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[34.82.80.254]) by smtp.gmail.com with ESMTPSA id d29sm4169033pfq.193.2021.07.27.08.36.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Jul 2021 08:36:40 -0700 (PDT) Date: Tue, 27 Jul 2021 15:36:37 +0000 From: David Matlack To: Mingwei Zhang Cc: Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Ben Gardon , Jing Zhang Subject: Re: [PATCH v2 3/3] KVM: x86/mmu: Add detailed page size stats Message-ID: References: <20210726175357.1572951-1-mizhang@google.com> <20210726175357.1572951-4-mizhang@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210726175357.1572951-4-mizhang@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 26, 2021 at 10:53:57AM -0700, Mingwei Zhang wrote: > Existing KVM code tracks the number of large pages regardless of their > sizes. Therefore, when large page of 1GB (or larger) is adopted, the > information becomes less useful because lpages counts a mix of 1G and 2M > pages. > > So remove the lpages since it is easy for user space to aggregate the info. > Instead, provide a comprehensive page stats of all sizes from 4K to 512G. > > Suggested-by: Ben Gardon > Suggested-by: Jing Zhang > Signed-off-by: Mingwei Zhang > --- > arch/x86/include/asm/kvm_host.h | 10 +++++++++- > arch/x86/kvm/mmu.h | 2 ++ > arch/x86/kvm/mmu/mmu.c | 32 +++++++++++++++++++------------- > arch/x86/kvm/mmu/tdp_mmu.c | 15 ++------------- > arch/x86/kvm/x86.c | 7 +++++-- > 5 files changed, 37 insertions(+), 29 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 974cbfb1eefe..2e4b6fd36e62 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -1206,9 +1206,17 @@ struct kvm_vm_stat { > u64 mmu_recycled; > u64 mmu_cache_miss; > u64 mmu_unsync; > - u64 lpages; > u64 nx_lpage_splits; > u64 max_mmu_page_hash_collisions; > + union { > + struct { > + atomic64_t pages_4k; > + atomic64_t pages_2m; > + atomic64_t pages_1g; > + atomic64_t pages_512g; > + }; > + atomic64_t pages[4]; > + } page_stats; > }; > > struct kvm_vcpu_stat { > diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h > index 83e6c6965f1e..ad5638815311 100644 > --- a/arch/x86/kvm/mmu.h > +++ b/arch/x86/kvm/mmu.h > @@ -240,4 +240,6 @@ static inline bool kvm_memslots_have_rmaps(struct kvm *kvm) > return smp_load_acquire(&kvm->arch.memslots_have_rmaps); > } > > +void kvm_update_page_stats(struct kvm *kvm, int level, int count); > + > #endif > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index 442cc554ebd6..7e0fc760739b 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -588,16 +588,22 @@ static bool mmu_spte_update(u64 *sptep, u64 new_spte) > return flush; > } > > +void kvm_update_page_stats(struct kvm *kvm, int level, int count) > +{ > + atomic64_add(count, &kvm->stat.page_stats.pages[level - 1]); > +} > + > /* > * Rules for using mmu_spte_clear_track_bits: > * It sets the sptep from present to nonpresent, and track the > * state bits, it is used to clear the last level sptep. > * Returns non-zero if the PTE was previously valid. > */ > -static int mmu_spte_clear_track_bits(u64 *sptep) > +static int mmu_spte_clear_track_bits(struct kvm *kvm, u64 *sptep) > { > kvm_pfn_t pfn; > u64 old_spte = *sptep; > + int level = sptep_to_sp(sptep)->role.level; > > if (!spte_has_volatile_bits(old_spte)) > __update_clear_spte_fast(sptep, 0ull); > @@ -607,6 +613,9 @@ static int mmu_spte_clear_track_bits(u64 *sptep) > if (!is_shadow_present_pte(old_spte)) > return 0; > > + if (is_last_spte(old_spte, level)) > + kvm_update_page_stats(kvm, level, -1); > + > pfn = spte_to_pfn(old_spte); > > /* > @@ -984,9 +993,10 @@ static void __pte_list_remove(u64 *spte, struct kvm_rmap_head *rmap_head) > } > } > > -static void pte_list_remove(struct kvm_rmap_head *rmap_head, u64 *sptep) > +static void pte_list_remove(struct kvm *kvm, struct kvm_rmap_head *rmap_head, > + u64 *sptep) > { > - mmu_spte_clear_track_bits(sptep); > + mmu_spte_clear_track_bits(kvm, sptep); > __pte_list_remove(sptep, rmap_head); > } > > @@ -1119,7 +1129,7 @@ static u64 *rmap_get_next(struct rmap_iterator *iter) > > static void drop_spte(struct kvm *kvm, u64 *sptep) > { > - if (mmu_spte_clear_track_bits(sptep)) > + if (mmu_spte_clear_track_bits(kvm, sptep)) > rmap_remove(kvm, sptep); > } > > @@ -1129,7 +1139,6 @@ static bool __drop_large_spte(struct kvm *kvm, u64 *sptep) > if (is_large_pte(*sptep)) { > WARN_ON(sptep_to_sp(sptep)->role.level == PG_LEVEL_4K); > drop_spte(kvm, sptep); > - --kvm->stat.lpages; > return true; > } > > @@ -1386,7 +1395,7 @@ static bool kvm_zap_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head, > while ((sptep = rmap_get_first(rmap_head, &iter))) { > rmap_printk("spte %p %llx.\n", sptep, *sptep); > > - pte_list_remove(rmap_head, sptep); > + pte_list_remove(kvm, rmap_head, sptep); > flush = true; > } > > @@ -1421,13 +1430,13 @@ static bool kvm_set_pte_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head, > need_flush = 1; > > if (pte_write(pte)) { > - pte_list_remove(rmap_head, sptep); > + pte_list_remove(kvm, rmap_head, sptep); > goto restart; > } else { > new_spte = kvm_mmu_changed_pte_notifier_make_spte( > *sptep, new_pfn); > > - mmu_spte_clear_track_bits(sptep); > + mmu_spte_clear_track_bits(kvm, sptep); > mmu_spte_set(sptep, new_spte); > } > } > @@ -2232,8 +2241,6 @@ static int mmu_page_zap_pte(struct kvm *kvm, struct kvm_mmu_page *sp, > if (is_shadow_present_pte(pte)) { > if (is_last_spte(pte, sp->role.level)) { > drop_spte(kvm, spte); > - if (is_large_pte(pte)) > - --kvm->stat.lpages; > } else { > child = to_shadow_page(pte & PT64_BASE_ADDR_MASK); > drop_parent_pte(child, spte); > @@ -2692,8 +2699,7 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep, > trace_kvm_mmu_set_spte(level, gfn, sptep); > > if (!was_rmapped) { > - if (is_large_pte(*sptep)) > - ++vcpu->kvm->stat.lpages; > + kvm_update_page_stats(vcpu->kvm, level, 1); > rmap_count = rmap_add(vcpu, sptep, gfn); > if (rmap_count > RMAP_RECYCLE_THRESHOLD) > rmap_recycle(vcpu, sptep, gfn); > @@ -5669,7 +5675,7 @@ static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm, > if (sp->role.direct && !kvm_is_reserved_pfn(pfn) && > sp->role.level < kvm_mmu_max_mapping_level(kvm, slot, sp->gfn, > pfn, PG_LEVEL_NUM)) { > - pte_list_remove(rmap_head, sptep); > + pte_list_remove(kvm, rmap_head, sptep); > > if (kvm_available_flush_tlb_with_range()) > kvm_flush_remote_tlbs_with_address(kvm, sp->gfn, > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > index cba2ab5db2a0..eae404c15364 100644 > --- a/arch/x86/kvm/mmu/tdp_mmu.c > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > @@ -413,7 +413,6 @@ static void __handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, > bool was_leaf = was_present && is_last_spte(old_spte, level); > bool is_leaf = is_present && is_last_spte(new_spte, level); > bool pfn_changed = spte_to_pfn(old_spte) != spte_to_pfn(new_spte); > - bool was_large, is_large; > > WARN_ON(level > PT64_ROOT_MAX_LEVEL); > WARN_ON(level < PG_LEVEL_4K); > @@ -472,18 +471,8 @@ static void __handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, > return; > } > > - /* > - * Update large page stats if a large page is being zapped, created, or > - * is replacing an existing shadow page. > - */ > - was_large = was_leaf && is_large_pte(old_spte); > - is_large = is_leaf && is_large_pte(new_spte); > - if (was_large != is_large) { > - if (was_large) > - atomic64_sub(1, (atomic64_t *)&kvm->stat.lpages); > - else > - atomic64_add(1, (atomic64_t *)&kvm->stat.lpages); > - } > + if (is_leaf != was_leaf) > + kvm_update_page_stats(kvm, level, is_leaf ? 1 : -1); > > if (was_leaf && is_dirty_spte(old_spte) && > (!is_present || !is_dirty_spte(new_spte) || pfn_changed)) > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 8166ad113fb2..3858d36d3c49 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -235,9 +235,12 @@ const struct _kvm_stats_desc kvm_vm_stats_desc[] = { > STATS_DESC_COUNTER(VM, mmu_recycled), > STATS_DESC_COUNTER(VM, mmu_cache_miss), > STATS_DESC_ICOUNTER(VM, mmu_unsync), > - STATS_DESC_ICOUNTER(VM, lpages), > STATS_DESC_ICOUNTER(VM, nx_lpage_splits), > - STATS_DESC_PCOUNTER(VM, max_mmu_page_hash_collisions) > + STATS_DESC_PCOUNTER(VM, max_mmu_page_hash_collisions), > + STATS_DESC_ICOUNTER(VM, page_stats.pages_4k), > + STATS_DESC_ICOUNTER(VM, page_stats.pages_2m), > + STATS_DESC_ICOUNTER(VM, page_stats.pages_1g), > + STATS_DESC_ICOUNTER(VM, page_stats.pages_512g) FYI this will make the stat names "page_stats.pages_4k", "page_stats.pages_2m", etc. Is that ok? If you want the stat names to be just "pages_4k", "pages_2m", etc. you can make the page_stats union anonymous. > }; > static_assert(ARRAY_SIZE(kvm_vm_stats_desc) == > sizeof(struct kvm_vm_stat) / sizeof(u64)); > -- > 2.32.0.432.gabb21c7263-goog >