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bh=VbatiMRsmAmXs4vvzOB1wH4t9q57JJ3mkBuPvNIsKCI=; b=qJinsBMDTCYazDCLd4G0F9mMgi0I1K0HYMl9VdD3eoMVHxmtER+AF4kFl5mjF8Et+0 aWBA5odEPHKLTJt9E3dNn2H8ByTMD+ygxzy3DHZqcyB301eHf19Dw8UKWnhBZW6srPMU dlMNReiPV8CuiFrK7UoqUAxYb9Mw/3Et3pdB1F/skld4IRGAS5aRsuNU1bvjbc6fmd1z I5x8P3lY6DKwSi8kBgYMLZffSrBrKNbs7H2nIK/VBQknUCQE6dUHe1qmako3vzMS91gT rP1rHPx5qRQBKtdNUhMb7scbAJXbVu4kbOmnju4h+UN3VtZOIHTriEaTJiy6/+o5yyoU L2mA== X-Gm-Message-State: AOAM531vF5QCCTxfhkv7CnZ2DTpmJgPsFhasV6wjiQHeQ/MNb27go7Oe 0MfIO2XmNO3aQ76yixuMjWTRq5V1LDrhMby3oolJ9A== X-Google-Smtp-Source: ABdhPJziQ6ODztQCpbyqJ6pgCmyWIQb7M9v95gDyRQspKyPkvXk8V/sTq4xygUHnDD4SO31Tkk5lKXsWLUf9xw8v+NM= X-Received: by 2002:ac2:442a:: with SMTP id w10mr1554388lfl.473.1628635881069; Tue, 10 Aug 2021 15:51:21 -0700 (PDT) MIME-Version: 1.0 References: <20210810223238.979194-1-jingzhangos@google.com> In-Reply-To: From: Jing Zhang Date: Tue, 10 Aug 2021 15:51:10 -0700 Message-ID: Subject: Re: [PATCH] KVM: stats: Add VM dirty_pages stats for the number of dirty pages To: Peter Feiner Cc: KVM , KVMPPC , Paolo Bonzini , Peter Shier , Oliver Upton , David Matlack , Ben Gardon Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, Aug 10, 2021 at 3:45 PM Peter Feiner wrote: > > On Tue, Aug 10, 2021 at 3:32 PM Jing Zhang wrote: > > > > Add a generic VM stats dirty_pages to record the number of dirty pages > > reflected in dirty_bitmap at the moment. > > > > Original-by: Peter Feiner > > Signed-off-by: Jing Zhang > > --- > > arch/powerpc/kvm/book3s_64_mmu_hv.c | 8 ++++++-- > > arch/powerpc/kvm/book3s_64_mmu_radix.c | 1 + > > arch/powerpc/kvm/book3s_hv_rm_mmu.c | 1 + > > include/linux/kvm_host.h | 3 ++- > > include/linux/kvm_types.h | 1 + > > virt/kvm/kvm_main.c | 26 +++++++++++++++++++++++--- > > 6 files changed, 34 insertions(+), 6 deletions(-) > > > > diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c > > index c63e263312a4..e4aafa10efa1 100644 > > --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c > > +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c > > @@ -1122,8 +1122,10 @@ long kvmppc_hv_get_dirty_log_hpt(struct kvm *kvm, > > * since we always put huge-page HPTEs in the rmap chain > > * corresponding to their page base address. > > */ > > - if (npages) > > + if (npages) { > > set_dirty_bits(map, i, npages); > > + kvm->stat.generic.dirty_pages += npages; > > + } > > ++rmapp; > > } > > preempt_enable(); > > @@ -1178,8 +1180,10 @@ void kvmppc_unpin_guest_page(struct kvm *kvm, void *va, unsigned long gpa, > > gfn = gpa >> PAGE_SHIFT; > > srcu_idx = srcu_read_lock(&kvm->srcu); > > memslot = gfn_to_memslot(kvm, gfn); > > - if (memslot && memslot->dirty_bitmap) > > + if (memslot && memslot->dirty_bitmap) { > > set_bit_le(gfn - memslot->base_gfn, memslot->dirty_bitmap); > > + ++kvm->stat.generic.dirty_pages; > > + } > > srcu_read_unlock(&kvm->srcu, srcu_idx); > > } > > > > diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c > > index b5905ae4377c..3a6cb3854a44 100644 > > --- a/arch/powerpc/kvm/book3s_64_mmu_radix.c > > +++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c > > @@ -1150,6 +1150,7 @@ long kvmppc_hv_get_dirty_log_radix(struct kvm *kvm, > > j = i + 1; > > if (npages) { > > set_dirty_bits(map, i, npages); > > + kvm->stat.generic.dirty_pages += npages; > > j = i + npages; > > } > > } > > diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c > > index 632b2545072b..16806bc473fa 100644 > > --- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c > > +++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c > > @@ -109,6 +109,7 @@ void kvmppc_update_dirty_map(const struct kvm_memory_slot *memslot, > > npages = (psize + PAGE_SIZE - 1) / PAGE_SIZE; > > gfn -= memslot->base_gfn; > > set_dirty_bits_atomic(memslot->dirty_bitmap, gfn, npages); > > + kvm->stat.generic.dirty_pages += npages; > > } > > EXPORT_SYMBOL_GPL(kvmppc_update_dirty_map); > > > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > > index f50bfcf225f0..1e8e66fb915b 100644 > > --- a/include/linux/kvm_host.h > > +++ b/include/linux/kvm_host.h > > @@ -1421,7 +1421,8 @@ struct _kvm_stats_desc { > > KVM_STATS_BASE_POW10, -9) > > > > #define KVM_GENERIC_VM_STATS() \ > > - STATS_DESC_COUNTER(VM_GENERIC, remote_tlb_flush) > > + STATS_DESC_COUNTER(VM_GENERIC, remote_tlb_flush), \ > > + STATS_DESC_COUNTER(VM_GENERIC, dirty_pages) > > > > #define KVM_GENERIC_VCPU_STATS() \ > > STATS_DESC_COUNTER(VCPU_GENERIC, halt_successful_poll), \ > > diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h > > index ed6a985c5680..6c05df00aebf 100644 > > --- a/include/linux/kvm_types.h > > +++ b/include/linux/kvm_types.h > > @@ -78,6 +78,7 @@ struct kvm_mmu_memory_cache { > > > > struct kvm_vm_stat_generic { > > u64 remote_tlb_flush; > > + u64 dirty_pages; > > }; > > > > struct kvm_vcpu_stat_generic { > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > > index a438a7a3774a..93f0ca2ea326 100644 > > --- a/virt/kvm/kvm_main.c > > +++ b/virt/kvm/kvm_main.c > > @@ -1228,6 +1228,19 @@ static int kvm_alloc_dirty_bitmap(struct kvm_memory_slot *memslot) > > return 0; > > } > > > > +static inline unsigned long hweight_dirty_bitmap( > > + struct kvm_memory_slot *memslot) > > +{ > > + unsigned long i; > > + unsigned long count = 0; > > + unsigned long n = kvm_dirty_bitmap_bytes(memslot); > > + > > + for (i = 0; i < n / sizeof(long); ++i) > > + count += hweight_long(memslot->dirty_bitmap[i]); > > + > > + return count; > > +} > > + > > /* > > * Delete a memslot by decrementing the number of used slots and shifting all > > * other entries in the array forward one spot. > > @@ -1612,6 +1625,7 @@ static int kvm_delete_memslot(struct kvm *kvm, > > if (r) > > return r; > > > > + kvm->stat.generic.dirty_pages -= hweight_dirty_bitmap(old); > > kvm_free_memslot(kvm, old); > > return 0; > > } > > @@ -1733,8 +1747,10 @@ int __kvm_set_memory_region(struct kvm *kvm, > > if (r) > > goto out_bitmap; > > > > - if (old.dirty_bitmap && !new.dirty_bitmap) > > + if (old.dirty_bitmap && !new.dirty_bitmap) { > > + kvm->stat.generic.dirty_pages -= hweight_dirty_bitmap(&old); > > kvm_destroy_dirty_bitmap(&old); > > + } > > return 0; > > > > out_bitmap: > > @@ -1895,6 +1911,7 @@ static int kvm_get_dirty_log_protect(struct kvm *kvm, struct kvm_dirty_log *log) > > offset = i * BITS_PER_LONG; > > kvm_arch_mmu_enable_log_dirty_pt_masked(kvm, memslot, > > offset, mask); > > + kvm->stat.generic.dirty_pages -= hweight_long(mask); > > } > > KVM_MMU_UNLOCK(kvm); > > } > > @@ -2012,6 +2029,7 @@ static int kvm_clear_dirty_log_protect(struct kvm *kvm, > > flush = true; > > kvm_arch_mmu_enable_log_dirty_pt_masked(kvm, memslot, > > offset, mask); > > + kvm->stat.generic.dirty_pages -= hweight_long(mask); > > } > > } > > KVM_MMU_UNLOCK(kvm); > > @@ -3062,11 +3080,13 @@ void mark_page_dirty_in_slot(struct kvm *kvm, > > unsigned long rel_gfn = gfn - memslot->base_gfn; > > u32 slot = (memslot->as_id << 16) | memslot->id; > > > > - if (kvm->dirty_ring_size) > > + if (kvm->dirty_ring_size) { > > kvm_dirty_ring_push(kvm_dirty_ring_get(kvm), > > slot, rel_gfn); > > - else > > + } else { > > set_bit_le(rel_gfn, memslot->dirty_bitmap); > > + ++kvm->stat.generic.dirty_pages; > > Couple of problems here: > > - Calls to mark_page_dirty_in_slot aren't serialized by the mmu_lock, > so these updates will race. > - The page might already be dirty in the bitmap, so you're potentially > double counting here > > You can fix both of these problems by changing set_bit_le to a > test_and_set_bit_le (might not be the function name -- but you get the > idea) and conditionally incrementing dirty_pages. Thanks Peter, will do that. > > > > + } > > } > > } > > EXPORT_SYMBOL_GPL(mark_page_dirty_in_slot); > > > > base-commit: d0732b0f8884d9cc0eca0082bbaef043f3fef7fb > > -- > > 2.32.0.605.g8dce9f2422-goog > > Jing From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jing Zhang Date: Tue, 10 Aug 2021 22:51:10 +0000 Subject: Re: [PATCH] KVM: stats: Add VM dirty_pages stats for the number of dirty pages Message-Id: List-Id: References: <20210810223238.979194-1-jingzhangos@google.com> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Peter Feiner Cc: KVM , KVMPPC , Paolo Bonzini , Peter Shier , Oliver Upton , David Matlack , Ben Gardon On Tue, Aug 10, 2021 at 3:45 PM Peter Feiner wrote: > > On Tue, Aug 10, 2021 at 3:32 PM Jing Zhang wrote: > > > > Add a generic VM stats dirty_pages to record the number of dirty pages > > reflected in dirty_bitmap at the moment. > > > > Original-by: Peter Feiner > > Signed-off-by: Jing Zhang > > --- > > arch/powerpc/kvm/book3s_64_mmu_hv.c | 8 ++++++-- > > arch/powerpc/kvm/book3s_64_mmu_radix.c | 1 + > > arch/powerpc/kvm/book3s_hv_rm_mmu.c | 1 + > > include/linux/kvm_host.h | 3 ++- > > include/linux/kvm_types.h | 1 + > > virt/kvm/kvm_main.c | 26 +++++++++++++++++++++++--- > > 6 files changed, 34 insertions(+), 6 deletions(-) > > > > diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c > > index c63e263312a4..e4aafa10efa1 100644 > > --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c > > +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c > > @@ -1122,8 +1122,10 @@ long kvmppc_hv_get_dirty_log_hpt(struct kvm *kvm, > > * since we always put huge-page HPTEs in the rmap chain > > * corresponding to their page base address. > > */ > > - if (npages) > > + if (npages) { > > set_dirty_bits(map, i, npages); > > + kvm->stat.generic.dirty_pages += npages; > > + } > > ++rmapp; > > } > > preempt_enable(); > > @@ -1178,8 +1180,10 @@ void kvmppc_unpin_guest_page(struct kvm *kvm, void *va, unsigned long gpa, > > gfn = gpa >> PAGE_SHIFT; > > srcu_idx = srcu_read_lock(&kvm->srcu); > > memslot = gfn_to_memslot(kvm, gfn); > > - if (memslot && memslot->dirty_bitmap) > > + if (memslot && memslot->dirty_bitmap) { > > set_bit_le(gfn - memslot->base_gfn, memslot->dirty_bitmap); > > + ++kvm->stat.generic.dirty_pages; > > + } > > srcu_read_unlock(&kvm->srcu, srcu_idx); > > } > > > > diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c > > index b5905ae4377c..3a6cb3854a44 100644 > > --- a/arch/powerpc/kvm/book3s_64_mmu_radix.c > > +++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c > > @@ -1150,6 +1150,7 @@ long kvmppc_hv_get_dirty_log_radix(struct kvm *kvm, > > j = i + 1; > > if (npages) { > > set_dirty_bits(map, i, npages); > > + kvm->stat.generic.dirty_pages += npages; > > j = i + npages; > > } > > } > > diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c > > index 632b2545072b..16806bc473fa 100644 > > --- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c > > +++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c > > @@ -109,6 +109,7 @@ void kvmppc_update_dirty_map(const struct kvm_memory_slot *memslot, > > npages = (psize + PAGE_SIZE - 1) / PAGE_SIZE; > > gfn -= memslot->base_gfn; > > set_dirty_bits_atomic(memslot->dirty_bitmap, gfn, npages); > > + kvm->stat.generic.dirty_pages += npages; > > } > > EXPORT_SYMBOL_GPL(kvmppc_update_dirty_map); > > > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > > index f50bfcf225f0..1e8e66fb915b 100644 > > --- a/include/linux/kvm_host.h > > +++ b/include/linux/kvm_host.h > > @@ -1421,7 +1421,8 @@ struct _kvm_stats_desc { > > KVM_STATS_BASE_POW10, -9) > > > > #define KVM_GENERIC_VM_STATS() \ > > - STATS_DESC_COUNTER(VM_GENERIC, remote_tlb_flush) > > + STATS_DESC_COUNTER(VM_GENERIC, remote_tlb_flush), \ > > + STATS_DESC_COUNTER(VM_GENERIC, dirty_pages) > > > > #define KVM_GENERIC_VCPU_STATS() \ > > STATS_DESC_COUNTER(VCPU_GENERIC, halt_successful_poll), \ > > diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h > > index ed6a985c5680..6c05df00aebf 100644 > > --- a/include/linux/kvm_types.h > > +++ b/include/linux/kvm_types.h > > @@ -78,6 +78,7 @@ struct kvm_mmu_memory_cache { > > > > struct kvm_vm_stat_generic { > > u64 remote_tlb_flush; > > + u64 dirty_pages; > > }; > > > > struct kvm_vcpu_stat_generic { > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > > index a438a7a3774a..93f0ca2ea326 100644 > > --- a/virt/kvm/kvm_main.c > > +++ b/virt/kvm/kvm_main.c > > @@ -1228,6 +1228,19 @@ static int kvm_alloc_dirty_bitmap(struct kvm_memory_slot *memslot) > > return 0; > > } > > > > +static inline unsigned long hweight_dirty_bitmap( > > + struct kvm_memory_slot *memslot) > > +{ > > + unsigned long i; > > + unsigned long count = 0; > > + unsigned long n = kvm_dirty_bitmap_bytes(memslot); > > + > > + for (i = 0; i < n / sizeof(long); ++i) > > + count += hweight_long(memslot->dirty_bitmap[i]); > > + > > + return count; > > +} > > + > > /* > > * Delete a memslot by decrementing the number of used slots and shifting all > > * other entries in the array forward one spot. > > @@ -1612,6 +1625,7 @@ static int kvm_delete_memslot(struct kvm *kvm, > > if (r) > > return r; > > > > + kvm->stat.generic.dirty_pages -= hweight_dirty_bitmap(old); > > kvm_free_memslot(kvm, old); > > return 0; > > } > > @@ -1733,8 +1747,10 @@ int __kvm_set_memory_region(struct kvm *kvm, > > if (r) > > goto out_bitmap; > > > > - if (old.dirty_bitmap && !new.dirty_bitmap) > > + if (old.dirty_bitmap && !new.dirty_bitmap) { > > + kvm->stat.generic.dirty_pages -= hweight_dirty_bitmap(&old); > > kvm_destroy_dirty_bitmap(&old); > > + } > > return 0; > > > > out_bitmap: > > @@ -1895,6 +1911,7 @@ static int kvm_get_dirty_log_protect(struct kvm *kvm, struct kvm_dirty_log *log) > > offset = i * BITS_PER_LONG; > > kvm_arch_mmu_enable_log_dirty_pt_masked(kvm, memslot, > > offset, mask); > > + kvm->stat.generic.dirty_pages -= hweight_long(mask); > > } > > KVM_MMU_UNLOCK(kvm); > > } > > @@ -2012,6 +2029,7 @@ static int kvm_clear_dirty_log_protect(struct kvm *kvm, > > flush = true; > > kvm_arch_mmu_enable_log_dirty_pt_masked(kvm, memslot, > > offset, mask); > > + kvm->stat.generic.dirty_pages -= hweight_long(mask); > > } > > } > > KVM_MMU_UNLOCK(kvm); > > @@ -3062,11 +3080,13 @@ void mark_page_dirty_in_slot(struct kvm *kvm, > > unsigned long rel_gfn = gfn - memslot->base_gfn; > > u32 slot = (memslot->as_id << 16) | memslot->id; > > > > - if (kvm->dirty_ring_size) > > + if (kvm->dirty_ring_size) { > > kvm_dirty_ring_push(kvm_dirty_ring_get(kvm), > > slot, rel_gfn); > > - else > > + } else { > > set_bit_le(rel_gfn, memslot->dirty_bitmap); > > + ++kvm->stat.generic.dirty_pages; > > Couple of problems here: > > - Calls to mark_page_dirty_in_slot aren't serialized by the mmu_lock, > so these updates will race. > - The page might already be dirty in the bitmap, so you're potentially > double counting here > > You can fix both of these problems by changing set_bit_le to a > test_and_set_bit_le (might not be the function name -- but you get the > idea) and conditionally incrementing dirty_pages. Thanks Peter, will do that. > > > > + } > > } > > } > > EXPORT_SYMBOL_GPL(mark_page_dirty_in_slot); > > > > base-commit: d0732b0f8884d9cc0eca0082bbaef043f3fef7fb > > -- > > 2.32.0.605.g8dce9f2422-goog > > Jing