From 190df4a212a708fdd18f6cabfdd82594c91fdf25 Mon Sep 17 00:00:00 2001 From: Claudio Imbrenda Date: Thu, 4 Aug 2016 17:54:42 +0200 Subject: [PATCH] KVM: s390: CMMA tracking, ESSA emulation, migration mode * Add a migration state bitmap to keep track of which pages have dirty CMMA information. * Disable CMMA by default, so we can track if it's used or not. Enable it on first use like we do for storage keys (unless we are doing a migration). * Creates a VM attribute to enter and leave migration mode. * In migration mode, CMMA is disabled in the SIE block, so ESSA is always interpreted and emulated in software. * Free the migration state on VM destroy. Signed-off-by: Claudio Imbrenda Acked-by: Cornelia Huck Reviewed-by: Christian Borntraeger Signed-off-by: Christian Borntraeger --- Documentation/virtual/kvm/devices/vm.txt | 33 +++++++ arch/s390/include/asm/kvm_host.h | 9 ++ arch/s390/include/uapi/asm/kvm.h | 6 ++ arch/s390/kvm/kvm-s390.c | 159 ++++++++++++++++++++++++++++++- arch/s390/kvm/priv.c | 103 +++++++++++++++++++- 5 files changed, 304 insertions(+), 6 deletions(-) diff --git a/Documentation/virtual/kvm/devices/vm.txt b/Documentation/virtual/kvm/devices/vm.txt index 575ccb0..903fc92 100644 --- a/Documentation/virtual/kvm/devices/vm.txt +++ b/Documentation/virtual/kvm/devices/vm.txt @@ -222,3 +222,36 @@ Allows user space to disable dea key wrapping, clearing the wrapping key. Parameters: none Returns: 0 + +5. GROUP: KVM_S390_VM_MIGRATION +Architectures: s390 + +5.1. ATTRIBUTE: KVM_S390_VM_MIGRATION_STOP (w/o) + +Allows userspace to stop migration mode, needed for PGSTE migration. +Setting this attribute when migration mode is not active will have no +effects. + +Parameters: none +Returns: 0 + +5.2. ATTRIBUTE: KVM_S390_VM_MIGRATION_START (w/o) + +Allows userspace to start migration mode, needed for PGSTE migration. +Setting this attribute when migration mode is already active will have +no effects. + +Parameters: none +Returns: -ENOMEM if there is not enough free memory to start migration mode + -EINVAL if the state of the VM is invalid (e.g. no memory defined) + 0 in case of success. + +5.3. ATTRIBUTE: KVM_S390_VM_MIGRATION_STATUS (r/o) + +Allows userspace to query the status of migration mode. + +Parameters: address of a buffer in user space to store the data (u64) to; + the data itself is either 0 if migration mode is disabled or 1 + if it is enabled +Returns: -EFAULT if the given address is not accessible from kernel space + 0 in case of success. diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h index 426614a..a8cafed 100644 --- a/arch/s390/include/asm/kvm_host.h +++ b/arch/s390/include/asm/kvm_host.h @@ -45,6 +45,8 @@ #define KVM_REQ_ENABLE_IBS 8 #define KVM_REQ_DISABLE_IBS 9 #define KVM_REQ_ICPT_OPEREXC 10 +#define KVM_REQ_START_MIGRATION 11 +#define KVM_REQ_STOP_MIGRATION 12 #define SIGP_CTRL_C 0x80 #define SIGP_CTRL_SCN_MASK 0x3f @@ -691,6 +693,12 @@ struct kvm_s390_vsie { struct page *pages[KVM_MAX_VCPUS]; }; +struct kvm_s390_migration_state { + unsigned long bitmap_size; /* in bits (number of guest pages) */ + atomic64_t dirty_pages; /* number of dirty pages */ + unsigned long *pgste_bitmap; +}; + struct kvm_arch{ void *sca; int use_esca; @@ -718,6 +726,7 @@ struct kvm_arch{ struct kvm_s390_crypto crypto; struct kvm_s390_vsie vsie; u64 epoch; + struct kvm_s390_migration_state *migration_state; /* subset of available cpu features enabled by user space */ DECLARE_BITMAP(cpu_feat, KVM_S390_VM_CPU_FEAT_NR_BITS); }; diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h index 3dd2a1d..d6879a9 100644 --- a/arch/s390/include/uapi/asm/kvm.h +++ b/arch/s390/include/uapi/asm/kvm.h @@ -70,6 +70,7 @@ struct kvm_s390_io_adapter_req { #define KVM_S390_VM_TOD 1 #define KVM_S390_VM_CRYPTO 2 #define KVM_S390_VM_CPU_MODEL 3 +#define KVM_S390_VM_MIGRATION 4 /* kvm attributes for mem_ctrl */ #define KVM_S390_VM_MEM_ENABLE_CMMA 0 @@ -151,6 +152,11 @@ struct kvm_s390_vm_cpu_subfunc { #define KVM_S390_VM_CRYPTO_DISABLE_AES_KW 2 #define KVM_S390_VM_CRYPTO_DISABLE_DEA_KW 3 +/* kvm attributes for migration mode */ +#define KVM_S390_VM_MIGRATION_STOP 0 +#define KVM_S390_VM_MIGRATION_START 1 +#define KVM_S390_VM_MIGRATION_STATUS 2 + /* for KVM_GET_REGS and KVM_SET_REGS */ struct kvm_regs { /* general purpose regs for s390 */ diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 689ac48..c2b3914 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -31,6 +31,7 @@ #include #include +#include #include #include #include @@ -750,6 +751,129 @@ static int kvm_s390_vm_set_crypto(struct kvm *kvm, struct kvm_device_attr *attr) return 0; } +static void kvm_s390_sync_request_broadcast(struct kvm *kvm, int req) +{ + int cx; + struct kvm_vcpu *vcpu; + + kvm_for_each_vcpu(cx, vcpu, kvm) + kvm_s390_sync_request(req, vcpu); +} + +/* + * Must be called with kvm->srcu held to avoid races on memslots, and with + * kvm->lock to avoid races with ourselves and kvm_s390_vm_stop_migration. + */ +static int kvm_s390_vm_start_migration(struct kvm *kvm) +{ + struct kvm_s390_migration_state *mgs; + struct kvm_memory_slot *ms; + /* should be the only one */ + struct kvm_memslots *slots; + unsigned long ram_pages; + int slotnr; + + /* migration mode already enabled */ + if (kvm->arch.migration_state) + return 0; + + slots = kvm_memslots(kvm); + if (!slots || !slots->used_slots) + return -EINVAL; + + mgs = kzalloc(sizeof(*mgs), GFP_KERNEL); + if (!mgs) + return -ENOMEM; + kvm->arch.migration_state = mgs; + + if (kvm->arch.use_cmma) { + /* + * Get the last slot. They should be sorted by base_gfn, so the + * last slot is also the one at the end of the address space. + * We have verified above that at least one slot is present. + */ + ms = slots->memslots + slots->used_slots - 1; + /* round up so we only use full longs */ + ram_pages = roundup(ms->base_gfn + ms->npages, BITS_PER_LONG); + /* allocate enough bytes to store all the bits */ + mgs->pgste_bitmap = vmalloc(ram_pages / 8); + if (!mgs->pgste_bitmap) { + kfree(mgs); + kvm->arch.migration_state = NULL; + return -ENOMEM; + } + + mgs->bitmap_size = ram_pages; + atomic64_set(&mgs->dirty_pages, ram_pages); + /* mark all the pages in active slots as dirty */ + for (slotnr = 0; slotnr < slots->used_slots; slotnr++) { + ms = slots->memslots + slotnr; + bitmap_set(mgs->pgste_bitmap, ms->base_gfn, ms->npages); + } + + kvm_s390_sync_request_broadcast(kvm, KVM_REQ_START_MIGRATION); + } + return 0; +} + +/* + * Must be called with kvm->lock to avoid races with ourselves and + * kvm_s390_vm_start_migration. + */ +static int kvm_s390_vm_stop_migration(struct kvm *kvm) +{ + struct kvm_s390_migration_state *mgs; + + /* migration mode already disabled */ + if (!kvm->arch.migration_state) + return 0; + mgs = kvm->arch.migration_state; + kvm->arch.migration_state = NULL; + + if (kvm->arch.use_cmma) { + kvm_s390_sync_request_broadcast(kvm, KVM_REQ_STOP_MIGRATION); + vfree(mgs->pgste_bitmap); + } + kfree(mgs); + return 0; +} + +static int kvm_s390_vm_set_migration(struct kvm *kvm, + struct kvm_device_attr *attr) +{ + int idx, res = -ENXIO; + + mutex_lock(&kvm->lock); + switch (attr->attr) { + case KVM_S390_VM_MIGRATION_START: + idx = srcu_read_lock(&kvm->srcu); + res = kvm_s390_vm_start_migration(kvm); + srcu_read_unlock(&kvm->srcu, idx); + break; + case KVM_S390_VM_MIGRATION_STOP: + res = kvm_s390_vm_stop_migration(kvm); + break; + default: + break; + } + mutex_unlock(&kvm->lock); + + return res; +} + +static int kvm_s390_vm_get_migration(struct kvm *kvm, + struct kvm_device_attr *attr) +{ + u64 mig = (kvm->arch.migration_state != NULL); + + if (attr->attr != KVM_S390_VM_MIGRATION_STATUS) + return -ENXIO; + + if (copy_to_user((void __user *)attr->addr, &mig, sizeof(mig))) + return -EFAULT; + return 0; +} + static int kvm_s390_set_tod_high(struct kvm *kvm, struct kvm_device_attr *attr) { u8 gtod_high; @@ -1090,6 +1214,9 @@ static int kvm_s390_vm_set_attr(struct kvm *kvm, struct kvm_device_attr *attr) case KVM_S390_VM_CRYPTO: ret = kvm_s390_vm_set_crypto(kvm, attr); break; + case KVM_S390_VM_MIGRATION: + ret = kvm_s390_vm_set_migration(kvm, attr); + break; default: ret = -ENXIO; break; @@ -1112,6 +1239,9 @@ static int kvm_s390_vm_get_attr(struct kvm *kvm, struct kvm_device_attr *attr) case KVM_S390_VM_CPU_MODEL: ret = kvm_s390_get_cpu_model(kvm, attr); break; + case KVM_S390_VM_MIGRATION: + ret = kvm_s390_vm_get_migration(kvm, attr); + break; default: ret = -ENXIO; break; @@ -1179,6 +1309,9 @@ static int kvm_s390_vm_has_attr(struct kvm *kvm, struct kvm_device_attr *attr) break; } break; + case KVM_S390_VM_MIGRATION: + ret = 0; + break; default: ret = -ENXIO; break; @@ -1633,6 +1766,10 @@ void kvm_arch_destroy_vm(struct kvm *kvm) kvm_s390_destroy_adapters(kvm); kvm_s390_clear_float_irqs(kvm); kvm_s390_vsie_destroy(kvm); + if (kvm->arch.migration_state) { + vfree(kvm->arch.migration_state->pgste_bitmap); + kfree(kvm->arch.migration_state); + } KVM_EVENT(3, "vm 0x%pK destroyed", kvm); } @@ -1977,7 +2114,6 @@ int kvm_s390_vcpu_setup_cmma(struct kvm_vcpu *vcpu) if (!vcpu->arch.sie_block->cbrlo) return -ENOMEM; - vcpu->arch.sie_block->ecb2 |= ECB2_CMMA; vcpu->arch.sie_block->ecb2 &= ~ECB2_PFMFI; return 0; } @@ -2489,6 +2625,27 @@ retry: goto retry; } + if (kvm_check_request(KVM_REQ_START_MIGRATION, vcpu)) { + /* + * Disable CMMA virtualization; we will emulate the ESSA + * instruction manually, in order to provide additional + * functionalities needed for live migration. + */ + vcpu->arch.sie_block->ecb2 &= ~ECB2_CMMA; + goto retry; + } + + if (kvm_check_request(KVM_REQ_STOP_MIGRATION, vcpu)) { + /* + * Re-enable CMMA virtualization if CMMA is available and + * was used. + */ + if ((vcpu->kvm->arch.use_cmma) && + (vcpu->kvm->mm->context.use_cmma)) + vcpu->arch.sie_block->ecb2 |= ECB2_CMMA; + goto retry; + } + /* nothing to do, just clear the request */ kvm_clear_request(KVM_REQ_UNHALT, vcpu); diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c index c03106c..a226c45 100644 --- a/arch/s390/kvm/priv.c +++ b/arch/s390/kvm/priv.c @@ -24,6 +24,7 @@ #include #include #include +#include #include #include #include @@ -949,13 +950,72 @@ static int handle_pfmf(struct kvm_vcpu *vcpu) return 0; } +static inline int do_essa(struct kvm_vcpu *vcpu, const int orc) +{ + struct kvm_s390_migration_state *ms = vcpu->kvm->arch.migration_state; + int r1, r2, nappended, entries; + unsigned long gfn, hva, res, pgstev, ptev; + unsigned long *cbrlo; + + /* + * We don't need to set SD.FPF.SK to 1 here, because if we have a + * machine check here we either handle it or crash + */ + + kvm_s390_get_regs_rre(vcpu, &r1, &r2); + gfn = vcpu->run->s.regs.gprs[r2] >> PAGE_SHIFT; + hva = gfn_to_hva(vcpu->kvm, gfn); + entries = (vcpu->arch.sie_block->cbrlo & ~PAGE_MASK) >> 3; + + if (kvm_is_error_hva(hva)) + return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING); + + nappended = pgste_perform_essa(vcpu->kvm->mm, hva, orc, &ptev, &pgstev); + if (nappended < 0) { + res = orc ? 0x10 : 0; + vcpu->run->s.regs.gprs[r1] = res; /* Exception Indication */ + return 0; + } + res = (pgstev & _PGSTE_GPS_USAGE_MASK) >> 22; + /* + * Set the block-content state part of the result. 0 means resident, so + * nothing to do if the page is valid. 2 is for preserved pages + * (non-present and non-zero), and 3 for zero pages (non-present and + * zero). + */ + if (ptev & _PAGE_INVALID) { + res |= 2; + if (pgstev & _PGSTE_GPS_ZERO) + res |= 1; + } + vcpu->run->s.regs.gprs[r1] = res; + /* + * It is possible that all the normal 511 slots were full, in which case + * we will now write in the 512th slot, which is reserved for host use. + * In both cases we let the normal essa handling code process all the + * slots, including the reserved one, if needed. + */ + if (nappended > 0) { + cbrlo = phys_to_virt(vcpu->arch.sie_block->cbrlo & PAGE_MASK); + cbrlo[entries] = gfn << PAGE_SHIFT; + } + + if (orc) { + /* increment only if we are really flipping the bit to 1 */ + if (!test_and_set_bit(gfn, ms->pgste_bitmap)) + atomic64_inc(&ms->dirty_pages); + } + + return nappended; +} + static int handle_essa(struct kvm_vcpu *vcpu) { /* entries expected to be 1FF */ int entries = (vcpu->arch.sie_block->cbrlo & ~PAGE_MASK) >> 3; unsigned long *cbrlo; struct gmap *gmap; - int i; + int i, orc; VCPU_EVENT(vcpu, 4, "ESSA: release %d pages", entries); gmap = vcpu->arch.gmap; @@ -965,12 +1025,45 @@ static int handle_essa(struct kvm_vcpu *vcpu) if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE) return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP); - - if (((vcpu->arch.sie_block->ipb & 0xf0000000) >> 28) > 6) + /* Check for invalid operation request code */ + orc = (vcpu->arch.sie_block->ipb & 0xf0000000) >> 28; + if (orc > ESSA_MAX) return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION); - /* Retry the ESSA instruction */ - kvm_s390_retry_instr(vcpu); + if (likely(!vcpu->kvm->arch.migration_state)) { + /* + * CMMA is enabled in the KVM settings, but is disabled in + * the SIE block and in the mm_context, and we are not doing + * a migration. Enable CMMA in the mm_context. + * Since we need to take a write lock to write to the context + * to avoid races with storage keys handling, we check if the + * value really needs to be written to; if the value is + * already correct, we do nothing and avoid the lock. + */ + if (vcpu->kvm->mm->context.use_cmma == 0) { + down_write(&vcpu->kvm->mm->mmap_sem); + vcpu->kvm->mm->context.use_cmma = 1; + up_write(&vcpu->kvm->mm->mmap_sem); + } + /* + * If we are here, we are supposed to have CMMA enabled in + * the SIE block. Enabling CMMA works on a per-CPU basis, + * while the context use_cmma flag is per process. + * It's possible that the context flag is enabled and the + * SIE flag is not, so we set the flag always; if it was + * already set, nothing changes, otherwise we enable it + * on this CPU too. + */ + vcpu->arch.sie_block->ecb2 |= ECB2_CMMA; + /* Retry the ESSA instruction */ + kvm_s390_retry_instr(vcpu); + } else { + /* Account for the possible extra cbrl entry */ + i = do_essa(vcpu, orc); + if (i < 0) + return i; + entries += i; + } vcpu->arch.sie_block->cbrlo &= PAGE_MASK; /* reset nceo */ cbrlo = phys_to_virt(vcpu->arch.sie_block->cbrlo); down_read(&gmap->mm->mmap_sem); -- 2.7.4