Maxim Levitsky [Tue, 22 Mar 2022 17:24:47 +0000 (19:24 +0200)]
kvm: x86: SVM: remove unused defines
Remove some unused #defines from svm.c
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <
20220322172449.235575-7-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Maxim Levitsky [Tue, 22 Mar 2022 17:24:46 +0000 (19:24 +0200)]
KVM: x86: SVM: move tsc ratio definitions to svm.h
Another piece of SVM spec which should be in the header file
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <
20220322172449.235575-6-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Maxim Levitsky [Tue, 22 Mar 2022 17:24:45 +0000 (19:24 +0200)]
KVM: x86: SVM: fix avic spec based definitions again
Due to wrong rebase, commit
4a204f7895878 ("KVM: SVM: Allow AVIC support on system w/ physical APIC ID > 255")
moved avic spec #defines back to avic.c.
Move them back, and while at it extend AVIC_DOORBELL_PHYSICAL_ID_MASK to 12
bits as well (it will be used in nested avic)
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <
20220322172449.235575-5-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo Bonzini [Sun, 13 Mar 2022 14:05:22 +0000 (15:05 +0100)]
KVM: MIPS: remove reference to trap&emulate virtualization
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <
20220313140522.1307751-1-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo Bonzini [Tue, 15 Mar 2022 22:17:15 +0000 (18:17 -0400)]
KVM: x86: document limitations of MSR filtering
MSR filtering requires an exit to userspace that is hard to implement and
would be very slow in the case of nested VMX vmexit and vmentry MSR
accesses. Document the limitation.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Hou Wenlong [Mon, 7 Mar 2022 12:26:33 +0000 (20:26 +0800)]
KVM: x86: Only do MSR filtering when access MSR by rdmsr/wrmsr
If MSR access is rejected by MSR filtering,
kvm_set_msr()/kvm_get_msr() would return KVM_MSR_RET_FILTERED,
and the return value is only handled well for rdmsr/wrmsr.
However, some instruction emulation and state transition also
use kvm_set_msr()/kvm_get_msr() to do msr access but may trigger
some unexpected results if MSR access is rejected, E.g. RDPID
emulation would inject a #UD but RDPID wouldn't cause a exit
when RDPID is supported in hardware and ENABLE_RDTSCP is set.
And it would also cause failure when load MSR at nested entry/exit.
Since msr filtering is based on MSR bitmap, it is better to only
do MSR filtering for rdmsr/wrmsr.
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Message-Id: <
2b2774154f7532c96a6f04d71c82a8bec7d9e80b.
1646655860.git.houwenlong.hwl@antgroup.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Hou Wenlong [Wed, 2 Mar 2022 13:15:14 +0000 (21:15 +0800)]
KVM: x86/emulator: Emulate RDPID only if it is enabled in guest
When RDTSCP is supported but RDPID is not supported in host,
RDPID emulation is available. However, __kvm_get_msr() would
only fail when RDTSCP/RDPID both are disabled in guest, so
the emulator wouldn't inject a #UD when RDPID is disabled but
RDTSCP is enabled in guest.
Fixes:
fb6d4d340e05 ("KVM: x86: emulate RDPID")
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Message-Id: <
1dfd46ae5b76d3ed87bde3154d51c64ea64c99c1.
1646226788.git.houwenlong.hwl@antgroup.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Like Xu [Wed, 9 Mar 2022 08:42:57 +0000 (16:42 +0800)]
KVM: x86/pmu: Fix and isolate TSX-specific performance event logic
HSW_IN_TX* bits are used in generic code which are not supported on
AMD. Worse, these bits overlap with AMD EventSelect[11:8] and hence
using HSW_IN_TX* bits unconditionally in generic code is resulting in
unintentional pmu behavior on AMD. For example, if EventSelect[11:8]
is 0x2, pmc_reprogram_counter() wrongly assumes that
HSW_IN_TX_CHECKPOINTED is set and thus forces sampling period to be 0.
Also per the SDM, both bits 32 and 33 "may only be set if the processor
supports HLE or RTM" and for "IN_TXCP (bit 33): this bit may only be set
for IA32_PERFEVTSEL2."
Opportunistically eliminate code redundancy, because if the HSW_IN_TX*
bit is set in pmc->eventsel, it is already set in attr.config.
Reported-by: Ravi Bangoria <ravi.bangoria@amd.com>
Reported-by: Jim Mattson <jmattson@google.com>
Fixes:
103af0a98788 ("perf, kvm: Support the in_tx/in_tx_cp modifiers in KVM arch perfmon emulation v5")
Co-developed-by: Ravi Bangoria <ravi.bangoria@amd.com>
Signed-off-by: Ravi Bangoria <ravi.bangoria@amd.com>
Signed-off-by: Like Xu <likexu@tencent.com>
Message-Id: <
20220309084257.88931-1-likexu@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Maxim Levitsky [Wed, 2 Mar 2022 10:24:57 +0000 (12:24 +0200)]
KVM: x86: mmu: trace kvm_mmu_set_spte after the new SPTE was set
It makes more sense to print new SPTE value than the
old value.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <
20220302102457.588450-1-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Jim Mattson [Sat, 26 Feb 2022 23:41:31 +0000 (15:41 -0800)]
KVM: x86/svm: Clear reserved bits written to PerfEvtSeln MSRs
AMD EPYC CPUs never raise a #GP for a WRMSR to a PerfEvtSeln MSR. Some
reserved bits are cleared, and some are not. Specifically, on
Zen3/Milan, bits 19 and 42 are not cleared.
When emulating such a WRMSR, KVM should not synthesize a #GP,
regardless of which bits are set. However, undocumented bits should
not be passed through to the hardware MSR. So, rather than checking
for reserved bits and synthesizing a #GP, just clear the reserved
bits.
This may seem pedantic, but since KVM currently does not support the
"Host/Guest Only" bits (41:40), it is necessary to clear these bits
rather than synthesizing #GP, because some popular guests (e.g Linux)
will set the "Host Only" bit even on CPUs that don't support
EFER.SVME, and they don't expect a #GP.
For example,
root@Ubuntu1804:~# perf stat -e r26 -a sleep 1
Performance counter stats for 'system wide':
0 r26
1.
001070977 seconds time elapsed
Feb 23 03:59:58 Ubuntu1804 kernel: [ 405.379957] unchecked MSR access error: WRMSR to 0xc0010200 (tried to write 0x0000020000130026) at rIP: 0xffffffff9b276a28 (native_write_msr+0x8/0x30)
Feb 23 03:59:58 Ubuntu1804 kernel: [ 405.379958] Call Trace:
Feb 23 03:59:58 Ubuntu1804 kernel: [ 405.379963] amd_pmu_disable_event+0x27/0x90
Fixes:
ca724305a2b0 ("KVM: x86/vPMU: Implement AMD vPMU code for KVM")
Reported-by: Lotus Fenn <lotusf@google.com>
Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Like Xu <likexu@tencent.com>
Reviewed-by: David Dunn <daviddunn@google.com>
Message-Id: <
20220226234131.2167175-1-jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Fri, 11 Mar 2022 04:35:17 +0000 (04:35 +0000)]
KVM: x86: Trace all APICv inhibit changes and capture overall status
Trace all APICv inhibit changes instead of just those that result in
APICv being (un)inhibited, and log the current state. Debugging why
APICv isn't working is frustrating as it's hard to see why APICv is still
inhibited, and logging only the first inhibition means unnecessary onion
peeling.
Opportunistically drop the export of the tracepoint, it is not and should
not be used by vendor code due to the need to serialize toggling via
apicv_update_lock.
Note, using the common flow means kvm_apicv_init() switched from atomic
to non-atomic bitwise operations. The VM is unreachable at init, so
non-atomic is perfectly ok.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <
20220311043517.17027-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Fri, 11 Mar 2022 04:35:16 +0000 (04:35 +0000)]
KVM: x86: Add wrappers for setting/clearing APICv inhibits
Add set/clear wrappers for toggling APICv inhibits to make the call sites
more readable, and opportunistically rename the inner helpers to align
with the new wrappers and to make them more readable as well. Invert the
flag from "activate" to "set"; activate is painfully ambiguous as it's
not obvious if the inhibit is being activated, or if APICv is being
activated, in which case the inhibit is being deactivated.
For the functions that take @set, swap the order of the inhibit reason
and @set so that the call sites are visually similar to those that bounce
through the wrapper.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <
20220311043517.17027-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Fri, 11 Mar 2022 04:35:15 +0000 (04:35 +0000)]
KVM: x86: Make APICv inhibit reasons an enum and cleanup naming
Use an enum for the APICv inhibit reasons, there is no meaning behind
their values and they most definitely are not "unsigned longs". Rename
the various params to "reason" for consistency and clarity (inhibit may
be confused as a command, i.e. inhibit APICv, instead of the reason that
is getting toggled/checked).
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <
20220311043517.17027-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Lai Jiangshan [Fri, 11 Mar 2022 07:03:44 +0000 (15:03 +0800)]
KVM: X86: Handle implicit supervisor access with SMAP
There are two kinds of implicit supervisor access
implicit supervisor access when CPL = 3
implicit supervisor access when CPL < 3
Current permission_fault() handles only the first kind for SMAP.
But if the access is implicit when SMAP is on, data may not be read
nor write from any user-mode address regardless the current CPL.
So the second kind should be also supported.
The first kind can be detect via CPL and access mode: if it is
supervisor access and CPL = 3, it must be implicit supervisor access.
But it is not possible to detect the second kind without extra
information, so this patch adds an artificial PFERR_EXPLICIT_ACCESS
into @access. This extra information also works for the first kind, so
the logic is changed to use this information for both cases.
The value of PFERR_EXPLICIT_ACCESS is deliberately chosen to be bit 48
which is in the most significant 16 bits of u64 and less likely to be
forced to change due to future hardware uses it.
This patch removes the call to ->get_cpl() for access mode is determined
by @access. Not only does it reduce a function call, but also remove
confusions when the permission is checked for nested TDP. The nested
TDP shouldn't have SMAP checking nor even the L2's CPL have any bearing
on it. The original code works just because it is always user walk for
NPT and SMAP fault is not set for EPT in update_permission_bitmask.
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Message-Id: <
20220311070346.45023-5-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Lai Jiangshan [Fri, 11 Mar 2022 07:03:43 +0000 (15:03 +0800)]
KVM: X86: Rename variable smap to not_smap in permission_fault()
Comments above the variable says the bit is set when SMAP is overridden
or the same meaning in update_permission_bitmask(): it is not subjected
to SMAP restriction.
Renaming it to reflect the negative implication and make the code better
readability.
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Message-Id: <
20220311070346.45023-4-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Lai Jiangshan [Fri, 11 Mar 2022 07:03:42 +0000 (15:03 +0800)]
KVM: X86: Fix comments in update_permission_bitmask
The commit
09f037aa48f3 ("KVM: MMU: speedup update_permission_bitmask")
refactored the code of update_permission_bitmask() and change the
comments. It added a condition into a list to match the new code,
so the number/order for conditions in the comments should be updated
too.
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Message-Id: <
20220311070346.45023-3-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Lai Jiangshan [Fri, 11 Mar 2022 07:03:41 +0000 (15:03 +0800)]
KVM: X86: Change the type of access u32 to u64
Change the type of access u32 to u64 for FNAME(walk_addr) and
->gva_to_gpa().
The kinds of accesses are usually combinations of UWX, and VMX/SVM's
nested paging adds a new factor of access: is it an access for a guest
page table or for a final guest physical address.
And SMAP relies a factor for supervisor access: explicit or implicit.
So @access in FNAME(walk_addr) and ->gva_to_gpa() is better to include
all these information to do the walk.
Although @access(u32) has enough bits to encode all the kinds, this
patch extends it to u64:
o Extra bits will be in the higher 32 bits, so that we can
easily obtain the traditional access mode (UWX) by converting
it to u32.
o Reuse the value for the access kind defined by SVM's nested
paging (PFERR_GUEST_FINAL_MASK and PFERR_GUEST_PAGE_MASK) as
@error_code in kvm_handle_page_fault().
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Message-Id: <
20220311070346.45023-2-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
David Woodhouse [Thu, 3 Mar 2022 15:41:12 +0000 (15:41 +0000)]
KVM: Remove dirty handling from gfn_to_pfn_cache completely
It isn't OK to cache the dirty status of a page in internal structures
for an indefinite period of time.
Any time a vCPU exits the run loop to userspace might be its last; the
VMM might do its final check of the dirty log, flush the last remaining
dirty pages to the destination and complete a live migration. If we
have internal 'dirty' state which doesn't get flushed until the vCPU
is finally destroyed on the source after migration is complete, then
we have lost data because that will escape the final copy.
This problem already exists with the use of kvm_vcpu_unmap() to mark
pages dirty in e.g. VMX nesting.
Note that the actual Linux MM already considers the page to be dirty
since we have a writeable mapping of it. This is just about the KVM
dirty logging.
For the nesting-style use cases (KVM_GUEST_USES_PFN) we will need to
track which gfn_to_pfn_caches have been used and explicitly mark the
corresponding pages dirty before returning to userspace. But we would
have needed external tracking of that anyway, rather than walking the
full list of GPCs to find those belonging to this vCPU which are dirty.
So let's rely *solely* on that external tracking, and keep it simple
rather than laying a tempting trap for callers to fall into.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <
20220303154127.202856-3-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Thu, 3 Mar 2022 15:41:11 +0000 (15:41 +0000)]
KVM: Use enum to track if cached PFN will be used in guest and/or host
Replace the guest_uses_pa and kernel_map booleans in the PFN cache code
with a unified enum/bitmask. Using explicit names makes it easier to
review and audit call sites.
Opportunistically add a WARN to prevent passing garbage; instantating a
cache without declaring its usage is either buggy or pointless.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <
20220303154127.202856-2-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Peter Gonda [Fri, 4 Mar 2022 16:10:32 +0000 (08:10 -0800)]
KVM: SVM: Fix kvm_cache_regs.h inclusions for is_guest_mode()
Include kvm_cache_regs.h to pick up the definition of is_guest_mode(),
which is referenced by nested_svm_virtualize_tpr() in svm.h. Remove
include from svm_onhpyerv.c which was done only because of lack of
include in svm.h.
Fixes:
883b0a91f41ab ("KVM: SVM: Move Nested SVM Implementation to nested.c")
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Peter Gonda <pgonda@google.com>
Message-Id: <
20220304161032.2270688-1-pgonda@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Jim Mattson [Tue, 8 Mar 2022 01:24:52 +0000 (17:24 -0800)]
KVM: x86/pmu: Use different raw event masks for AMD and Intel
The third nybble of AMD's event select overlaps with Intel's IN_TX and
IN_TXCP bits. Therefore, we can't use AMD64_RAW_EVENT_MASK on Intel
platforms that support TSX.
Declare a raw_event_mask in the kvm_pmu structure, initialize it in
the vendor-specific pmu_refresh() functions, and use that mask for
PERF_TYPE_RAW configurations in reprogram_gp_counter().
Fixes:
710c47651431 ("KVM: x86/pmu: Use AMD64_RAW_EVENT_MASK for PERF_TYPE_RAW")
Signed-off-by: Jim Mattson <jmattson@google.com>
Message-Id: <
20220308012452.3468611-1-jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Wed, 23 Feb 2022 16:53:02 +0000 (16:53 +0000)]
KVM: Don't actually set a request when evicting vCPUs for GFN cache invd
Don't actually set a request bit in vcpu->requests when making a request
purely to force a vCPU to exit the guest. Logging a request but not
actually consuming it would cause the vCPU to get stuck in an infinite
loop during KVM_RUN because KVM would see the pending request and bail
from VM-Enter to service the request.
Note, it's currently impossible for KVM to set KVM_REQ_GPC_INVALIDATE as
nothing in KVM is wired up to set guest_uses_pa=true. But, it'd be all
too easy for arch code to introduce use of kvm_gfn_to_pfn_cache_init()
without implementing handling of the request, especially since getting
test coverage of MMU notifier interaction with specific KVM features
usually requires a directed test.
Opportunistically rename gfn_to_pfn_cache_invalidate_start()'s wake_vcpus
to evict_vcpus. The purpose of the request is to get vCPUs out of guest
mode, it's supposed to _avoid_ waking vCPUs that are blocking.
Opportunistically rename KVM_REQ_GPC_INVALIDATE to be more specific as to
what it wants to accomplish, and to genericize the name so that it can
used for similar but unrelated scenarios, should they arise in the future.
Add a comment and documentation to explain why the "no action" request
exists.
Add compile-time assertions to help detect improper usage. Use the inner
assertless helper in the one s390 path that makes requests without a
hardcoded request.
Cc: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <
20220223165302.3205276-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
David Woodhouse [Tue, 29 Mar 2022 17:11:47 +0000 (13:11 -0400)]
KVM: avoid double put_page with gfn-to-pfn cache
If the cache's user host virtual address becomes invalid, there
is still a path from kvm_gfn_to_pfn_cache_refresh() where __release_gpc()
could release the pfn but the gpc->pfn field has not been overwritten
with an error value. If this happens, kvm_gfn_to_pfn_cache_unmap will
call put_page again on the same page.
Cc: stable@vger.kernel.org
Fixes:
982ed0de4753 ("KVM: Reinstate gfn_to_pfn_cache with invalidation support")
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Fri, 25 Mar 2022 23:03:48 +0000 (23:03 +0000)]
KVM: x86/mmu: Zap only TDP MMU leafs in zap range and mmu_notifier unmap
Re-introduce zapping only leaf SPTEs in kvm_zap_gfn_range() and
kvm_tdp_mmu_unmap_gfn_range(), this time without losing a pending TLB
flush when processing multiple roots (including nested TDP shadow roots).
Dropping the TLB flush resulted in random crashes when running Hyper-V
Server 2019 in a guest with KSM enabled in the host (or any source of
mmu_notifier invalidations, KSM is just the easiest to force).
This effectively revert commits
873dd122172f8cce329113cfb0dfe3d2344d80c0
and
fcb93eb6d09dd302cbef22bd95a5858af75e4156, and thus restores commit
cf3e26427c08ad9015956293ab389004ac6a338e, plus this delta on top:
bool kvm_tdp_mmu_zap_leafs(struct kvm *kvm, int as_id, gfn_t start, gfn_t end,
struct kvm_mmu_page *root;
for_each_tdp_mmu_root_yield_safe(kvm, root, as_id)
- flush = tdp_mmu_zap_leafs(kvm, root, start, end, can_yield, false);
+ flush = tdp_mmu_zap_leafs(kvm, root, start, end, can_yield, flush);
return flush;
}
Cc: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <
20220325230348.2587437-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Yi Wang [Wed, 9 Mar 2022 11:30:25 +0000 (19:30 +0800)]
KVM: SVM: fix panic on out-of-bounds guest IRQ
As guest_irq is coming from KVM_IRQFD API call, it may trigger
crash in svm_update_pi_irte() due to out-of-bounds:
crash> bt
PID: 22218 TASK:
ffff951a6ad74980 CPU: 73 COMMAND: "vcpu8"
#0 [
ffffb1ba6707fa40] machine_kexec at
ffffffff8565b397
#1 [
ffffb1ba6707fa90] __crash_kexec at
ffffffff85788a6d
#2 [
ffffb1ba6707fb58] crash_kexec at
ffffffff8578995d
#3 [
ffffb1ba6707fb70] oops_end at
ffffffff85623c0d
#4 [
ffffb1ba6707fb90] no_context at
ffffffff856692c9
#5 [
ffffb1ba6707fbf8] exc_page_fault at
ffffffff85f95b51
#6 [
ffffb1ba6707fc50] asm_exc_page_fault at
ffffffff86000ace
[exception RIP: svm_update_pi_irte+227]
RIP:
ffffffffc0761b53 RSP:
ffffb1ba6707fd08 RFLAGS:
00010086
RAX:
ffffb1ba6707fd78 RBX:
ffffb1ba66d91000 RCX:
0000000000000001
RDX:
00003c803f63f1c0 RSI:
000000000000019a RDI:
ffffb1ba66db2ab8
RBP:
000000000000019a R8:
0000000000000040 R9:
ffff94ca41b82200
R10:
ffffffffffffffcf R11:
0000000000000001 R12:
0000000000000001
R13:
0000000000000001 R14:
ffffffffffffffcf R15:
000000000000005f
ORIG_RAX:
ffffffffffffffff CS: 0010 SS: 0018
#7 [
ffffb1ba6707fdb8] kvm_irq_routing_update at
ffffffffc09f19a1 [kvm]
#8 [
ffffb1ba6707fde0] kvm_set_irq_routing at
ffffffffc09f2133 [kvm]
#9 [
ffffb1ba6707fe18] kvm_vm_ioctl at
ffffffffc09ef544 [kvm]
RIP:
00007f143c36488b RSP:
00007f143a4e04b8 RFLAGS:
00000246
RAX:
ffffffffffffffda RBX:
00007f05780041d0 RCX:
00007f143c36488b
RDX:
00007f05780041d0 RSI:
000000004008ae6a RDI:
0000000000000020
RBP:
00000000000004e8 R8:
0000000000000008 R9:
00007f05780041e0
R10:
00007f0578004560 R11:
0000000000000246 R12:
00000000000004e0
R13:
000000000000001a R14:
00007f1424001c60 R15:
00007f0578003bc0
ORIG_RAX:
0000000000000010 CS: 0033 SS: 002b
Vmx have been fix this in commit
3a8b0677fc61 (KVM: VMX: Do not BUG() on
out-of-bounds guest IRQ), so we can just copy source from that to fix
this.
Co-developed-by: Yi Liu <liu.yi24@zte.com.cn>
Signed-off-by: Yi Liu <liu.yi24@zte.com.cn>
Signed-off-by: Yi Wang <wang.yi59@zte.com.cn>
Message-Id: <
20220309113025.44469-1-wang.yi59@zte.com.cn>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo Bonzini [Fri, 25 Mar 2022 16:42:52 +0000 (12:42 -0400)]
KVM: MMU: propagate alloc_workqueue failure
If kvm->arch.tdp_mmu_zap_wq cannot be created, the failure has
to be propagated up to kvm_mmu_init_vm and kvm_arch_init_vm.
kvm_arch_init_vm also has to undo all the initialization, so
group all the MMU initialization code at the beginning and
handle cleaning up of kvm_page_track_init.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Vitaly Kuznetsov [Fri, 25 Mar 2022 13:21:40 +0000 (14:21 +0100)]
KVM: x86: Forbid VMM to set SYNIC/STIMER MSRs when SynIC wasn't activated
Setting non-zero values to SYNIC/STIMER MSRs activates certain features,
this should not happen when KVM_CAP_HYPERV_SYNIC{,2} was not activated.
Note, it would've been better to forbid writing anything to SYNIC/STIMER
MSRs, including zeroes, however, at least QEMU tries clearing
HV_X64_MSR_STIMER0_CONFIG without SynIC. HV_X64_MSR_EOM MSR is somewhat
'special' as writing zero there triggers an action, this also should not
happen when SynIC wasn't activated.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <
20220325132140.25650-4-vkuznets@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Vitaly Kuznetsov [Fri, 25 Mar 2022 13:21:39 +0000 (14:21 +0100)]
KVM: x86: Avoid theoretical NULL pointer dereference in kvm_irq_delivery_to_apic_fast()
When kvm_irq_delivery_to_apic_fast() is called with APIC_DEST_SELF
shorthand, 'src' must not be NULL. Crash the VM with KVM_BUG_ON()
instead of crashing the host.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <
20220325132140.25650-3-vkuznets@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Vitaly Kuznetsov [Fri, 25 Mar 2022 13:21:38 +0000 (14:21 +0100)]
KVM: x86: Check lapic_in_kernel() before attempting to set a SynIC irq
When KVM_CAP_HYPERV_SYNIC{,2} is activated, KVM already checks for
irqchip_in_kernel() so normally SynIC irqs should never be set. It is,
however, possible for a misbehaving VMM to write to SYNIC/STIMER MSRs
causing erroneous behavior.
The immediate issue being fixed is that kvm_irq_delivery_to_apic()
(kvm_irq_delivery_to_apic_fast()) crashes when called with
'irq.shorthand = APIC_DEST_SELF' and 'src == NULL'.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <
20220325132140.25650-2-vkuznets@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo Bonzini [Tue, 22 Mar 2022 11:07:12 +0000 (12:07 +0100)]
Documentation: KVM: add API issues section
Add a section to document all the different ways in which the KVM API sucks.
I am sure there are way more, give people a place to vent so that userspace
authors are aware.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <
20220322110712.222449-4-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo Bonzini [Tue, 22 Mar 2022 11:07:11 +0000 (12:07 +0100)]
Documentation: KVM: add virtual CPU errata documentation
Add a file to document all the different ways in which the virtual CPU
emulation is imperfect. Include an example to show how to document
such errata.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Oliver Upton <oupton@google.com>
Message-Id: <
20220322110712.222449-3-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo Bonzini [Tue, 22 Mar 2022 11:07:10 +0000 (12:07 +0100)]
Documentation: KVM: add separate directories for architecture-specific documentation
ARM already has an arm/ subdirectory, but s390 and x86 do not even though
they have a relatively large number of files specific to them. Create
new directories in Documentation/virt/kvm for these two architectures
as well.
While at it, group the API documentation and the developer documentation
in the table of contents.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <
20220322110712.222449-2-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo Bonzini [Tue, 22 Mar 2022 11:07:20 +0000 (12:07 +0100)]
Documentation: kvm: include new locks
kvm->mn_invalidate_lock and kvm->slots_arch_lock were not included in the
documentation, add them.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <
20220322110720.222499-3-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo Bonzini [Tue, 22 Mar 2022 11:07:19 +0000 (12:07 +0100)]
Documentation: kvm: fixes for locking.rst
Separate the various locks clearly, and include the new names of blocked_vcpu_on_cpu_lock
and blocked_vcpu_on_cpu.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <
20220322110720.222499-2-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Nathan Chancellor [Tue, 22 Mar 2022 15:29:06 +0000 (08:29 -0700)]
KVM: x86: Fix clang -Wimplicit-fallthrough in do_host_cpuid()
Clang warns:
arch/x86/kvm/cpuid.c:739:2: error: unannotated fall-through between switch labels [-Werror,-Wimplicit-fallthrough]
default:
^
arch/x86/kvm/cpuid.c:739:2: note: insert 'break;' to avoid fall-through
default:
^
break;
1 error generated.
Clang is a little more pedantic than GCC, which does not warn when
falling through to a case that is just break or return. Clang's version
is more in line with the kernel's own stance in deprecated.rst, which
states that all switch/case blocks must end in either break,
fallthrough, continue, goto, or return. Add the missing break to silence
the warning.
Fixes:
f144c49e8c39 ("KVM: x86: synthesize CPUID leaf 0x80000021h if useful")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Message-Id: <
20220322152906.112164-1-nathan@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
David Matlack [Thu, 3 Mar 2022 18:33:28 +0000 (18:33 +0000)]
Revert "KVM: set owner of cpu and vm file operations"
This reverts commit
3d3aab1b973b01bd2a1aa46307e94a1380b1d802.
Now that the KVM module's lifetime is tied to kvm.users_count, there is
no need to also tie it's lifetime to the lifetime of the VM and vCPU
file descriptors.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <
20220303183328.1499189-3-dmatlack@google.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
David Matlack [Thu, 3 Mar 2022 18:33:27 +0000 (18:33 +0000)]
KVM: Prevent module exit until all VMs are freed
Tie the lifetime the KVM module to the lifetime of each VM via
kvm.users_count. This way anything that grabs a reference to the VM via
kvm_get_kvm() cannot accidentally outlive the KVM module.
Prior to this commit, the lifetime of the KVM module was tied to the
lifetime of /dev/kvm file descriptors, VM file descriptors, and vCPU
file descriptors by their respective file_operations "owner" field.
This approach is insufficient because references grabbed via
kvm_get_kvm() do not prevent closing any of the aforementioned file
descriptors.
This fixes a long standing theoretical bug in KVM that at least affects
async page faults. kvm_setup_async_pf() grabs a reference via
kvm_get_kvm(), and drops it in an asynchronous work callback. Nothing
prevents the VM file descriptor from being closed and the KVM module
from being unloaded before this callback runs.
Fixes:
af585b921e5d ("KVM: Halt vcpu if page it tries to access is swapped out")
Fixes:
3d3aab1b973b ("KVM: set owner of cpu and vm file operations")
Cc: stable@vger.kernel.org
Suggested-by: Ben Gardon <bgardon@google.com>
[ Based on a patch from Ben implemented for Google's kernel. ]
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <
20220303183328.1499189-2-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo Bonzini [Tue, 8 Mar 2022 09:57:39 +0000 (04:57 -0500)]
KVM: use kvcalloc for array allocations
Instead of using array_size, use a function that takes care of the
multiplication. While at it, switch to kvcalloc since this allocation
should not be very large.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Oliver Upton [Tue, 1 Mar 2022 06:03:47 +0000 (06:03 +0000)]
KVM: x86: Introduce KVM_CAP_DISABLE_QUIRKS2
KVM_CAP_DISABLE_QUIRKS is irrevocably broken. The capability does not
advertise the set of quirks which may be disabled to userspace, so it is
impossible to predict the behavior of KVM. Worse yet,
KVM_CAP_DISABLE_QUIRKS will tolerate any value for cap->args[0], meaning
it fails to reject attempts to set invalid quirk bits.
The only valid workaround for the quirky quirks API is to add a new CAP.
Actually advertise the set of quirks that can be disabled to userspace
so it can predict KVM's behavior. Reject values for cap->args[0] that
contain invalid bits.
Finally, add documentation for the new capability and describe the
existing quirks.
Signed-off-by: Oliver Upton <oupton@google.com>
Message-Id: <
20220301060351.442881-5-oupton@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Thomas Gleixner [Sun, 6 Nov 2011 11:26:18 +0000 (12:26 +0100)]
kvm: x86: Require const tsc for RT
Non constant TSC is a nightmare on bare metal already, but with
virtualization it becomes a complete disaster because the workarounds
are horrible latency wise. That's also a preliminary for running RT in
a guest on top of a RT host.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Message-Id: <Yh5eJSG19S2sjZfy@linutronix.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo Bonzini [Thu, 21 Oct 2021 21:19:27 +0000 (17:19 -0400)]
KVM: x86: synthesize CPUID leaf 0x80000021h if useful
Guests X86_BUG_NULL_SEG if and only if the host has them. Use the info
from static_cpu_has_bug to form the 0x80000021 CPUID leaf that was
defined for Zen3. Userspace can then set the bit even on older CPUs
that do not have the bug, such as Zen2.
Do the same for X86_FEATURE_LFENCE_RDTSC as well, since various processors
have had very different ways of detecting it and not all of them are
available to userspace.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo Bonzini [Thu, 28 Oct 2021 17:26:38 +0000 (13:26 -0400)]
KVM: x86: add support for CPUID leaf 0x80000021
CPUID leaf 0x80000021 defines some features (or lack of bugs) of AMD
processors. Expose the ones that make sense via KVM_GET_SUPPORTED_CPUID.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Maxim Levitsky [Fri, 18 Mar 2022 16:27:41 +0000 (12:27 -0400)]
KVM: x86: do not use KVM_X86_OP_OPTIONAL_RET0 for get_mt_mask
KVM_X86_OP_OPTIONAL_RET0 can only be used with 32-bit return values on 32-bit
systems, because unsigned long is only 32-bits wide there and 64-bit values
are returned in edx:eax.
Reported-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo Bonzini [Fri, 18 Mar 2022 16:30:32 +0000 (12:30 -0400)]
Revert "KVM: x86/mmu: Zap only TDP MMU leafs in kvm_zap_gfn_range()"
This reverts commit
cf3e26427c08ad9015956293ab389004ac6a338e.
Multi-vCPU Hyper-V guests started crashing randomly on boot with the
latest kvm/queue and the problem can be bisected the problem to this
particular patch. Basically, I'm not able to boot e.g. 16-vCPU guest
successfully anymore. Both Intel and AMD seem to be affected. Reverting
the commit saves the day.
Reported-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo Bonzini [Mon, 21 Mar 2022 09:05:08 +0000 (05:05 -0400)]
kvm: x86/mmu: Flush TLB before zap_gfn_range releases RCU
Since "KVM: x86/mmu: Zap only TDP MMU leafs in kvm_zap_gfn_range()"
is going to be reverted, it's not going to be true anymore that
the zap-page flow does not free any 'struct kvm_mmu_page'. Introduce
an early flush before tdp_mmu_zap_leafs() returns, to preserve
bisectability.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo Bonzini [Fri, 18 Mar 2022 16:43:24 +0000 (12:43 -0400)]
Merge tag 'kvmarm-5.18' of git://git./linux/kernel/git/kvmarm/kvmarm into HEAD
KVM/arm64 updates for 5.18
- Proper emulation of the OSLock feature of the debug architecture
- Scalibility improvements for the MMU lock when dirty logging is on
- New VMID allocator, which will eventually help with SVA in VMs
- Better support for PMUs in heterogenous systems
- PSCI 1.1 support, enabling support for SYSTEM_RESET2
- Implement CONFIG_DEBUG_LIST at EL2
- Make CONFIG_ARM64_ERRATUM_2077057 default y
- Reduce the overhead of VM exit when no interrupt is pending
- Remove traces of 32bit ARM host support from the documentation
- Updated vgic selftests
- Various cleanups, doc updates and spelling fixes
Julia Lawall [Fri, 18 Mar 2022 10:37:19 +0000 (11:37 +0100)]
KVM: arm64: fix typos in comments
Various spelling mistakes in comments.
Detected with the help of Coccinelle.
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220318103729.157574-24-Julia.Lawall@inria.fr
Marc Zyngier [Fri, 11 Mar 2022 17:39:47 +0000 (17:39 +0000)]
KVM: arm64: Generalise VM features into a set of flags
We currently deal with a set of booleans for VM features,
while they could be better represented as set of flags
contained in an unsigned long, similarily to what we are
doing on the CPU side.
Signed-off-by: Marc Zyngier <maz@kernel.org>
[Oliver: Flag-ify the 'ran_once' boolean]
Signed-off-by: Oliver Upton <oupton@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220311174001.605719-2-oupton@google.com
Paolo Bonzini [Tue, 15 Mar 2022 21:20:25 +0000 (17:20 -0400)]
Merge tag 'kvm-riscv-5.18-1' of https://github.com/kvm-riscv/linux into HEAD
KVM/riscv changes for 5.18
- Prevent KVM_COMPAT from being selected
- Refine __kvm_riscv_switch_to() implementation
- RISC-V SBI v0.3 support
Paolo Bonzini [Tue, 15 Mar 2022 21:19:02 +0000 (17:19 -0400)]
Merge tag 'kvm-s390-next-5.18-2' of https://git./linux/kernel/git/kvms390/linux into HEAD
KVM: s390: Fix, test and feature for 5.18 part 2
- memop selftest
- fix SCK locking
- adapter interruptions virtualization for secure guests
Janis Schoetterl-Glausch [Tue, 8 Mar 2022 12:58:41 +0000 (13:58 +0100)]
KVM: s390: selftests: Add error memop tests
Test that errors occur if key protection disallows access, including
tests for storage and fetch protection override. Perform tests for both
logical vcpu and absolute vm ioctls.
Also extend the existing tests to the vm ioctl.
Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
Link: https://lore.kernel.org/r/20220308125841.3271721-6-scgl@linux.ibm.com
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Janis Schoetterl-Glausch [Tue, 8 Mar 2022 12:58:40 +0000 (13:58 +0100)]
KVM: s390: selftests: Add more copy memop tests
Do not just test the actual copy, but also that success is indicated
when using the check only flag.
Add copy test with storage key checking enabled, including tests for
storage and fetch protection override.
These test cover both logical vcpu ioctls as well as absolute vm ioctls.
Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
Link: https://lore.kernel.org/r/20220308125841.3271721-5-scgl@linux.ibm.com
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Janis Schoetterl-Glausch [Tue, 8 Mar 2022 12:58:39 +0000 (13:58 +0100)]
KVM: s390: selftests: Add named stages for memop test
The stages synchronize guest and host execution.
This helps the reader and constraits the execution of the test -- if the
observed staging differs from the expected the test fails.
Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
Link: https://lore.kernel.org/r/20220308125841.3271721-4-scgl@linux.ibm.com
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Janis Schoetterl-Glausch [Tue, 8 Mar 2022 12:58:38 +0000 (13:58 +0100)]
KVM: s390: selftests: Add macro as abstraction for MEM_OP
In order to achieve good test coverage we need to be able to invoke the
MEM_OP ioctl with all possible parametrizations.
However, for a given test, we want to be concise and not specify a long
list of default values for parameters not relevant for the test, so the
readers attention is not needlessly diverted.
Add a macro that enables this and convert the existing test to use it.
The macro emulates named arguments and hides some of the ioctl's
redundancy, e.g. sets the key flag if an access key is specified.
Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
Link: https://lore.kernel.org/r/20220308125841.3271721-3-scgl@linux.ibm.com
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Janis Schoetterl-Glausch [Tue, 8 Mar 2022 12:58:37 +0000 (13:58 +0100)]
KVM: s390: selftests: Split memop tests
Split success case/copy test from error test, making them independent.
This means they do not share state and are easier to understand.
Also, new test can be added in the same manner without affecting the old
ones. In order to make that simpler, introduce functionality for the
setup of commonly used variables.
Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
Link: https://lore.kernel.org/r/20220308125841.3271721-2-scgl@linux.ibm.com
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Claudio Imbrenda [Tue, 1 Mar 2022 14:33:40 +0000 (15:33 +0100)]
KVM: s390x: fix SCK locking
When handling the SCK instruction, the kvm lock is taken, even though
the vcpu lock is already being held. The normal locking order is kvm
lock first and then vcpu lock. This is can (and in some circumstances
does) lead to deadlocks.
The function kvm_s390_set_tod_clock is called both by the SCK handler
and by some IOCTLs to set the clock. The IOCTLs will not hold the vcpu
lock, so they can safely take the kvm lock. The SCK handler holds the
vcpu lock, but will also somehow need to acquire the kvm lock without
relinquishing the vcpu lock.
The solution is to factor out the code to set the clock, and provide
two wrappers. One is called like the original function and does the
locking, the other is called kvm_s390_try_set_tod_clock and uses
trylock to try to acquire the kvm lock. This new wrapper is then used
in the SCK handler. If locking fails, -EAGAIN is returned, which is
eventually propagated to userspace, thus also freeing the vcpu lock and
allowing for forward progress.
This is not the most efficient or elegant way to solve this issue, but
the SCK instruction is deprecated and its performance is not critical.
The goal of this patch is just to provide a simple but correct way to
fix the bug.
Fixes:
6a3f95a6b04c ("KVM: s390: Intercept SCK instruction")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Reviewed-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
Link: https://lore.kernel.org/r/20220301143340.111129-1-imbrenda@linux.ibm.com
Cc: stable@vger.kernel.org
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Anup Patel [Mon, 31 Jan 2022 07:01:36 +0000 (12:31 +0530)]
RISC-V: KVM: Implement SBI HSM suspend call
The SBI v0.3 specification extends SBI HSM extension by adding SBI HSM
suspend call and related HART states. This patch extends the KVM RISC-V
HSM implementation to provide KVM guest a minimal SBI HSM suspend call
which is equivalent to a WFI instruction.
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
Anup Patel [Mon, 31 Jan 2022 06:29:44 +0000 (11:59 +0530)]
RISC-V: KVM: Add common kvm_riscv_vcpu_wfi() function
The wait for interrupt (WFI) instruction emulation can share the VCPU
halt logic with SBI HSM suspend emulation so this patch adds a common
kvm_riscv_vcpu_wfi() function for this purpose.
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
Anup Patel [Mon, 15 Feb 2021 05:13:39 +0000 (10:43 +0530)]
RISC-V: Add SBI HSM suspend related defines
We add defines related to SBI HSM suspend call and also update HSM states
naming as-per the latest SBI specification.
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
Anup Patel [Mon, 31 Jan 2022 05:23:13 +0000 (10:53 +0530)]
RISC-V: KVM: Implement SBI v0.3 SRST extension
The SBI v0.3 specification defines SRST (System Reset) extension which
provides a standard poweroff and reboot interface. This patch implements
SRST extension for the KVM Guest.
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
Anup Patel [Mon, 31 Jan 2022 04:59:31 +0000 (10:29 +0530)]
RISC-V: KVM: Add common kvm_riscv_vcpu_sbi_system_reset() function
We rename kvm_sbi_system_shutdown() to kvm_riscv_vcpu_sbi_system_reset()
and move it to vcpu_sbi.c so that it can be shared by SBI v0.1 shutdown
and SBI v0.3 SRST extension.
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
Anup Patel [Mon, 31 Jan 2022 04:41:43 +0000 (10:11 +0530)]
RISC-V: KVM: Upgrade SBI spec version to v0.3
We upgrade SBI spec version implemented by KVM RISC-V to v0.3 so
that Guest kernel can probe and use SBI extensions added by the
SBI v0.3 specification.
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
Vincent Chen [Wed, 23 Feb 2022 01:13:31 +0000 (09:13 +0800)]
RISC-V: KVM: Refine __kvm_riscv_switch_to() implementation
Kernel uses __kvm_riscv_switch_to() and __kvm_switch_return() to switch
the context of host kernel and guest kernel. Several CSRs belonging to the
context will be read and written during the context switch. To ensure
atomic read-modify-write control of CSR and ordering of CSR accesses, some
hardware blocks flush the pipeline when writing a CSR. In this
circumstance, grouping CSR executions together as much as possible can
reduce the performance impact of the pipeline. Therefore, this commit
reorders the CSR instructions to enhance the context switch performance..
Signed-off-by: Vincent Chen <vincent.chen@sifive.com>
Suggested-by: Hsinyi Lee <hsinyi.lee@sifive.com>
Suggested-by: Fu-Ching Yang <fu-ching.yang@sifive.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
Guo Ren [Tue, 1 Feb 2022 15:05:45 +0000 (23:05 +0800)]
KVM: compat: riscv: Prevent KVM_COMPAT from being selected
Current riscv doesn't support the 32bit KVM API. Let's make it
clear by not selecting KVM_COMPAT.
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Anup Patel <anup@brainfault.org>
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Anup Patel <anup@brainfault.org>
Yang Li [Tue, 11 Jan 2022 01:04:54 +0000 (09:04 +0800)]
RISC-V: KVM: remove unneeded semicolon
Eliminate the following coccicheck warning:
./arch/riscv/kvm/vcpu_sbi_v01.c:117:2-3: Unneeded semicolon
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
Marc Zyngier [Wed, 9 Mar 2022 18:19:10 +0000 (18:19 +0000)]
Merge branch kvm-arm64/psci-1.1 into kvmarm-master/next
* kvm-arm64/psci-1.1:
: .
: Limited PSCI-1.1 support from Will Deacon:
:
: This small series exposes the PSCI SYSTEM_RESET2 call to guests, which
: allows the propagation of a "reset_type" and a "cookie" back to the VMM.
: Although Linux guests only ever pass 0 for the type ("SYSTEM_WARM_RESET"),
: the vendor-defined range can be used by a bootloader to provide additional
: information about the reset, such as an error code.
: .
KVM: arm64: Really propagate PSCI SYSTEM_RESET2 arguments to userspace
Signed-off-by: Marc Zyngier <maz@kernel.org>
Will Deacon [Wed, 9 Mar 2022 18:13:08 +0000 (18:13 +0000)]
KVM: arm64: Really propagate PSCI SYSTEM_RESET2 arguments to userspace
Commit
d43583b890e7 ("KVM: arm64: Expose PSCI SYSTEM_RESET2 call to the
guest") hooked up the SYSTEM_RESET2 PSCI call for guests but failed to
preserve its arguments for userspace, instead overwriting them with
zeroes via smccc_set_retval(). As Linux only passes zeroes for these
arguments, this appeared to be working for Linux guests. Oh well.
Don't call smccc_set_retval() for a SYSTEM_RESET2 heading to userspace
and instead set X0 (and only X0) explicitly to PSCI_RET_INTERNAL_FAILURE
just in case the vCPU re-enters the guest.
Fixes:
d43583b890e7 ("KVM: arm64: Expose PSCI SYSTEM_RESET2 call to the guest")
Reported-by: Andrew Walbran <qwandor@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220309181308.982-1-will@kernel.org
Marc Zyngier [Wed, 9 Mar 2022 11:16:48 +0000 (11:16 +0000)]
Merge branch kvm-arm64/misc-5.18 into kvmarm-master/next
* kvm-arm64/misc-5.18:
: .
: Misc fixes for KVM/arm64 5.18:
:
: - Drop unused kvm parameter to kvm_psci_version()
:
: - Implement CONFIG_DEBUG_LIST at EL2
:
: - Make CONFIG_ARM64_ERRATUM_2077057 default y
:
: - Only do the interrupt dance if we have exited because of an interrupt
:
: - Remove traces of 32bit ARM host support from the documentation
: .
Documentation: KVM: Update documentation to indicate KVM is arm64-only
KVM: arm64: Only open the interrupt window on exit due to an interrupt
KVM: arm64: Enable Cortex-A510 erratum 2077057 by default
Signed-off-by: Marc Zyngier <maz@kernel.org>
Oliver Upton [Tue, 8 Mar 2022 17:28:57 +0000 (17:28 +0000)]
Documentation: KVM: Update documentation to indicate KVM is arm64-only
KVM support for 32-bit ARM hosts (KVM/arm) has been removed from the
kernel since commit
541ad0150ca4 ("arm: Remove 32bit KVM host
support"). There still exists some remnants of the old architecture in
the KVM documentation.
Remove all traces of 32-bit host support from the documentation. Note
that AArch32 guests are still supported.
Suggested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Oliver Upton <oupton@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220308172856.2997250-1-oupton@google.com
Suravee Suthikulpanit [Fri, 11 Feb 2022 00:08:51 +0000 (18:08 -0600)]
KVM: SVM: Allow AVIC support on system w/ physical APIC ID > 255
Expand KVM's mask for the AVIC host physical ID to the full 12 bits defined
by the architecture. The number of bits consumed by hardware is model
specific, e.g. early CPUs ignored bits 11:8, but there is no way for KVM
to enumerate the "true" size. So, KVM must allow using all bits, else it
risks rejecting completely legal x2APIC IDs on newer CPUs.
This means KVM relies on hardware to not assign x2APIC IDs that exceed the
"true" width of the field, but presumably hardware is smart enough to tie
the width to the max x2APIC ID. KVM also relies on hardware to support at
least 8 bits, as the legacy xAPIC ID is writable by software. But, those
assumptions are unavoidable due to the lack of any way to enumerate the
"true" width.
Cc: stable@vger.kernel.org
Cc: Maxim Levitsky <mlevitsk@redhat.com>
Suggested-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Fixes:
44a95dae1d22 ("KVM: x86: Detect and Initialize AVIC support")
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Message-Id: <
20220211000851.185799-1-suravee.suthikulpanit@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:46 +0000 (00:15 +0000)]
KVM: selftests: Add test to populate a VM with the max possible guest mem
Add a selftest that enables populating a VM with the maximum amount of
guest memory allowed by the underlying architecture. Abuse KVM's
memslots by mapping a single host memory region into multiple memslots so
that the selftest doesn't require a system with terabytes of RAM.
Default to 512gb of guest memory, which isn't all that interesting, but
should work on all MMUs and doesn't take an exorbitant amount of memory
or time. E.g. testing with ~64tb of guest memory takes the better part
of an hour, and requires 200gb of memory for KVM's page tables when using
4kb pages.
To inflicit maximum abuse on KVM' MMU, default to 4kb pages (or whatever
the not-hugepage size is) in the backing store (memfd). Use memfd for
the host backing store to ensure that hugepages are guaranteed when
requested, and to give the user explicit control of the size of hugepage
being tested.
By default, spin up as many vCPUs as there are available to the selftest,
and distribute the work of dirtying each 4kb chunk of memory across all
vCPUs. Dirtying guest memory forces KVM to populate its page tables, and
also forces KVM to write back accessed/dirty information to struct page
when the guest memory is freed.
On x86, perform two passes with a MMU context reset between each pass to
coerce KVM into dropping all references to the MMU root, e.g. to emulate
a vCPU dropping the last reference. Perform both passes and all
rendezvous on all architectures in the hope that arm64 and s390x can gain
similar shenanigans in the future.
Measure and report the duration of each operation, which is helpful not
only to verify the test is working as intended, but also to easily
evaluate the performance differences different page sizes.
Provide command line options to limit the amount of guest memory, set the
size of each slot (i.e. of the host memory region), set the number of
vCPUs, and to enable usage of hugepages.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <
20220226001546.360188-29-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:45 +0000 (00:15 +0000)]
KVM: selftests: Define cpu_relax() helpers for s390 and x86
Add cpu_relax() for s390 and x86 for use in arch-agnostic tests. arm64
already defines its own version.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <
20220226001546.360188-28-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:44 +0000 (00:15 +0000)]
KVM: selftests: Split out helper to allocate guest mem via memfd
Extract the code for allocating guest memory via memfd out of
vm_userspace_mem_region_add() and into a new helper, kvm_memfd_alloc().
A future selftest to populate a guest with the maximum amount of guest
memory will abuse KVM's memslots to alias guest memory regions to a
single memfd-backed host region, i.e. needs to back a guest with memfd
memory without a 1:1 association between a memslot and a memfd instance.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <
20220226001546.360188-27-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:43 +0000 (00:15 +0000)]
KVM: selftests: Move raw KVM_SET_USER_MEMORY_REGION helper to utils
Move set_memory_region_test's KVM_SET_USER_MEMORY_REGION helper to KVM's
utils so that it can be used by other tests. Provide a raw version as
well as an assert-success version to reduce the amount of boilerplate
code need for basic usage.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <
20220226001546.360188-26-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:42 +0000 (00:15 +0000)]
KVM: x86/mmu: WARN on any attempt to atomically update REMOVED SPTE
Disallow calling tdp_mmu_set_spte_atomic() with a REMOVED "old" SPTE.
This solves a conundrum introduced by commit
3255530ab191 ("KVM: x86/mmu:
Automatically update iter->old_spte if cmpxchg fails"); if the helper
doesn't update old_spte in the REMOVED case, then theoretically the
caller could get stuck in an infinite loop as it will fail indefinitely
on the REMOVED SPTE. E.g. until recently, clear_dirty_gfn_range() didn't
check for a present SPTE and would have spun until getting rescheduled.
In practice, only the page fault path should "create" a new SPTE, all
other paths should only operate on existing, a.k.a. shadow present,
SPTEs. Now that the page fault path pre-checks for a REMOVED SPTE in all
cases, require all other paths to indirectly pre-check by verifying the
target SPTE is a shadow-present SPTE.
Note, this does not guarantee the actual SPTE isn't REMOVED, nor is that
scenario disallowed. The invariant is only that the caller mustn't
invoke tdp_mmu_set_spte_atomic() if the SPTE was REMOVED when last
observed by the caller.
Cc: David Matlack <dmatlack@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <
20220226001546.360188-25-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:41 +0000 (00:15 +0000)]
KVM: x86/mmu: Check for a REMOVED leaf SPTE before making the SPTE
Explicitly check for a REMOVED leaf SPTE prior to attempting to map
the final SPTE when handling a TDP MMU fault. Functionally, this is a
nop as tdp_mmu_set_spte_atomic() will eventually detect the frozen SPTE.
Pre-checking for a REMOVED SPTE is a minor optmization, but the real goal
is to allow tdp_mmu_set_spte_atomic() to have an invariant that the "old"
SPTE is never a REMOVED SPTE.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <
20220226001546.360188-24-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo Bonzini [Fri, 4 Mar 2022 16:43:13 +0000 (11:43 -0500)]
KVM: x86/mmu: Zap defunct roots via asynchronous worker
Zap defunct roots, a.k.a. roots that have been invalidated after their
last reference was initially dropped, asynchronously via the existing work
queue instead of forcing the work upon the unfortunate task that happened
to drop the last reference.
If a vCPU task drops the last reference, the vCPU is effectively blocked
by the host for the entire duration of the zap. If the root being zapped
happens be fully populated with 4kb leaf SPTEs, e.g. due to dirty logging
being active, the zap can take several hundred seconds. Unsurprisingly,
most guests are unhappy if a vCPU disappears for hundreds of seconds.
E.g. running a synthetic selftest that triggers a vCPU root zap with
~64tb of guest memory and 4kb SPTEs blocks the vCPU for 900+ seconds.
Offloading the zap to a worker drops the block time to <100ms.
There is an important nuance to this change. If the same work item
was queued twice before the work function has run, it would only
execute once and one reference would be leaked. Therefore, now that
queueing and flushing items is not anymore protected by kvm->slots_lock,
kvm_tdp_mmu_invalidate_all_roots() has to check root->role.invalid and
skip already invalid roots. On the other hand, kvm_mmu_zap_all_fast()
must return only after those skipped roots have been zapped as well.
These two requirements can be satisfied only if _all_ places that
change invalid to true now schedule the worker before releasing the
mmu_lock. There are just two, kvm_tdp_mmu_put_root() and
kvm_tdp_mmu_invalidate_all_roots().
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <
20220226001546.360188-23-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:39 +0000 (00:15 +0000)]
KVM: x86/mmu: Zap roots in two passes to avoid inducing RCU stalls
When zapping a TDP MMU root, perform the zap in two passes to avoid
zapping an entire top-level SPTE while holding RCU, which can induce RCU
stalls. In the first pass, zap SPTEs at PG_LEVEL_1G, and then
zap top-level entries in the second pass.
With 4-level paging, zapping a PGD that is fully populated with 4kb leaf
SPTEs take up to ~7 or so seconds (time varies based on kernel config,
number of (v)CPUs, etc...). With 5-level paging, that time can balloon
well into hundreds of seconds.
Before remote TLB flushes were omitted, the problem was even worse as
waiting for all active vCPUs to respond to the IPI introduced significant
overhead for VMs with large numbers of vCPUs.
By zapping 1gb SPTEs (both shadow pages and hugepages) in the first pass,
the amount of work that is done without dropping RCU protection is
strictly bounded, with the worst case latency for a single operation
being less than 100ms.
Zapping at 1gb in the first pass is not arbitrary. First and foremost,
KVM relies on being able to zap 1gb shadow pages in a single shot when
when repacing a shadow page with a hugepage. Zapping a 1gb shadow page
that is fully populated with 4kb dirty SPTEs also triggers the worst case
latency due writing back the struct page accessed/dirty bits for each 4kb
page, i.e. the two-pass approach is guaranteed to work so long as KVM can
cleany zap a 1gb shadow page.
rcu: INFO: rcu_sched self-detected stall on CPU
rcu: 52-....: (20999 ticks this GP) idle=7be/1/0x4000000000000000
softirq=15759/15759 fqs=5058
(t=21016 jiffies g=66453 q=238577)
NMI backtrace for cpu 52
Call Trace:
...
mark_page_accessed+0x266/0x2f0
kvm_set_pfn_accessed+0x31/0x40
handle_removed_tdp_mmu_page+0x259/0x2e0
__handle_changed_spte+0x223/0x2c0
handle_removed_tdp_mmu_page+0x1c1/0x2e0
__handle_changed_spte+0x223/0x2c0
handle_removed_tdp_mmu_page+0x1c1/0x2e0
__handle_changed_spte+0x223/0x2c0
zap_gfn_range+0x141/0x3b0
kvm_tdp_mmu_zap_invalidated_roots+0xc8/0x130
kvm_mmu_zap_all_fast+0x121/0x190
kvm_mmu_invalidate_zap_pages_in_memslot+0xe/0x10
kvm_page_track_flush_slot+0x5c/0x80
kvm_arch_flush_shadow_memslot+0xe/0x10
kvm_set_memslot+0x172/0x4e0
__kvm_set_memory_region+0x337/0x590
kvm_vm_ioctl+0x49c/0xf80
Reported-by: David Matlack <dmatlack@google.com>
Cc: Ben Gardon <bgardon@google.com>
Cc: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <
20220226001546.360188-22-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo Bonzini [Thu, 3 Mar 2022 06:50:21 +0000 (01:50 -0500)]
KVM: x86/mmu: Allow yielding when zapping GFNs for defunct TDP MMU root
Allow yielding when zapping SPTEs after the last reference to a valid
root is put. Because KVM must drop all SPTEs in response to relevant
mmu_notifier events, mark defunct roots invalid and reset their refcount
prior to zapping the root. Keeping the refcount elevated while the zap
is in-progress ensures the root is reachable via mmu_notifier until the
zap completes and the last reference to the invalid, defunct root is put.
Allowing kvm_tdp_mmu_put_root() to yield fixes soft lockup issues if the
root in being put has a massive paging structure, e.g. zapping a root
that is backed entirely by 4kb pages for a guest with 32tb of memory can
take hundreds of seconds to complete.
watchdog: BUG: soft lockup - CPU#49 stuck for 485s! [max_guest_memor:52368]
RIP: 0010:kvm_set_pfn_dirty+0x30/0x50 [kvm]
__handle_changed_spte+0x1b2/0x2f0 [kvm]
handle_removed_tdp_mmu_page+0x1a7/0x2b8 [kvm]
__handle_changed_spte+0x1f4/0x2f0 [kvm]
handle_removed_tdp_mmu_page+0x1a7/0x2b8 [kvm]
__handle_changed_spte+0x1f4/0x2f0 [kvm]
tdp_mmu_zap_root+0x307/0x4d0 [kvm]
kvm_tdp_mmu_put_root+0x7c/0xc0 [kvm]
kvm_mmu_free_roots+0x22d/0x350 [kvm]
kvm_mmu_reset_context+0x20/0x60 [kvm]
kvm_arch_vcpu_ioctl_set_sregs+0x5a/0xc0 [kvm]
kvm_vcpu_ioctl+0x5bd/0x710 [kvm]
__se_sys_ioctl+0x77/0xc0
__x64_sys_ioctl+0x1d/0x20
do_syscall_64+0x44/0xa0
entry_SYSCALL_64_after_hwframe+0x44/0xae
KVM currently doesn't put a root from a non-preemptible context, so other
than the mmu_notifier wrinkle, yielding when putting a root is safe.
Yield-unfriendly iteration uses for_each_tdp_mmu_root(), which doesn't
take a reference to each root (it requires mmu_lock be held for the
entire duration of the walk).
tdp_mmu_next_root() is used only by the yield-friendly iterator.
tdp_mmu_zap_root_work() is explicitly yield friendly.
kvm_mmu_free_roots() => mmu_free_root_page() is a much bigger fan-out,
but is still yield-friendly in all call sites, as all callers can be
traced back to some combination of vcpu_run(), kvm_destroy_vm(), and/or
kvm_create_vm().
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <
20220226001546.360188-21-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo Bonzini [Wed, 2 Mar 2022 17:02:07 +0000 (12:02 -0500)]
KVM: x86/mmu: Zap invalidated roots via asynchronous worker
Use the system worker threads to zap the roots invalidated
by the TDP MMU's "fast zap" mechanism, implemented by
kvm_tdp_mmu_invalidate_all_roots().
At this point, apart from allowing some parallelism in the zapping of
roots, the workqueue is a glorified linked list: work items are added and
flushed entirely within a single kvm->slots_lock critical section. However,
the workqueue fixes a latent issue where kvm_mmu_zap_all_invalidated_roots()
assumes that it owns a reference to all invalid roots; therefore, no
one can set the invalid bit outside kvm_mmu_zap_all_fast(). Putting the
invalidated roots on a linked list... erm, on a workqueue ensures that
tdp_mmu_zap_root_work() only puts back those extra references that
kvm_mmu_zap_all_invalidated_roots() had gifted to it.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:37 +0000 (00:15 +0000)]
KVM: x86/mmu: Defer TLB flush to caller when freeing TDP MMU shadow pages
Defer TLB flushes to the caller when freeing TDP MMU shadow pages instead
of immediately flushing. Because the shadow pages are freed in an RCU
callback, so long as at least one CPU holds RCU, all CPUs are protected.
For vCPUs running in the guest, i.e. consuming TLB entries, KVM only
needs to ensure the caller services the pending TLB flush before dropping
its RCU protections. I.e. use the caller's RCU as a proxy for all vCPUs
running in the guest.
Deferring the flushes allows batching flushes, e.g. when installing a
1gb hugepage and zapping a pile of SPs. And when zapping an entire root,
deferring flushes allows skipping the flush entirely (because flushes are
not needed in that case).
Avoiding flushes when zapping an entire root is especially important as
synchronizing with other CPUs via IPI after zapping every shadow page can
cause significant performance issues for large VMs. The issue is
exacerbated by KVM zapping entire top-level entries without dropping
RCU protection, which can lead to RCU stalls even when zapping roots
backing relatively "small" amounts of guest memory, e.g. 2tb. Removing
the IPI bottleneck largely mitigates the RCU issues, though it's likely
still a problem for 5-level paging. A future patch will further address
the problem by zapping roots in multiple passes to avoid holding RCU for
an extended duration.
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <
20220226001546.360188-20-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:36 +0000 (00:15 +0000)]
KVM: x86/mmu: Do remote TLB flush before dropping RCU in TDP MMU resched
When yielding in the TDP MMU iterator, service any pending TLB flush
before dropping RCU protections in anticipation of using the caller's RCU
"lock" as a proxy for vCPUs in the guest.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <
20220226001546.360188-19-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:35 +0000 (00:15 +0000)]
KVM: x86/mmu: Zap only TDP MMU leafs in kvm_zap_gfn_range()
Zap only leaf SPTEs in the TDP MMU's zap_gfn_range(), and rename various
functions accordingly. When removing mappings for functional correctness
(except for the stupid VFIO GPU passthrough memslots bug), zapping the
leaf SPTEs is sufficient as the paging structures themselves do not point
at guest memory and do not directly impact the final translation (in the
TDP MMU).
Note, this aligns the TDP MMU with the legacy/full MMU, which zaps only
the rmaps, a.k.a. leaf SPTEs, in kvm_zap_gfn_range() and
kvm_unmap_gfn_range().
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <
20220226001546.360188-18-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:34 +0000 (00:15 +0000)]
KVM: x86/mmu: Require mmu_lock be held for write to zap TDP MMU range
Now that all callers of zap_gfn_range() hold mmu_lock for write, drop
support for zapping with mmu_lock held for read. That all callers hold
mmu_lock for write isn't a random coincidence; now that the paths that
need to zap _everything_ have their own path, the only callers left are
those that need to zap for functional correctness. And when zapping is
required for functional correctness, mmu_lock must be held for write,
otherwise the caller has no guarantees about the state of the TDP MMU
page tables after it has run, e.g. the SPTE(s) it zapped can be
immediately replaced by a vCPU faulting in a page.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <
20220226001546.360188-17-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:33 +0000 (00:15 +0000)]
KVM: x86/mmu: Add dedicated helper to zap TDP MMU root shadow page
Add a dedicated helper for zapping a TDP MMU root, and use it in the three
flows that do "zap_all" and intentionally do not do a TLB flush if SPTEs
are zapped (zapping an entire root is safe if and only if it cannot be in
use by any vCPU). Because a TLB flush is never required, unconditionally
pass "false" to tdp_mmu_iter_cond_resched() when potentially yielding.
Opportunistically document why KVM must not yield when zapping roots that
are being zapped by kvm_tdp_mmu_put_root(), i.e. roots whose refcount has
reached zero, and further harden the flow to detect improper KVM behavior
with respect to roots that are supposed to be unreachable.
In addition to hardening zapping of roots, isolating zapping of roots
will allow future simplification of zap_gfn_range() by having it zap only
leaf SPTEs, and by removing its tricky "zap all" heuristic. By having
all paths that truly need to free _all_ SPs flow through the dedicated
root zapper, the generic zapper can be freed of those concerns.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <
20220226001546.360188-16-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:32 +0000 (00:15 +0000)]
KVM: x86/mmu: Skip remote TLB flush when zapping all of TDP MMU
Don't flush the TLBs when zapping all TDP MMU pages, as the only time KVM
uses the slow version of "zap everything" is when the VM is being
destroyed or the owning mm has exited. In either case, KVM_RUN is
unreachable for the VM, i.e. the guest TLB entries cannot be consumed.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <
20220226001546.360188-15-seanjc@google.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:31 +0000 (00:15 +0000)]
KVM: x86/mmu: Zap only the target TDP MMU shadow page in NX recovery
When recovering a potential hugepage that was shattered for the iTLB
multihit workaround, precisely zap only the target page instead of
iterating over the TDP MMU to find the SP that was passed in. This will
allow future simplification of zap_gfn_range() by having it zap only
leaf SPTEs.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <
20220226001546.360188-14-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:30 +0000 (00:15 +0000)]
KVM: x86/mmu: Refactor low-level TDP MMU set SPTE helper to take raw values
Refactor __tdp_mmu_set_spte() to work with raw values instead of a
tdp_iter objects so that a future patch can modify SPTEs without doing a
walk, and without having to synthesize a tdp_iter.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <
20220226001546.360188-13-seanjc@google.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:29 +0000 (00:15 +0000)]
KVM: x86/mmu: WARN if old _or_ new SPTE is REMOVED in non-atomic path
WARN if the new_spte being set by __tdp_mmu_set_spte() is a REMOVED_SPTE,
which is called out by the comment as being disallowed but not actually
checked. Keep the WARN on the old_spte as well, because overwriting a
REMOVED_SPTE in the non-atomic path is also disallowed (as evidence by
lack of splats with the existing WARN).
Fixes:
08f07c800e9d ("KVM: x86/mmu: Flush TLBs after zap in TDP MMU PF handler")
Cc: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <
20220226001546.360188-12-seanjc@google.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:28 +0000 (00:15 +0000)]
KVM: x86/mmu: Add helpers to read/write TDP MMU SPTEs and document RCU
Add helpers to read and write TDP MMU SPTEs instead of open coding
rcu_dereference() all over the place, and to provide a convenient
location to document why KVM doesn't exempt holding mmu_lock for write
from having to hold RCU (and any future changes to the rules).
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <
20220226001546.360188-11-seanjc@google.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:27 +0000 (00:15 +0000)]
KVM: x86/mmu: Drop RCU after processing each root in MMU notifier hooks
Drop RCU protection after processing each root when handling MMU notifier
hooks that aren't the "unmap" path, i.e. aren't zapping. Temporarily
drop RCU to let RCU do its thing between roots, and to make it clear that
there's no special behavior that relies on holding RCU across all roots.
Currently, the RCU protection is completely superficial, it's necessary
only to make rcu_dereference() of SPTE pointers happy. A future patch
will rely on holding RCU as a proxy for vCPUs in the guest, e.g. to
ensure shadow pages aren't freed before all vCPUs do a TLB flush (or
rather, acknowledge the need for a flush), but in that case RCU needs to
be held until the flush is complete if and only if the flush is needed
because a shadow page may have been removed. And except for the "unmap"
path, MMU notifier events cannot remove SPs (don't toggle PRESENT bit,
and can't change the PFN for a SP).
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <
20220226001546.360188-10-seanjc@google.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:26 +0000 (00:15 +0000)]
KVM: x86/mmu: Batch TLB flushes from TDP MMU for MMU notifier change_spte
Batch TLB flushes (with other MMUs) when handling ->change_spte()
notifications in the TDP MMU. The MMU notifier path in question doesn't
allow yielding and correcty flushes before dropping mmu_lock.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <
20220226001546.360188-9-seanjc@google.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:25 +0000 (00:15 +0000)]
KVM: x86/mmu: Check for !leaf=>leaf, not PFN change, in TDP MMU SP removal
Look for a !leaf=>leaf conversion instead of a PFN change when checking
if a SPTE change removed a TDP MMU shadow page. Convert the PFN check
into a WARN, as KVM should never change the PFN of a shadow page (except
when its being zapped or replaced).
From a purely theoretical perspective, it's not illegal to replace a SP
with a hugepage pointing at the same PFN. In practice, it's impossible
as that would require mapping guest memory overtop a kernel-allocated SP.
Either way, the check is odd.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <
20220226001546.360188-8-seanjc@google.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo Bonzini [Wed, 2 Mar 2022 13:51:05 +0000 (08:51 -0500)]
KVM: x86/mmu: do not allow readers to acquire references to invalid roots
Remove the "shared" argument of for_each_tdp_mmu_root_yield_safe, thus ensuring
that readers do not ever acquire a reference to an invalid root. After this
patch, all readers except kvm_tdp_mmu_zap_invalidated_roots() treat
refcount=0/valid, refcount=0/invalid and refcount=1/invalid in exactly the
same way. kvm_tdp_mmu_zap_invalidated_roots() is different but it also
does not acquire a reference to the invalid root, and it cannot see
refcount=0/invalid because it is guaranteed to run after
kvm_tdp_mmu_invalidate_all_roots().
Opportunistically add a lockdep assertion to the yield-safe iterator.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo Bonzini [Wed, 2 Mar 2022 13:44:22 +0000 (08:44 -0500)]
KVM: x86/mmu: only perform eager page splitting on valid roots
Eager page splitting is an optimization; it does not have to be performed on
invalid roots. It is also the only case in which a reader might acquire
a reference to an invalid root, so after this change we know that readers
will skip both dying and invalid roots.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:24 +0000 (00:15 +0000)]
KVM: x86/mmu: Require mmu_lock be held for write in unyielding root iter
Assert that mmu_lock is held for write by users of the yield-unfriendly
TDP iterator. The nature of a shared walk means that the caller needs to
play nice with other tasks modifying the page tables, which is more or
less the same thing as playing nice with yielding. Theoretically, KVM
could gain a flow where it could legitimately take mmu_lock for read in
a non-preemptible context, but that's highly unlikely and any such case
should be viewed with a fair amount of scrutiny.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <
20220226001546.360188-7-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:23 +0000 (00:15 +0000)]
KVM: x86/mmu: Document that zapping invalidated roots doesn't need to flush
Remove the misleading flush "handling" when zapping invalidated TDP MMU
roots, and document that flushing is unnecessary for all flavors of MMUs
when zapping invalid/obsolete roots/pages. The "handling" in the TDP MMU
is dead code, as zap_gfn_range() is called with shared=true, in which
case it will never return true due to the flushing being handled by
tdp_mmu_zap_spte_atomic().
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <
20220226001546.360188-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:22 +0000 (00:15 +0000)]
KVM: x86/mmu: Formalize TDP MMU's (unintended?) deferred TLB flush logic
Explicitly ignore the result of zap_gfn_range() when putting the last
reference to a TDP MMU root, and add a pile of comments to formalize the
TDP MMU's behavior of deferring TLB flushes to alloc/reuse. Note, this
only affects the !shared case, as zap_gfn_range() subtly never returns
true for "flush" as the flush is handled by tdp_mmu_zap_spte_atomic().
Putting the root without a flush is ok because even if there are stale
references to the root in the TLB, they are unreachable because KVM will
not run the guest with the same ASID without first flushing (where ASID
in this context refers to both SVM's explicit ASID and Intel's implicit
ASID that is constructed from VPID+PCID+EPT4A+etc...).
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <
20220226001546.360188-5-seanjc@google.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:21 +0000 (00:15 +0000)]
KVM: x86/mmu: Fix wrong/misleading comments in TDP MMU fast zap
Fix misleading and arguably wrong comments in the TDP MMU's fast zap
flow. The comments, and the fact that actually zapping invalid roots was
added separately, strongly suggests that zapping invalid roots is an
optimization and not required for correctness. That is a lie.
KVM _must_ zap invalid roots before returning from kvm_mmu_zap_all_fast(),
because when it's called from kvm_mmu_invalidate_zap_pages_in_memslot(),
KVM is relying on it to fully remove all references to the memslot. Once
the memslot is gone, KVM's mmu_notifier hooks will be unable to find the
stale references as the hva=>gfn translation is done via the memslots.
If KVM doesn't immediately zap SPTEs and userspace unmaps a range after
deleting a memslot, KVM will fail to zap in response to the mmu_notifier
due to not finding a memslot corresponding to the notifier's range, which
leads to a variation of use-after-free.
The other misleading comment (and code) explicitly states that roots
without a reference should be skipped. While that's technically true,
it's also extremely misleading as it should be impossible for KVM to
encounter a defunct root on the list while holding mmu_lock for write.
Opportunistically add a WARN to enforce that invariant.
Fixes:
b7cccd397f31 ("KVM: x86/mmu: Fast invalidation for TDP MMU")
Fixes:
4c6654bd160d ("KVM: x86/mmu: Tear down roots before kvm_mmu_zap_all_fast returns")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <
20220226001546.360188-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson [Sat, 26 Feb 2022 00:15:20 +0000 (00:15 +0000)]
KVM: x86/mmu: Check for present SPTE when clearing dirty bit in TDP MMU
Explicitly check for present SPTEs when clearing dirty bits in the TDP
MMU. This isn't strictly required for correctness, as setting the dirty
bit in a defunct SPTE will not change the SPTE from !PRESENT to PRESENT.
However, the guarded MMU_WARN_ON() in spte_ad_need_write_protect() would
complain if anyone actually turned on KVM's MMU debugging.
Fixes:
a6a0b05da9f3 ("kvm: x86/mmu: Support dirty logging for the TDP MMU")
Cc: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <
20220226001546.360188-3-seanjc@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>