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Peter Anvin" , Hugh Dickins , Jeff Layton , "J . Bruce Fields" , Andrew Morton , Shuah Khan , Mike Rapoport , Steven Price , "Maciej S . Szmigiero" , Vlastimil Babka , Vishal Annapurve , Yu Zhang , Chao Peng , "Kirill A . Shutemov" , luto@kernel.org, jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com, david@redhat.com, aarcange@redhat.com, ddutile@redhat.com, dhildenb@redhat.com, Quentin Perret , tabba@google.com, Michael Roth , mhocko@suse.com, wei.w.wang@intel.com Subject: [PATCH v10 7/9] KVM: Update lpage info when private/shared memory are mixed Date: Fri, 2 Dec 2022 14:13:45 +0800 Message-Id: <20221202061347.1070246-8-chao.p.peng@linux.intel.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20221202061347.1070246-1-chao.p.peng@linux.intel.com> References: <20221202061347.1070246-1-chao.p.peng@linux.intel.com> MIME-Version: 1.0 X-Stat-Signature: 5qkqwst783nxmb5c79wuwcjk75g8wemm X-Spamd-Result: default: False [-0.20 / 9.00]; BAYES_HAM(-3.00)[100.00%]; R_MISSING_CHARSET(2.50)[]; MID_CONTAINS_FROM(1.00)[]; DMARC_POLICY_ALLOW(-0.50)[intel.com,none]; R_DKIM_ALLOW(-0.20)[intel.com:s=Intel]; MIME_GOOD(-0.10)[text/plain]; RCVD_NO_TLS_LAST(0.10)[]; RCPT_COUNT_TWELVE(0.00)[49]; R_SPF_NA(0.00)[no SPF record]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_SOME(0.00)[]; MIME_TRACE(0.00)[0:+]; FROM_HAS_DN(0.00)[]; DKIM_TRACE(0.00)[intel.com:+]; TO_DN_SOME(0.00)[]; RCVD_COUNT_THREE(0.00)[3]; ARC_SIGNED(0.00)[hostedemail.com:s=arc-20220608:i=1]; ARC_NA(0.00)[] X-Rspamd-Queue-Id: 4FF762000B X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1669961976-486847 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: A large page with mixed private/shared subpages can't be mapped as large page since its sub private/shared pages are from different memory backends and may also treated by architecture differently. When private/shared memory are mixed in a large page, the current lpage_info is not sufficient to decide whether the page can be mapped as large page or not and additional private/shared mixed information is needed. Tracking this 'mixed' information with the current 'count' like disallow_lpage is a bit challenge so reserve a bit in 'disallow_lpage' to indicate a large page has mixed private/share subpages and update this 'mixed' bit whenever the memory attribute is changed between private and shared. Signed-off-by: Chao Peng --- arch/x86/include/asm/kvm_host.h | 8 ++ arch/x86/kvm/mmu/mmu.c | 134 +++++++++++++++++++++++++++++++- arch/x86/kvm/x86.c | 2 + include/linux/kvm_host.h | 19 +++++ virt/kvm/kvm_main.c | 9 ++- 5 files changed, 169 insertions(+), 3 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 283cbb83d6ae..7772ab37ac89 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -38,6 +38,7 @@ #include #define __KVM_HAVE_ARCH_VCPU_DEBUGFS +#define __KVM_HAVE_ARCH_SET_MEMORY_ATTRIBUTES #define KVM_MAX_VCPUS 1024 @@ -1011,6 +1012,13 @@ struct kvm_vcpu_arch { #endif }; +/* + * Use a bit in disallow_lpage to indicate private/shared pages mixed at the + * level. The remaining bits are used as a reference count. + */ +#define KVM_LPAGE_PRIVATE_SHARED_MIXED (1U << 31) +#define KVM_LPAGE_COUNT_MAX ((1U << 31) - 1) + struct kvm_lpage_info { int disallow_lpage; }; diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index e2c70b5afa3e..2190fd8c95c0 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -763,11 +763,16 @@ static void update_gfn_disallow_lpage_count(const struct kvm_memory_slot *slot, { struct kvm_lpage_info *linfo; int i; + int disallow_count; for (i = PG_LEVEL_2M; i <= KVM_MAX_HUGEPAGE_LEVEL; ++i) { linfo = lpage_info_slot(gfn, slot, i); + + disallow_count = linfo->disallow_lpage & KVM_LPAGE_COUNT_MAX; + WARN_ON(disallow_count + count < 0 || + disallow_count > KVM_LPAGE_COUNT_MAX - count); + linfo->disallow_lpage += count; - WARN_ON(linfo->disallow_lpage < 0); } } @@ -6986,3 +6991,130 @@ void kvm_mmu_pre_destroy_vm(struct kvm *kvm) if (kvm->arch.nx_huge_page_recovery_thread) kthread_stop(kvm->arch.nx_huge_page_recovery_thread); } + +static bool linfo_is_mixed(struct kvm_lpage_info *linfo) +{ + return linfo->disallow_lpage & KVM_LPAGE_PRIVATE_SHARED_MIXED; +} + +static void linfo_set_mixed(gfn_t gfn, struct kvm_memory_slot *slot, + int level, bool mixed) +{ + struct kvm_lpage_info *linfo = lpage_info_slot(gfn, slot, level); + + if (mixed) + linfo->disallow_lpage |= KVM_LPAGE_PRIVATE_SHARED_MIXED; + else + linfo->disallow_lpage &= ~KVM_LPAGE_PRIVATE_SHARED_MIXED; +} + +static bool is_expected_attr_entry(void *entry, unsigned long expected_attrs) +{ + bool expect_private = expected_attrs & KVM_MEMORY_ATTRIBUTE_PRIVATE; + + if (xa_to_value(entry) & KVM_MEMORY_ATTRIBUTE_PRIVATE) { + if (!expect_private) + return false; + } else if (expect_private) + return false; + + return true; +} + +static bool mem_attrs_mixed_2m(struct kvm *kvm, unsigned long attrs, + gfn_t start, gfn_t end) +{ + XA_STATE(xas, &kvm->mem_attr_array, start); + gfn_t gfn = start; + void *entry; + bool mixed = false; + + rcu_read_lock(); + entry = xas_load(&xas); + while (gfn < end) { + if (xas_retry(&xas, entry)) + continue; + + KVM_BUG_ON(gfn != xas.xa_index, kvm); + + if (!is_expected_attr_entry(entry, attrs)) { + mixed = true; + break; + } + + entry = xas_next(&xas); + gfn++; + } + + rcu_read_unlock(); + return mixed; +} + +static bool mem_attrs_mixed(struct kvm *kvm, struct kvm_memory_slot *slot, + int level, unsigned long attrs, + gfn_t start, gfn_t end) +{ + unsigned long gfn; + + if (level == PG_LEVEL_2M) + return mem_attrs_mixed_2m(kvm, attrs, start, end); + + for (gfn = start; gfn < end; gfn += KVM_PAGES_PER_HPAGE(level - 1)) + if (linfo_is_mixed(lpage_info_slot(gfn, slot, level - 1)) || + !is_expected_attr_entry(xa_load(&kvm->mem_attr_array, gfn), + attrs)) + return true; + return false; +} + +static void kvm_update_lpage_private_shared_mixed(struct kvm *kvm, + struct kvm_memory_slot *slot, + unsigned long attrs, + gfn_t start, gfn_t end) +{ + unsigned long pages, mask; + gfn_t gfn, gfn_end, first, last; + int level; + bool mixed; + + /* + * The sequence matters here: we set the higher level basing on the + * lower level's scanning result. + */ + for (level = PG_LEVEL_2M; level <= KVM_MAX_HUGEPAGE_LEVEL; level++) { + pages = KVM_PAGES_PER_HPAGE(level); + mask = ~(pages - 1); + first = start & mask; + last = (end - 1) & mask; + + /* + * We only need to scan the head and tail page, for middle pages + * we know they will not be mixed. + */ + gfn = max(first, slot->base_gfn); + gfn_end = min(first + pages, slot->base_gfn + slot->npages); + mixed = mem_attrs_mixed(kvm, slot, level, attrs, gfn, gfn_end); + linfo_set_mixed(gfn, slot, level, mixed); + + if (first == last) + return; + + for (gfn = first + pages; gfn < last; gfn += pages) + linfo_set_mixed(gfn, slot, level, false); + + gfn = last; + gfn_end = min(last + pages, slot->base_gfn + slot->npages); + mixed = mem_attrs_mixed(kvm, slot, level, attrs, gfn, gfn_end); + linfo_set_mixed(gfn, slot, level, mixed); + } +} + +void kvm_arch_set_memory_attributes(struct kvm *kvm, + struct kvm_memory_slot *slot, + unsigned long attrs, + gfn_t start, gfn_t end) +{ + if (kvm_slot_can_be_private(slot)) + kvm_update_lpage_private_shared_mixed(kvm, slot, attrs, + start, end); +} diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 9a07380f8d3c..5aefcff614d2 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -12362,6 +12362,8 @@ static int kvm_alloc_memslot_metadata(struct kvm *kvm, if ((slot->base_gfn + npages) & (KVM_PAGES_PER_HPAGE(level) - 1)) linfo[lpages - 1].disallow_lpage = 1; ugfn = slot->userspace_addr >> PAGE_SHIFT; + if (kvm_slot_can_be_private(slot)) + ugfn |= slot->restricted_offset >> PAGE_SHIFT; /* * If the gfn and userspace address are not aligned wrt each * other, disable large page support for this slot. diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 3331c0c92838..25099c94e770 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -592,6 +592,11 @@ struct kvm_memory_slot { struct restrictedmem_notifier notifier; }; +static inline bool kvm_slot_can_be_private(const struct kvm_memory_slot *slot) +{ + return slot && (slot->flags & KVM_MEM_PRIVATE); +} + static inline bool kvm_slot_dirty_track_enabled(const struct kvm_memory_slot *slot) { return slot->flags & KVM_MEM_LOG_DIRTY_PAGES; @@ -2316,4 +2321,18 @@ static inline void kvm_account_pgtable_pages(void *virt, int nr) /* Max number of entries allowed for each kvm dirty ring */ #define KVM_DIRTY_RING_MAX_ENTRIES 65536 +#ifdef __KVM_HAVE_ARCH_SET_MEMORY_ATTRIBUTES +void kvm_arch_set_memory_attributes(struct kvm *kvm, + struct kvm_memory_slot *slot, + unsigned long attrs, + gfn_t start, gfn_t end); +#else +static inline void kvm_arch_set_memory_attributes(struct kvm *kvm, + struct kvm_memory_slot *slot, + unsigned long attrs, + gfn_t start, gfn_t end) +{ +} +#endif /* __KVM_HAVE_ARCH_SET_MEMORY_ATTRIBUTES */ + #endif diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 4e1e1e113bf0..e107afea32f0 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2354,7 +2354,8 @@ static u64 kvm_supported_mem_attributes(struct kvm *kvm) return 0; } -static void kvm_unmap_mem_range(struct kvm *kvm, gfn_t start, gfn_t end) +static void kvm_unmap_mem_range(struct kvm *kvm, gfn_t start, gfn_t end, + unsigned long attrs) { struct kvm_gfn_range gfn_range; struct kvm_memory_slot *slot; @@ -2378,6 +2379,10 @@ static void kvm_unmap_mem_range(struct kvm *kvm, gfn_t start, gfn_t end) gfn_range.slot = slot; r |= kvm_unmap_gfn_range(kvm, &gfn_range); + + kvm_arch_set_memory_attributes(kvm, slot, attrs, + gfn_range.start, + gfn_range.end); } } @@ -2427,7 +2432,7 @@ static int kvm_vm_ioctl_set_mem_attributes(struct kvm *kvm, idx = srcu_read_lock(&kvm->srcu); KVM_MMU_LOCK(kvm); if (i > start) - kvm_unmap_mem_range(kvm, start, i); + kvm_unmap_mem_range(kvm, start, i, attrs->attributes); kvm_mmu_invalidate_end(kvm); KVM_MMU_UNLOCK(kvm); srcu_read_unlock(&kvm->srcu, idx);