| Message ID | 20230824080408.2933205-6-stevensd@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: allow mapping non-refcounted pages | expand |
On 8/24/23 11:04, David Stevens wrote: > From: David Stevens <stevensd@chromium.org> > > Stop passing FOLL_GET to __kvm_follow_pfn. This allows the host to map > memory into the guest that is backed by un-refcounted struct pages - for > example, the tail pages of higher order non-compound pages allocated by > the amdgpu driver via ttm_pool_alloc_page. > > The bulk of this change is tracking the is_refcounted_page flag so that > non-refcounted pages don't trigger page_count() == 0 warnings. This is > done by storing the flag in an unused bit in the sptes. This only bit is > not available in PAE SPTEs, so FOLL_GET is only omitted for TDP on > x86-64. > > Signed-off-by: David Stevens <stevensd@chromium.org> > --- > arch/x86/kvm/mmu/mmu.c | 55 +++++++++++++++++++++++---------- > arch/x86/kvm/mmu/mmu_internal.h | 1 + > arch/x86/kvm/mmu/paging_tmpl.h | 8 +++-- > arch/x86/kvm/mmu/spte.c | 4 ++- > arch/x86/kvm/mmu/spte.h | 12 ++++++- > arch/x86/kvm/mmu/tdp_mmu.c | 22 +++++++------ > include/linux/kvm_host.h | 3 ++ > virt/kvm/kvm_main.c | 6 ++-- > 8 files changed, 79 insertions(+), 32 deletions(-) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index dabae67f198b..4f5d33e95c6e 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -553,12 +553,14 @@ static bool mmu_spte_update(u64 *sptep, u64 new_spte) > > if (is_accessed_spte(old_spte) && !is_accessed_spte(new_spte)) { > flush = true; > - kvm_set_pfn_accessed(spte_to_pfn(old_spte)); > + if (is_refcounted_page_pte(old_spte)) > + kvm_set_page_accessed(pfn_to_page(spte_to_pfn(old_spte))); > } > > if (is_dirty_spte(old_spte) && !is_dirty_spte(new_spte)) { > flush = true; > - kvm_set_pfn_dirty(spte_to_pfn(old_spte)); > + if (is_refcounted_page_pte(old_spte)) > + kvm_set_page_dirty(pfn_to_page(spte_to_pfn(old_spte))); > } > > return flush; > @@ -596,14 +598,18 @@ static u64 mmu_spte_clear_track_bits(struct kvm *kvm, u64 *sptep) > * before they are reclaimed. Sanity check that, if the pfn is backed > * by a refcounted page, the refcount is elevated. > */ > - page = kvm_pfn_to_refcounted_page(pfn); > - WARN_ON(page && !page_count(page)); > + if (is_refcounted_page_pte(old_spte)) { > + page = kvm_pfn_to_refcounted_page(pfn); > + WARN_ON(!page || !page_count(page)); > + } > > - if (is_accessed_spte(old_spte)) > - kvm_set_pfn_accessed(pfn); > + if (is_refcounted_page_pte(old_spte)) { > + if (is_accessed_spte(old_spte)) > + kvm_set_page_accessed(pfn_to_page(pfn)); > > - if (is_dirty_spte(old_spte)) > - kvm_set_pfn_dirty(pfn); > + if (is_dirty_spte(old_spte)) > + kvm_set_page_dirty(pfn_to_page(pfn)); > + } > > return old_spte; > } > @@ -639,8 +645,8 @@ static bool mmu_spte_age(u64 *sptep) > * Capture the dirty status of the page, so that it doesn't get > * lost when the SPTE is marked for access tracking. > */ > - if (is_writable_pte(spte)) > - kvm_set_pfn_dirty(spte_to_pfn(spte)); > + if (is_writable_pte(spte) && is_refcounted_page_pte(spte)) > + kvm_set_page_dirty(pfn_to_page(spte_to_pfn(spte))); > > spte = mark_spte_for_access_track(spte); > mmu_spte_update_no_track(sptep, spte); > @@ -1278,8 +1284,8 @@ static bool spte_wrprot_for_clear_dirty(u64 *sptep) > { > bool was_writable = test_and_clear_bit(PT_WRITABLE_SHIFT, > (unsigned long *)sptep); > - if (was_writable && !spte_ad_enabled(*sptep)) > - kvm_set_pfn_dirty(spte_to_pfn(*sptep)); > + if (was_writable && !spte_ad_enabled(*sptep) && is_refcounted_page_pte(*sptep)) > + kvm_set_page_dirty(pfn_to_page(spte_to_pfn(*sptep))); > > return was_writable; > } > @@ -2937,6 +2943,11 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot, > bool host_writable = !fault || fault->map_writable; > bool prefetch = !fault || fault->prefetch; > bool write_fault = fault && fault->write; > + /* > + * Prefetching uses gfn_to_page_many_atomic, which never gets > + * non-refcounted pages. > + */ > + bool is_refcounted = !fault || fault->is_refcounted_page; > > pgprintk("%s: spte %llx write_fault %d gfn %llx\n", __func__, > *sptep, write_fault, gfn); > @@ -2969,7 +2980,7 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot, > } > > wrprot = make_spte(vcpu, sp, slot, pte_access, gfn, pfn, *sptep, prefetch, > - true, host_writable, &spte); > + true, host_writable, is_refcounted, &spte); > > if (*sptep == spte) { > ret = RET_PF_SPURIOUS; > @@ -4296,11 +4307,19 @@ void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu, struct kvm_async_pf *work) > static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) > { > struct kvm_memory_slot *slot = fault->slot; > + /* > + * We only allow non-refcounted pages if we can track whether or not > + * pages are refcounted via an SPTE bit. This bit is not available > + * in PAE SPTEs, so pass FOLL_GET if we may have to deal with those. > + */ > + unsigned int get_flag = (tdp_enabled && IS_ENABLED(CONFIG_X86_64)) ? > + 0 : FOLL_GET; > struct kvm_follow_pfn foll = { > .slot = slot, > .gfn = fault->gfn, > - .flags = FOLL_GET | (fault->write ? FOLL_WRITE : 0), > + .flags = (fault->write ? FOLL_WRITE : 0) | get_flag, > .try_map_writable = true, > + .guarded_by_mmu_notifier = true, > }; > > /* > @@ -4317,6 +4336,7 @@ static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault > fault->slot = NULL; > fault->pfn = KVM_PFN_NOSLOT; > fault->map_writable = false; > + fault->is_refcounted_page = false; > return RET_PF_CONTINUE; > } > /* > @@ -4372,6 +4392,7 @@ static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault > success: > fault->hva = foll.hva; > fault->map_writable = foll.writable; > + fault->is_refcounted_page = foll.is_refcounted_page; > return RET_PF_CONTINUE; > } > > @@ -4456,8 +4477,9 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault > r = direct_map(vcpu, fault); > > out_unlock: > + if (fault->is_refcounted_page) > + kvm_set_page_accessed(pfn_to_page(fault->pfn)); > write_unlock(&vcpu->kvm->mmu_lock); > - kvm_release_pfn_clean(fault->pfn); Should we check FOLL_GET is actually omitted to skip the kvm_release_pfn_clean() ? > return r; > } > > @@ -4534,8 +4556,9 @@ static int kvm_tdp_mmu_page_fault(struct kvm_vcpu *vcpu, > r = kvm_tdp_mmu_map(vcpu, fault); > > out_unlock: > + if (fault->is_refcounted_page) > + kvm_set_page_accessed(pfn_to_page(fault->pfn)); > read_unlock(&vcpu->kvm->mmu_lock); > - kvm_release_pfn_clean(fault->pfn); > return r; > } > #endif > diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h > index d39af5639ce9..55790085884f 100644 > --- a/arch/x86/kvm/mmu/mmu_internal.h > +++ b/arch/x86/kvm/mmu/mmu_internal.h > @@ -240,6 +240,7 @@ struct kvm_page_fault { > kvm_pfn_t pfn; > hva_t hva; > bool map_writable; > + bool is_refcounted_page; > > /* > * Indicates the guest is trying to write a gfn that contains one or > diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h > index 0662e0278e70..4ffcebc0c3ce 100644 > --- a/arch/x86/kvm/mmu/paging_tmpl.h > +++ b/arch/x86/kvm/mmu/paging_tmpl.h > @@ -828,8 +828,9 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault > r = FNAME(fetch)(vcpu, fault, &walker); > > out_unlock: > + if (fault->is_refcounted_page) > + kvm_set_page_accessed(pfn_to_page(fault->pfn)); > write_unlock(&vcpu->kvm->mmu_lock); > - kvm_release_pfn_clean(fault->pfn); > return r; > } > > @@ -883,7 +884,7 @@ static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, > */ > static int FNAME(sync_spte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, int i) > { > - bool host_writable; > + bool host_writable, is_refcounted; > gpa_t first_pte_gpa; > u64 *sptep, spte; > struct kvm_memory_slot *slot; > @@ -940,10 +941,11 @@ static int FNAME(sync_spte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, int > sptep = &sp->spt[i]; > spte = *sptep; > host_writable = spte & shadow_host_writable_mask; > + is_refcounted = spte & SPTE_MMU_PAGE_REFCOUNTED; > slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); > make_spte(vcpu, sp, slot, pte_access, gfn, > spte_to_pfn(spte), spte, true, false, > - host_writable, &spte); > + host_writable, is_refcounted, &spte); > > return mmu_spte_update(sptep, spte); > } > diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c > index cf2c6426a6fc..5b13d9143d56 100644 > --- a/arch/x86/kvm/mmu/spte.c > +++ b/arch/x86/kvm/mmu/spte.c > @@ -138,7 +138,7 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, > const struct kvm_memory_slot *slot, > unsigned int pte_access, gfn_t gfn, kvm_pfn_t pfn, > u64 old_spte, bool prefetch, bool can_unsync, > - bool host_writable, u64 *new_spte) > + bool host_writable, bool is_refcounted, u64 *new_spte) > { > int level = sp->role.level; > u64 spte = SPTE_MMU_PRESENT_MASK; > @@ -188,6 +188,8 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, > > if (level > PG_LEVEL_4K) > spte |= PT_PAGE_SIZE_MASK; > + if (is_refcounted) > + spte |= SPTE_MMU_PAGE_REFCOUNTED; > > if (shadow_memtype_mask) > spte |= static_call(kvm_x86_get_mt_mask)(vcpu, gfn, > diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h > index 1279db2eab44..be93dd061ae3 100644 > --- a/arch/x86/kvm/mmu/spte.h > +++ b/arch/x86/kvm/mmu/spte.h > @@ -95,6 +95,11 @@ static_assert(!(EPT_SPTE_MMU_WRITABLE & SHADOW_ACC_TRACK_SAVED_MASK)); > /* Defined only to keep the above static asserts readable. */ > #undef SHADOW_ACC_TRACK_SAVED_MASK > > +/* > + * Indicates that the SPTE refers to a page with a valid refcount. > + */ > +#define SPTE_MMU_PAGE_REFCOUNTED BIT_ULL(59) > + > /* > * Due to limited space in PTEs, the MMIO generation is a 19 bit subset of > * the memslots generation and is derived as follows: > @@ -332,6 +337,11 @@ static inline bool is_dirty_spte(u64 spte) > return dirty_mask ? spte & dirty_mask : spte & PT_WRITABLE_MASK; > } > > +static inline bool is_refcounted_page_pte(u64 spte) > +{ > + return spte & SPTE_MMU_PAGE_REFCOUNTED; > +} > + > static inline u64 get_rsvd_bits(struct rsvd_bits_validate *rsvd_check, u64 pte, > int level) > { > @@ -462,7 +472,7 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, > const struct kvm_memory_slot *slot, > unsigned int pte_access, gfn_t gfn, kvm_pfn_t pfn, > u64 old_spte, bool prefetch, bool can_unsync, > - bool host_writable, u64 *new_spte); > + bool host_writable, bool is_refcounted, u64 *new_spte); > u64 make_huge_page_split_spte(struct kvm *kvm, u64 huge_spte, > union kvm_mmu_page_role role, int index); > u64 make_nonleaf_spte(u64 *child_pt, bool ad_disabled); > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > index 512163d52194..a9b1b14d2e26 100644 > --- a/arch/x86/kvm/mmu/tdp_mmu.c > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > @@ -474,6 +474,7 @@ 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 is_refcounted = is_refcounted_page_pte(old_spte); > > WARN_ON(level > PT64_ROOT_MAX_LEVEL); > WARN_ON(level < PG_LEVEL_4K); > @@ -538,9 +539,9 @@ static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, > if (is_leaf != was_leaf) > kvm_update_page_stats(kvm, level, is_leaf ? 1 : -1); > > - if (was_leaf && is_dirty_spte(old_spte) && > + if (was_leaf && is_dirty_spte(old_spte) && is_refcounted && > (!is_present || !is_dirty_spte(new_spte) || pfn_changed)) > - kvm_set_pfn_dirty(spte_to_pfn(old_spte)); > + kvm_set_page_dirty(pfn_to_page(spte_to_pfn(old_spte))); > > /* > * Recursively handle child PTs if the change removed a subtree from > @@ -552,9 +553,9 @@ static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, > (is_leaf || !is_present || WARN_ON_ONCE(pfn_changed))) > handle_removed_pt(kvm, spte_to_child_pt(old_spte, level), shared); > > - if (was_leaf && is_accessed_spte(old_spte) && > + if (was_leaf && is_accessed_spte(old_spte) && is_refcounted && > (!is_present || !is_accessed_spte(new_spte) || pfn_changed)) > - kvm_set_pfn_accessed(spte_to_pfn(old_spte)); > + kvm_set_page_accessed(pfn_to_page(spte_to_pfn(old_spte))); > } > > /* > @@ -988,8 +989,9 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu, > new_spte = make_mmio_spte(vcpu, iter->gfn, ACC_ALL); > else > wrprot = make_spte(vcpu, sp, fault->slot, ACC_ALL, iter->gfn, > - fault->pfn, iter->old_spte, fault->prefetch, true, > - fault->map_writable, &new_spte); > + fault->pfn, iter->old_spte, fault->prefetch, true, > + fault->map_writable, fault->is_refcounted_page, > + &new_spte); > > if (new_spte == iter->old_spte) > ret = RET_PF_SPURIOUS; > @@ -1205,8 +1207,9 @@ static bool age_gfn_range(struct kvm *kvm, struct tdp_iter *iter, > * Capture the dirty status of the page, so that it doesn't get > * lost when the SPTE is marked for access tracking. > */ > - if (is_writable_pte(iter->old_spte)) > - kvm_set_pfn_dirty(spte_to_pfn(iter->old_spte)); > + if (is_writable_pte(iter->old_spte) && > + is_refcounted_page_pte(iter->old_spte)) > + kvm_set_page_dirty(pfn_to_page(spte_to_pfn(iter->old_spte))); > > new_spte = mark_spte_for_access_track(iter->old_spte); > iter->old_spte = kvm_tdp_mmu_write_spte(iter->sptep, > @@ -1626,7 +1629,8 @@ static void clear_dirty_pt_masked(struct kvm *kvm, struct kvm_mmu_page *root, > trace_kvm_tdp_mmu_spte_changed(iter.as_id, iter.gfn, iter.level, > iter.old_spte, > iter.old_spte & ~dbit); > - kvm_set_pfn_dirty(spte_to_pfn(iter.old_spte)); > + if (is_refcounted_page_pte(iter.old_spte)) > + kvm_set_page_dirty(pfn_to_page(spte_to_pfn(iter.old_spte))); > } > > rcu_read_unlock(); > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 713fc2d91f95..292701339198 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -1157,6 +1157,9 @@ unsigned long gfn_to_hva_memslot_prot(struct kvm_memory_slot *slot, gfn_t gfn, > void kvm_release_page_clean(struct page *page); > void kvm_release_page_dirty(struct page *page); > > +void kvm_set_page_accessed(struct page *page); > +void kvm_set_page_dirty(struct page *page); > + > struct kvm_follow_pfn { > const struct kvm_memory_slot *slot; > gfn_t gfn; > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 963b96cd8ff9..fa1848c6c84f 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -2949,17 +2949,19 @@ static bool kvm_is_ad_tracked_page(struct page *page) > return !PageReserved(page); > } > > -static void kvm_set_page_dirty(struct page *page) > +void kvm_set_page_dirty(struct page *page) > { > if (kvm_is_ad_tracked_page(page)) > SetPageDirty(page); > } > +EXPORT_SYMBOL_GPL(kvm_set_page_dirty); > > -static void kvm_set_page_accessed(struct page *page) > +void kvm_set_page_accessed(struct page *page) > { > if (kvm_is_ad_tracked_page(page)) > mark_page_accessed(page); > } > +EXPORT_SYMBOL_GPL(kvm_set_page_accessed); > > void kvm_release_page_clean(struct page *page) > {
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index dabae67f198b..4f5d33e95c6e 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -553,12 +553,14 @@ static bool mmu_spte_update(u64 *sptep, u64 new_spte) if (is_accessed_spte(old_spte) && !is_accessed_spte(new_spte)) { flush = true; - kvm_set_pfn_accessed(spte_to_pfn(old_spte)); + if (is_refcounted_page_pte(old_spte)) + kvm_set_page_accessed(pfn_to_page(spte_to_pfn(old_spte))); } if (is_dirty_spte(old_spte) && !is_dirty_spte(new_spte)) { flush = true; - kvm_set_pfn_dirty(spte_to_pfn(old_spte)); + if (is_refcounted_page_pte(old_spte)) + kvm_set_page_dirty(pfn_to_page(spte_to_pfn(old_spte))); } return flush; @@ -596,14 +598,18 @@ static u64 mmu_spte_clear_track_bits(struct kvm *kvm, u64 *sptep) * before they are reclaimed. Sanity check that, if the pfn is backed * by a refcounted page, the refcount is elevated. */ - page = kvm_pfn_to_refcounted_page(pfn); - WARN_ON(page && !page_count(page)); + if (is_refcounted_page_pte(old_spte)) { + page = kvm_pfn_to_refcounted_page(pfn); + WARN_ON(!page || !page_count(page)); + } - if (is_accessed_spte(old_spte)) - kvm_set_pfn_accessed(pfn); + if (is_refcounted_page_pte(old_spte)) { + if (is_accessed_spte(old_spte)) + kvm_set_page_accessed(pfn_to_page(pfn)); - if (is_dirty_spte(old_spte)) - kvm_set_pfn_dirty(pfn); + if (is_dirty_spte(old_spte)) + kvm_set_page_dirty(pfn_to_page(pfn)); + } return old_spte; } @@ -639,8 +645,8 @@ static bool mmu_spte_age(u64 *sptep) * Capture the dirty status of the page, so that it doesn't get * lost when the SPTE is marked for access tracking. */ - if (is_writable_pte(spte)) - kvm_set_pfn_dirty(spte_to_pfn(spte)); + if (is_writable_pte(spte) && is_refcounted_page_pte(spte)) + kvm_set_page_dirty(pfn_to_page(spte_to_pfn(spte))); spte = mark_spte_for_access_track(spte); mmu_spte_update_no_track(sptep, spte); @@ -1278,8 +1284,8 @@ static bool spte_wrprot_for_clear_dirty(u64 *sptep) { bool was_writable = test_and_clear_bit(PT_WRITABLE_SHIFT, (unsigned long *)sptep); - if (was_writable && !spte_ad_enabled(*sptep)) - kvm_set_pfn_dirty(spte_to_pfn(*sptep)); + if (was_writable && !spte_ad_enabled(*sptep) && is_refcounted_page_pte(*sptep)) + kvm_set_page_dirty(pfn_to_page(spte_to_pfn(*sptep))); return was_writable; } @@ -2937,6 +2943,11 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot, bool host_writable = !fault || fault->map_writable; bool prefetch = !fault || fault->prefetch; bool write_fault = fault && fault->write; + /* + * Prefetching uses gfn_to_page_many_atomic, which never gets + * non-refcounted pages. + */ + bool is_refcounted = !fault || fault->is_refcounted_page; pgprintk("%s: spte %llx write_fault %d gfn %llx\n", __func__, *sptep, write_fault, gfn); @@ -2969,7 +2980,7 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot, } wrprot = make_spte(vcpu, sp, slot, pte_access, gfn, pfn, *sptep, prefetch, - true, host_writable, &spte); + true, host_writable, is_refcounted, &spte); if (*sptep == spte) { ret = RET_PF_SPURIOUS; @@ -4296,11 +4307,19 @@ void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu, struct kvm_async_pf *work) static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) { struct kvm_memory_slot *slot = fault->slot; + /* + * We only allow non-refcounted pages if we can track whether or not + * pages are refcounted via an SPTE bit. This bit is not available + * in PAE SPTEs, so pass FOLL_GET if we may have to deal with those. + */ + unsigned int get_flag = (tdp_enabled && IS_ENABLED(CONFIG_X86_64)) ? + 0 : FOLL_GET; struct kvm_follow_pfn foll = { .slot = slot, .gfn = fault->gfn, - .flags = FOLL_GET | (fault->write ? FOLL_WRITE : 0), + .flags = (fault->write ? FOLL_WRITE : 0) | get_flag, .try_map_writable = true, + .guarded_by_mmu_notifier = true, }; /* @@ -4317,6 +4336,7 @@ static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault fault->slot = NULL; fault->pfn = KVM_PFN_NOSLOT; fault->map_writable = false; + fault->is_refcounted_page = false; return RET_PF_CONTINUE; } /* @@ -4372,6 +4392,7 @@ static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault success: fault->hva = foll.hva; fault->map_writable = foll.writable; + fault->is_refcounted_page = foll.is_refcounted_page; return RET_PF_CONTINUE; } @@ -4456,8 +4477,9 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault r = direct_map(vcpu, fault); out_unlock: + if (fault->is_refcounted_page) + kvm_set_page_accessed(pfn_to_page(fault->pfn)); write_unlock(&vcpu->kvm->mmu_lock); - kvm_release_pfn_clean(fault->pfn); return r; } @@ -4534,8 +4556,9 @@ static int kvm_tdp_mmu_page_fault(struct kvm_vcpu *vcpu, r = kvm_tdp_mmu_map(vcpu, fault); out_unlock: + if (fault->is_refcounted_page) + kvm_set_page_accessed(pfn_to_page(fault->pfn)); read_unlock(&vcpu->kvm->mmu_lock); - kvm_release_pfn_clean(fault->pfn); return r; } #endif diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h index d39af5639ce9..55790085884f 100644 --- a/arch/x86/kvm/mmu/mmu_internal.h +++ b/arch/x86/kvm/mmu/mmu_internal.h @@ -240,6 +240,7 @@ struct kvm_page_fault { kvm_pfn_t pfn; hva_t hva; bool map_writable; + bool is_refcounted_page; /* * Indicates the guest is trying to write a gfn that contains one or diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h index 0662e0278e70..4ffcebc0c3ce 100644 --- a/arch/x86/kvm/mmu/paging_tmpl.h +++ b/arch/x86/kvm/mmu/paging_tmpl.h @@ -828,8 +828,9 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault r = FNAME(fetch)(vcpu, fault, &walker); out_unlock: + if (fault->is_refcounted_page) + kvm_set_page_accessed(pfn_to_page(fault->pfn)); write_unlock(&vcpu->kvm->mmu_lock); - kvm_release_pfn_clean(fault->pfn); return r; } @@ -883,7 +884,7 @@ static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, */ static int FNAME(sync_spte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, int i) { - bool host_writable; + bool host_writable, is_refcounted; gpa_t first_pte_gpa; u64 *sptep, spte; struct kvm_memory_slot *slot; @@ -940,10 +941,11 @@ static int FNAME(sync_spte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, int sptep = &sp->spt[i]; spte = *sptep; host_writable = spte & shadow_host_writable_mask; + is_refcounted = spte & SPTE_MMU_PAGE_REFCOUNTED; slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); make_spte(vcpu, sp, slot, pte_access, gfn, spte_to_pfn(spte), spte, true, false, - host_writable, &spte); + host_writable, is_refcounted, &spte); return mmu_spte_update(sptep, spte); } diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c index cf2c6426a6fc..5b13d9143d56 100644 --- a/arch/x86/kvm/mmu/spte.c +++ b/arch/x86/kvm/mmu/spte.c @@ -138,7 +138,7 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, const struct kvm_memory_slot *slot, unsigned int pte_access, gfn_t gfn, kvm_pfn_t pfn, u64 old_spte, bool prefetch, bool can_unsync, - bool host_writable, u64 *new_spte) + bool host_writable, bool is_refcounted, u64 *new_spte) { int level = sp->role.level; u64 spte = SPTE_MMU_PRESENT_MASK; @@ -188,6 +188,8 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, if (level > PG_LEVEL_4K) spte |= PT_PAGE_SIZE_MASK; + if (is_refcounted) + spte |= SPTE_MMU_PAGE_REFCOUNTED; if (shadow_memtype_mask) spte |= static_call(kvm_x86_get_mt_mask)(vcpu, gfn, diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h index 1279db2eab44..be93dd061ae3 100644 --- a/arch/x86/kvm/mmu/spte.h +++ b/arch/x86/kvm/mmu/spte.h @@ -95,6 +95,11 @@ static_assert(!(EPT_SPTE_MMU_WRITABLE & SHADOW_ACC_TRACK_SAVED_MASK)); /* Defined only to keep the above static asserts readable. */ #undef SHADOW_ACC_TRACK_SAVED_MASK +/* + * Indicates that the SPTE refers to a page with a valid refcount. + */ +#define SPTE_MMU_PAGE_REFCOUNTED BIT_ULL(59) + /* * Due to limited space in PTEs, the MMIO generation is a 19 bit subset of * the memslots generation and is derived as follows: @@ -332,6 +337,11 @@ static inline bool is_dirty_spte(u64 spte) return dirty_mask ? spte & dirty_mask : spte & PT_WRITABLE_MASK; } +static inline bool is_refcounted_page_pte(u64 spte) +{ + return spte & SPTE_MMU_PAGE_REFCOUNTED; +} + static inline u64 get_rsvd_bits(struct rsvd_bits_validate *rsvd_check, u64 pte, int level) { @@ -462,7 +472,7 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, const struct kvm_memory_slot *slot, unsigned int pte_access, gfn_t gfn, kvm_pfn_t pfn, u64 old_spte, bool prefetch, bool can_unsync, - bool host_writable, u64 *new_spte); + bool host_writable, bool is_refcounted, u64 *new_spte); u64 make_huge_page_split_spte(struct kvm *kvm, u64 huge_spte, union kvm_mmu_page_role role, int index); u64 make_nonleaf_spte(u64 *child_pt, bool ad_disabled); diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 512163d52194..a9b1b14d2e26 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -474,6 +474,7 @@ 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 is_refcounted = is_refcounted_page_pte(old_spte); WARN_ON(level > PT64_ROOT_MAX_LEVEL); WARN_ON(level < PG_LEVEL_4K); @@ -538,9 +539,9 @@ static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, if (is_leaf != was_leaf) kvm_update_page_stats(kvm, level, is_leaf ? 1 : -1); - if (was_leaf && is_dirty_spte(old_spte) && + if (was_leaf && is_dirty_spte(old_spte) && is_refcounted && (!is_present || !is_dirty_spte(new_spte) || pfn_changed)) - kvm_set_pfn_dirty(spte_to_pfn(old_spte)); + kvm_set_page_dirty(pfn_to_page(spte_to_pfn(old_spte))); /* * Recursively handle child PTs if the change removed a subtree from @@ -552,9 +553,9 @@ static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, (is_leaf || !is_present || WARN_ON_ONCE(pfn_changed))) handle_removed_pt(kvm, spte_to_child_pt(old_spte, level), shared); - if (was_leaf && is_accessed_spte(old_spte) && + if (was_leaf && is_accessed_spte(old_spte) && is_refcounted && (!is_present || !is_accessed_spte(new_spte) || pfn_changed)) - kvm_set_pfn_accessed(spte_to_pfn(old_spte)); + kvm_set_page_accessed(pfn_to_page(spte_to_pfn(old_spte))); } /* @@ -988,8 +989,9 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu, new_spte = make_mmio_spte(vcpu, iter->gfn, ACC_ALL); else wrprot = make_spte(vcpu, sp, fault->slot, ACC_ALL, iter->gfn, - fault->pfn, iter->old_spte, fault->prefetch, true, - fault->map_writable, &new_spte); + fault->pfn, iter->old_spte, fault->prefetch, true, + fault->map_writable, fault->is_refcounted_page, + &new_spte); if (new_spte == iter->old_spte) ret = RET_PF_SPURIOUS; @@ -1205,8 +1207,9 @@ static bool age_gfn_range(struct kvm *kvm, struct tdp_iter *iter, * Capture the dirty status of the page, so that it doesn't get * lost when the SPTE is marked for access tracking. */ - if (is_writable_pte(iter->old_spte)) - kvm_set_pfn_dirty(spte_to_pfn(iter->old_spte)); + if (is_writable_pte(iter->old_spte) && + is_refcounted_page_pte(iter->old_spte)) + kvm_set_page_dirty(pfn_to_page(spte_to_pfn(iter->old_spte))); new_spte = mark_spte_for_access_track(iter->old_spte); iter->old_spte = kvm_tdp_mmu_write_spte(iter->sptep, @@ -1626,7 +1629,8 @@ static void clear_dirty_pt_masked(struct kvm *kvm, struct kvm_mmu_page *root, trace_kvm_tdp_mmu_spte_changed(iter.as_id, iter.gfn, iter.level, iter.old_spte, iter.old_spte & ~dbit); - kvm_set_pfn_dirty(spte_to_pfn(iter.old_spte)); + if (is_refcounted_page_pte(iter.old_spte)) + kvm_set_page_dirty(pfn_to_page(spte_to_pfn(iter.old_spte))); } rcu_read_unlock(); diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 713fc2d91f95..292701339198 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1157,6 +1157,9 @@ unsigned long gfn_to_hva_memslot_prot(struct kvm_memory_slot *slot, gfn_t gfn, void kvm_release_page_clean(struct page *page); void kvm_release_page_dirty(struct page *page); +void kvm_set_page_accessed(struct page *page); +void kvm_set_page_dirty(struct page *page); + struct kvm_follow_pfn { const struct kvm_memory_slot *slot; gfn_t gfn; diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 963b96cd8ff9..fa1848c6c84f 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2949,17 +2949,19 @@ static bool kvm_is_ad_tracked_page(struct page *page) return !PageReserved(page); } -static void kvm_set_page_dirty(struct page *page) +void kvm_set_page_dirty(struct page *page) { if (kvm_is_ad_tracked_page(page)) SetPageDirty(page); } +EXPORT_SYMBOL_GPL(kvm_set_page_dirty); -static void kvm_set_page_accessed(struct page *page) +void kvm_set_page_accessed(struct page *page) { if (kvm_is_ad_tracked_page(page)) mark_page_accessed(page); } +EXPORT_SYMBOL_GPL(kvm_set_page_accessed); void kvm_release_page_clean(struct page *page) {