memcg thus making it more predictable.

Suggested-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Xunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Chris Down <chris@chrisdown.name>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Link: http://lkml.kernel.org/r/1598495549-67324-1-git-send-email-xlpang@linux.alibaba.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

memcg: fix use-after-free in uncharge_batch

syzbot has reported an use-after-free in the uncharge_batch path

  BUG: KASAN: use-after-free in instrument_atomic_write include/linux/instrumented.h:71 [inline]
  BUG: KASAN: use-after-free in atomic64_sub_return include/asm-generic/atomic-instrumented.h:970 [inline]
  BUG: KASAN: use-after-free in atomic_long_sub_return include/asm-generic/atomic-long.h:113 [inline]
  BUG: KASAN: use-after-free in page_counter_cancel mm/page_counter.c:54 [inline]
  BUG: KASAN: use-after-free in page_counter_uncharge+0x3d/0xc0 mm/page_counter.c:155
  Write of size 8 at addr ffff8880371c0148 by task syz-executor.0/9304

  CPU: 0 PID: 9304 Comm: syz-executor.0 Not tainted 5.8.0-syzkaller #0
  Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
  Call Trace:
    __dump_stack lib/dump_stack.c:77 [inline]
    dump_stack+0x1f0/0x31e lib/dump_stack.c:118
    print_address_description+0x66/0x620 mm/kasan/report.c:383
    __kasan_report mm/kasan/report.c:513 [inline]
    kasan_report+0x132/0x1d0 mm/kasan/report.c:530
    check_memory_region_inline mm/kasan/generic.c:183 [inline]
    check_memory_region+0x2b5/0x2f0 mm/kasan/generic.c:192
    instrument_atomic_write include/linux/instrumented.h:71 [inline]
    atomic64_sub_return include/asm-generic/atomic-instrumented.h:970 [inline]
    atomic_long_sub_return include/asm-generic/atomic-long.h:113 [inline]
    page_counter_cancel mm/page_counter.c:54 [inline]
    page_counter_uncharge+0x3d/0xc0 mm/page_counter.c:155
    uncharge_batch+0x6c/0x350 mm/memcontrol.c:6764
    uncharge_page+0x115/0x430 mm/memcontrol.c:6796
    uncharge_list mm/memcontrol.c:6835 [inline]
    mem_cgroup_uncharge_list+0x70/0xe0 mm/memcontrol.c:6877
    release_pages+0x13a2/0x1550 mm/swap.c:911
    tlb_batch_pages_flush mm/mmu_gather.c:49 [inline]
    tlb_flush_mmu_free mm/mmu_gather.c:242 [inline]
    tlb_flush_mmu+0x780/0x910 mm/mmu_gather.c:249
    tlb_finish_mmu+0xcb/0x200 mm/mmu_gather.c:328
    exit_mmap+0x296/0x550 mm/mmap.c:3185
    __mmput+0x113/0x370 kernel/fork.c:1076
    exit_mm+0x4cd/0x550 kernel/exit.c:483
    do_exit+0x576/0x1f20 kernel/exit.c:793
    do_group_exit+0x161/0x2d0 kernel/exit.c:903
    get_signal+0x139b/0x1d30 kernel/signal.c:2743
    arch_do_signal+0x33/0x610 arch/x86/kernel/signal.c:811
    exit_to_user_mode_loop kernel/entry/common.c:135 [inline]
    exit_to_user_mode_prepare+0x8d/0x1b0 kernel/entry/common.c:166
    syscall_exit_to_user_mode+0x5e/0x1a0 kernel/entry/common.c:241
    entry_SYSCALL_64_after_hwframe+0x44/0xa9

Commit 1a3e1f40962c ("mm: memcontrol: decouple reference counting from
page accounting") reworked the memcg lifetime to be bound the the struct
page rather than charges.  It also removed the css_put_many from
uncharge_batch and that is causing the above splat.

uncharge_batch() is supposed to uncharge accumulated charges for all
pages freed from the same memcg.  The queuing is done by uncharge_page
which however drops the memcg reference after it adds charges to the
batch.  If the current page happens to be the last one holding the
reference for its memcg then the memcg is OK to go and the next page to
be freed will trigger batched uncharge which needs to access the memcg
which is gone already.

Fix the issue by taking a reference for the memcg in the current batch.

Fixes: 1a3e1f40962c ("mm: memcontrol: decouple reference counting from page accounting")
Reported-by: syzbot+b305848212deec86eabe@syzkaller.appspotmail.com
Reported-by: syzbot+b5ea6fb6f139c8b9482b@syzkaller.appspotmail.com
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Hugh Dickins <hughd@google.com>
Link: https://lkml.kernel.org/r/20200820090341.GC5033@dhcp22.suse.cz
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Merge tag 'xfs-5.9-fixes-2' of git://git./fs/xfs/xfs-linux

Pull xfs fix from Darrick Wong:
"Fix a broken metadata verifier that would incorrectly validate attr
fork extents of a realtime file against the realtime volume"

* tag 'xfs-5.9-fixes-2' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
xfs: fix xfs_bmap_validate_extent_raw when checking attr fork of rt files

xfs: don't update mtime on COW faults

When running in a dax mode, if the user maps a page with MAP_PRIVATE and
PROT_WRITE, the xfs filesystem would incorrectly update ctime and mtime
when the user hits a COW fault.

This breaks building of the Linux kernel.  How to reproduce:

1. extract the Linux kernel tree on dax-mounted xfs filesystem
2. run make clean
3. run make -j12
4. run make -j12

at step 4, make would incorrectly rebuild the whole kernel (although it
was already built in step 3).

The reason for the breakage is that almost all object files depend on
objtool.  When we run objtool, it takes COW page fault on its .data
section, and these faults will incorrectly update the timestamp of the
objtool binary.  The updated timestamp causes make to rebuild the whole
tree.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

ext2: don't update mtime on COW faults

When running in a dax mode, if the user maps a page with MAP_PRIVATE and
PROT_WRITE, the ext2 filesystem would incorrectly update ctime and mtime
when the user hits a COW fault.

This breaks building of the Linux kernel.  How to reproduce:

1. extract the Linux kernel tree on dax-mounted ext2 filesystem
2. run make clean
3. run make -j12
4. run make -j12

at step 4, make would incorrectly rebuild the whole kernel (although it
was already built in step 3).

The reason for the breakage is that almost all object files depend on
objtool.  When we run objtool, it takes COW page fault on its .data
section, and these faults will incorrectly update the timestamp of the
objtool binary.  The updated timestamp causes make to rebuild the whole
tree.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

io_uring: fix explicit async read/write mapping for large segments

If we exceed UIO_FASTIOV, we don't handle the transition correctly
between an allocated vec for requests that are queued with IOSQE_ASYNC.
Store the iovec appropriately and re-set it in the iter iov in case
it changed.

Fixes: ff6165b2d7f6 ("io_uring: retain iov_iter state over io_read/io_write calls")
Reported-by: Nick Hill <nick@nickhill.org>
Tested-by: Norman Maurer <norman.maurer@googlemail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Merge tag 's390-5.9-5' of git://git./linux/kernel/git/s390/linux

Pull s390 fixes from Vasily Gorbik:

- Fix GENERIC_LOCKBREAK dependency on PREEMPTION in Kconfig broken
   because of a typo

- Update defconfigs

* tag 's390-5.9-5' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390: update defconfigs
  s390: fix GENERIC_LOCKBREAK dependency typo in Kconfig

Merge tag 'arm64-fixes' of git://git./linux/kernel/git/arm64/linux

Pull arm64 fixes from Catalin Marinas:

- Fix the loading of modules built with binutils-2.35. This version
   produces writable and executable .text.ftrace_trampoline section
   which is rejected by the kernel.

- Remove the exporting of cpu_logical_map() as the Tegra driver has now
   been fixed and no longer uses this function.

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64/module: set trampoline section flags regardless of CONFIG_DYNAMIC_FTRACE
  arm64: Remove exporting cpu_logical_map symbol

Merge tag 'mips_fixes_5.9_1' of git://git./linux/kernel/git/mips/linux

Pull MIPS fixes from Thomas Bogendoerfer:
"A few MIPS fixes:

   - fallthrough fallout fix

   - BMIPS fixes

   - MSA fix to avoid leaking MSA register contents

   - Loongson perf and cpu feature fix

   - SNI interrupt fix"

* tag 'mips_fixes_5.9_1' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux:
  MIPS: SNI: Fix SCSI interrupt
  MIPS: add missing MSACSR and upper MSA initialization
  MIPS: perf: Fix wrong check condition of Loongson event IDs
  mips/oprofile: Fix fallthrough placement
  MIPS: Loongson64: Remove unnecessary inclusion of boot_param.h
  MIPS: BMIPS: Also call bmips_cpu_setup() for secondary cores
  MIPS: mm: BMIPS5000 has inclusive physical caches
  MIPS: Loongson64: Do not override watch and ejtag feature

Merge tag 'kbuild-fixes-v5.9-2' of git://git./linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes from Masahiro Yamada:

- fix documents

- fix warning in 'make localmodconfig'

* tag 'kbuild-fixes-v5.9-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kconfig: remove redundant assignment prompt = prompt
  kbuild: Documentation: clean up makefiles.rst
  kconfig: streamline_config.pl: check defined(ENV variable) before using it
  Documentation/llvm: Improve formatting of commands, variables, and arguments

Merge tag 'pm-5.9-rc4' of git://git./linux/kernel/git/rafael/linux-pm

Pull power management fixes from Rafael Wysocki:
"These fix reference counting in the operating performance points (OPP)
  framework and address a few intel_pstate driver issues, mostly related
  to switching driver operation modes and similar with hardware-managed
  P-states (HWP) enabled.

  Specifics:

   - Fix reference counting of operating performance points (OPP) tables
     (Viresh Kumar).

   - Address intel_pstate driver interface issues, mostly related to
     switching operation modes and handling CPU offline and online and
     system-wide suspend/resume with hardware-managed P-states (HWP)
     enabled (Rafael Wysocki).

   - Fix the maximum frequency computation in the intel_pstate driver
     with turbo P-states disabled by the platform firmware and HWP
     enabled (Francisco Jerez)"

* tag 'pm-5.9-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  cpufreq: intel_pstate: Fix intel_pstate_get_hwp_max() for turbo disabled
  cpufreq: intel_pstate: Free memory only when turning off
  cpufreq: intel_pstate: Add ->offline and ->online callbacks
  cpufreq: intel_pstate: Tweak the EPP sysfs interface
  cpufreq: intel_pstate: Update cached EPP in the active mode
  cpufreq: intel_pstate: Refuse to turn off with HWP enabled
  opp: Don't drop reference for an OPP table that was never parsed

Merge tag 'libata-5.9-2020-09-04' of git://git.kernel.dk/linux-block

Pull libata fixes from Jens Axboe:

- improve Sandisks ATA_HORKAGE on NCQ (Tejun)

- link printk cleanup (Xu)

* tag 'libata-5.9-2020-09-04' of git://git.kernel.dk/linux-block:
libata: implement ATA_HORKAGE_MAX_TRIM_128M and apply to Sandisks
ata: ahci: use ata_link_info() instead of ata_link_printk()

Merge tag 'block-5.9-2020-09-04' of git://git.kernel.dk/linux-block

Pull block fixes from Jens Axboe:
"A bit larger than usual this week, mostly due to the NVMe fixes
  arriving late for -rc3 and hence didn't make last weeks pull request.

   - NVMe:
        - instance leak and io boundary fixes from Keith
        - fc locking fix from Christophe
        - various tcp/rdma reset during traffic fixes from Sagi
        - pci use-after-free fix from Tong
        - tcp target null deref fix from Ziye

   - Locking fix for partition removal (Christoph)

   - Ensure bdi->io_pages is always set (me)

   - Fixup for hd struct reference (Ming)

   - Fix for zero length bvecs (Ming)

   - Two small blk-iocost fixes (Tejun)"

* tag 'block-5.9-2020-09-04' of git://git.kernel.dk/linux-block:
  block: allow for_each_bvec to support zero len bvec
  blk-stat: make q->stats->lock irqsafe
  blk-iocost: ioc_pd_free() shouldn't assume irq disabled
  block: fix locking in bdev_del_partition
  block: release disk reference in hd_struct_free_work
  block: ensure bdi->io_pages is always initialized
  nvme-pci: cancel nvme device request before disabling
  nvme: only use power of two io boundaries
  nvme: fix controller instance leak
  nvmet-fc: Fix a missed _irqsave version of spin_lock in 'nvmet_fc_fod_op_done()'
  nvme: Fix NULL dereference for pci nvme controllers
  nvme-rdma: fix reset hang if controller died in the middle of a reset
  nvme-rdma: fix timeout handler
  nvme-rdma: serialize controller teardown sequences
  nvme-tcp: fix reset hang if controller died in the middle of a reset
  nvme-tcp: fix timeout handler
  nvme-tcp: serialize controller teardown sequences
  nvme: have nvme_wait_freeze_timeout return if it timed out
  nvme-fabrics: don't check state NVME_CTRL_NEW for request acceptance
  nvmet-tcp: Fix NULL dereference when a connect data comes in h2cdata pdu

Merge tag 'io_uring-5.9-2020-09-04' of git://git.kernel.dk/linux-block

Pull io_uring fixes from Jens Axboe:

- EAGAIN with O_NONBLOCK retry fix

- Two small fixes for registered files (Jiufei)

* tag 'io_uring-5.9-2020-09-04' of git://git.kernel.dk/linux-block:
  io_uring: no read/write-retry on -EAGAIN error and O_NONBLOCK marked file
  io_uring: set table->files[i] to NULL when io_sqe_file_register failed
  io_uring: fix removing the wrong file in __io_sqe_files_update()

Merge tag 'thermal-v5.9-rc4' of git://git./linux/kernel/git/thermal/linux

Pull thermal fixes from Daniel Lezcano:

- Fix bogus thermal shutdowns for omap4430 where bogus values resulting
   from an incorrect ADC conversion are too high and fire an emergency
   shutdown (Tony Lindgren)

- Don't suppress negative temp for qcom spmi as they are valid and
   userspace needs them (Veera Vegivada)

- Fix use-after-free in thermal_zone_device_unregister reported by
   Kasan (Dmitry Osipenko)

* tag 'thermal-v5.9-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/thermal/linux:
  thermal: core: Fix use-after-free in thermal_zone_device_unregister()
  thermal: qcom-spmi-temp-alarm: Don't suppress negative temp
  thermal: ti-soc-thermal: Fix bogus thermal shutdowns for omap4430

Merge tag 'dmaengine-fix-5.9-rc4' of git://git./linux/kernel/git/vkoul/dmaengine

Pull dmaengine fixes from Vinod Koul:
"A couple of core fixes and odd driver fixes for dmaengine subsystem:

  Core:
   - drop ACPI CSRT table reference after using it
   - fix of_dma_router_xlate() error handling

  Drivers fixes in idxd, at_hdmac, pl330, dw-edma and jz478"

* tag 'dmaengine-fix-5.9-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/vkoul/dmaengine:
  dmaengine: ti: k3-udma: Update rchan_oes_offset for am654 SYSFW ABI 3.0
  drivers/dma/dma-jz4780: Fix race condition between probe and irq handler
  dmaengine: dw-edma: Fix scatter-gather address calculation
  dmaengine: ti: k3-udma: Fix the TR initialization for prep_slave_sg
  dmaengine: pl330: Fix burst length if burst size is smaller than bus width
  dmaengine: at_hdmac: add missing kfree() call in at_dma_xlate()
  dmaengine: at_hdmac: add missing put_device() call in at_dma_xlate()
  dmaengine: at_hdmac: check return value of of_find_device_by_node() in at_dma_xlate()
  dmaengine: of-dma: Fix of_dma_router_xlate's of_dma_xlate handling
  dmaengine: idxd: reset states after device disable or reset
  dmaengine: acpi: Put the CSRT table after using it

Merge tag 'sound-5.9-rc4' of git://git./linux/kernel/git/tiwai/sound

Pull sound fixes from Takashi Iwai:
"A collection of small changes, nothing intrusive:

   - remaining tasklet API conversions, now all sound stuff have been
     converted

   - a few HD-audio and USB-audio quirks and minor fixes

   - FireWire Tascam and Digi00xx fixes

   - drop a kernel WARNING from PCM OSS for syzkaller"

* tag 'sound-5.9-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound: (29 commits)
  ALSA: hda/realtek - Improved routing for Thinkpad X1 7th/8th Gen
  ALSA: hda: use consistent HDAudio spelling in comments/docs
  ALSA: hda: add dev_dbg log when driver is not selected
  ALSA: hda: fix a runtime pm issue in SOF when integrated GPU is disabled
  ALSA: hda: hdmi - add Rocketlake support
  ALSA: ua101: convert tasklets to use new tasklet_setup() API
  ALSA: usb-audio: convert tasklets to use new tasklet_setup() API
  ASoC: txx9: convert tasklets to use new tasklet_setup() API
  ASoC: siu: convert tasklets to use new tasklet_setup() API
  ASoC: fsl_esai: convert tasklets to use new tasklet_setup() API
  ALSA: hdsp: convert tasklets to use new tasklet_setup() API
  ALSA: riptide: convert tasklets to use new tasklet_setup() API
  ALSA: pci/asihpi: convert tasklets to use new tasklet_setup() API
  ALSA: firewire: convert tasklets to use new tasklet_setup() API
  ALSA: core: convert tasklets to use new tasklet_setup() API
  ALSA: pcm: oss: Remove superfluous WARN_ON() for mulaw sanity check
  ALSA: hda - Fix silent audio output and corrupted input on MSI X570-A PRO
  ALSA: hda/hdmi: always check pin power status in i915 pin fixup
  ALSA: hda/realtek: Add quirk for Samsung Galaxy Book Ion NT950XCJ-X716A
  ALSA: usb-audio: Add basic capture support for Pioneer DJ DJM-250MK2
  ...

Merge tag 'drm-fixes-2020-09-04' of git://anongit.freedesktop.org/drm/drm

Pull drm fixes from Dave Airlie:
"Not much going on this week, nouveau has a display hw bug workaround,
  amdgpu has some PM fixes and CIK regression fixes, one single radeon
  PLL fix, and a couple of i915 display fixes.

  amdgpu:
   - Fix for 32bit systems
   - SW CTF fix
   - Update for Sienna Cichlid
   - CIK bug fixes

  radeon:
   - PLL fix

  i915:
   - Clang build warning fix
   - HDCP fixes

  nouveau:
   - display fixes"

* tag 'drm-fixes-2020-09-04' of git://anongit.freedesktop.org/drm/drm:
  drm/nouveau/kms/nv50-gp1xx: add WAR for EVO push buffer HW bug
  drm/nouveau/kms/nv50-gp1xx: disable notifies again after core update
  drm/nouveau/kms/nv50-: add some whitespace before debug message
  drm/nouveau/kms/gv100-: Include correct push header in crcc37d.c
  drm/radeon: Prefer lower feedback dividers
  drm/amdgpu: Fix bug in reporting voltage for CIK
  drm/amdgpu: Specify get_argument function for ci_smu_funcs
  drm/amd/pm: enable MP0 DPM for sienna_cichlid
  drm/amd/pm: avoid false alarm due to confusing softwareshutdowntemp setting
  drm/amd/pm: fix is_dpm_running() run error on 32bit system
  drm/i915: Clear the repeater bit on HDCP disable
  drm/i915: Fix sha_text population code
  drm/i915/display: Ensure that ret is always initialized in icl_combo_phy_verify_state

net/packet: fix overflow in tpacket_rcv

Using tp_reserve to calculate netoff can overflow as
tp_reserve is unsigned int and netoff is unsigned short.

This may lead to macoff receving a smaller value then
sizeof(struct virtio_net_hdr), and if po->has_vnet_hdr
is set, an out-of-bounds write will occur when
calling virtio_net_hdr_from_skb.

The bug is fixed by converting netoff to unsigned int
and checking if it exceeds USHRT_MAX.

This addresses CVE-2020-14386

Fixes: 8913336a7e8d ("packet: add PACKET_RESERVE sockopt")
Signed-off-by: Or Cohen <orcohen@paloaltonetworks.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Merge branch 'simplify-do_wp_page'

Merge emailed patches from Peter Xu:
"This is a small series that I picked up from Linus's suggestion to
  simplify cow handling (and also make it more strict) by checking
  against page refcounts rather than mapcounts.

  This makes uffd-wp work again (verified by running upmapsort)"

Note: this is horrendously bad timing, and making this kind of
fundamental vm change after -rc3 is not at all how things should work.
The saving grace is that it really is a a nice simplification:

8 files changed, 29 insertions(+), 120 deletions(-)

The reason for the bad timing is that it turns out that commit
17839856fd58 ("gup: document and work around 'COW can break either way'
issue" broke not just UFFD functionality (as Peter noticed), but Mikulas
Patocka also reports that it caused issues for strace when running in a
DAX environment with ext4 on a persistent memory setup.

And we can't just revert that commit without re-introducing the original
issue that is a potential security hole, so making COW stricter (and in
the process much simpler) is a step to then undoing the forced COW that
broke other uses.

Link: https://lore.kernel.org/lkml/alpine.LRH.2.02.2009031328040.6929@file01.intranet.prod.int.rdu2.redhat.com/
* emailed patches from Peter Xu <peterx@redhat.com>:
  mm: Add PGREUSE counter
  mm/gup: Remove enfornced COW mechanism
  mm/ksm: Remove reuse_ksm_page()
  mm: do_wp_page() simplification

Merge branch 'pm-cpufreq'

* pm-cpufreq:
  cpufreq: intel_pstate: Fix intel_pstate_get_hwp_max() for turbo disabled
  cpufreq: intel_pstate: Free memory only when turning off
  cpufreq: intel_pstate: Add ->offline and ->online callbacks
  cpufreq: intel_pstate: Tweak the EPP sysfs interface
  cpufreq: intel_pstate: Update cached EPP in the active mode
  cpufreq: intel_pstate: Refuse to turn off with HWP enabled

mm: Add PGREUSE counter

This accounts for wp_page_reuse() case, where we reused a page for COW.

Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/gup: Remove enfornced COW mechanism

With the more strict (but greatly simplified) page reuse logic in
do_wp_page(), we can safely go back to the world where cow is not
enforced with writes.

This essentially reverts commit 17839856fd58 ("gup: document and work
around 'COW can break either way' issue").  There are some context
differences due to some changes later on around it:

  2170ecfa7688 ("drm/i915: convert get_user_pages() --> pin_user_pages()", 2020-06-03)
  376a34efa4ee ("mm/gup: refactor and de-duplicate gup_fast() code", 2020-06-03)

Some lines moved back and forth with those, but this revert patch should
have striped out and covered all the enforced cow bits anyways.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/ksm: Remove reuse_ksm_page()

Remove the function as the last reference has gone away with the do_wp_page()
changes.

Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: do_wp_page() simplification

How about we just make sure we're the only possible valid user fo the
page before we bother to reuse it?

Simplify, simplify, simplify.

And get rid of the nasty serialization on the page lock at the same time.

[peterx: add subject prefix]

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

gcov: Disable gcov build with GCC 10

GCOV built with GCC 10 doesn't initialize n_function variable. This
produces different kernel panics as was seen by Colin in Ubuntu and me
in FC 32.

As a workaround, let's disable GCOV build for broken GCC 10 version.

Link: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1891288
Link: https://lore.kernel.org/lkml/20200827133932.3338519-1-leon@kernel.org
Link: https://lore.kernel.org/lkml/CAHk-=whbijeSdSvx-Xcr0DPMj0BiwhJ+uiNnDSVZcr_h_kg7UA@mail.gmail.com/
Cc: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

init: fix error check in clean_path()

init_stat() returns 0 on success, same as vfs_lstat(). When it replaced
vfs_lstat(), the '!' was dropped.

Fixes: 716308a5331b ("init: add an init_stat helper")
Signed-off-by: Barret Rhoden <brho@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>