From: Boris Ostrovsky boris.ostrovsky@oracle.com
commit 917248144db5d7320655dbb41d3af0b8a0f3d589 upstream.
__kvm_map_gfn()'s call to gfn_to_pfn_memslot() is * relatively expensive * in certain cases (such as when done from atomic context) cannot be called
Stashing gfn-to-pfn mapping should help with both cases.
This is part of CVE-2019-3016.
Signed-off-by: Boris Ostrovsky boris.ostrovsky@oracle.com Reviewed-by: Joao Martins joao.m.martins@oracle.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Ben Hutchings ben.hutchings@codethink.co.uk Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/x86.c | 10 ++++ include/linux/kvm_host.h | 7 ++- include/linux/kvm_types.h | 9 ++- virt/kvm/kvm_main.c | 98 ++++++++++++++++++++++++++------- 5 files changed, 103 insertions(+), 22 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 5c99b9bfce045..ca9c7110b99dd 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -626,6 +626,7 @@ struct kvm_vcpu_arch { u64 last_steal; struct gfn_to_hva_cache stime; struct kvm_steal_time steal; + struct gfn_to_pfn_cache cache; } st;
u64 tsc_offset; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 1a6e1aa2fb297..6916f46909ab0 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8634,6 +8634,9 @@ static void fx_init(struct kvm_vcpu *vcpu) void kvm_arch_vcpu_free(struct kvm_vcpu *vcpu) { void *wbinvd_dirty_mask = vcpu->arch.wbinvd_dirty_mask; + struct gfn_to_pfn_cache *cache = &vcpu->arch.st.cache; + + kvm_release_pfn(cache->pfn, cache->dirty, cache);
kvmclock_reset(vcpu);
@@ -9298,11 +9301,18 @@ int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen) { + struct kvm_vcpu *vcpu; + int i; + /* * memslots->generation has been incremented. * mmio generation may have reached its maximum value. */ kvm_mmu_invalidate_mmio_sptes(kvm, gen); + + /* Force re-initialization of steal_time cache */ + kvm_for_each_vcpu(i, vcpu, kvm) + kvm_vcpu_kick(vcpu); }
int kvm_arch_prepare_memory_region(struct kvm *kvm, diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 303c1a6916cea..dabb60f907269 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -708,6 +708,7 @@ void kvm_set_pfn_dirty(kvm_pfn_t pfn); void kvm_set_pfn_accessed(kvm_pfn_t pfn); void kvm_get_pfn(kvm_pfn_t pfn);
+void kvm_release_pfn(kvm_pfn_t pfn, bool dirty, struct gfn_to_pfn_cache *cache); int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset, int len); int kvm_read_guest_atomic(struct kvm *kvm, gpa_t gpa, void *data, @@ -738,10 +739,12 @@ struct kvm_memory_slot *kvm_vcpu_gfn_to_memslot(struct kvm_vcpu *vcpu, gfn_t gfn kvm_pfn_t kvm_vcpu_gfn_to_pfn_atomic(struct kvm_vcpu *vcpu, gfn_t gfn); kvm_pfn_t kvm_vcpu_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn); int kvm_vcpu_map(struct kvm_vcpu *vcpu, gpa_t gpa, struct kvm_host_map *map); -int kvm_map_gfn(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map); +int kvm_map_gfn(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map, + struct gfn_to_pfn_cache *cache, bool atomic); struct page *kvm_vcpu_gfn_to_page(struct kvm_vcpu *vcpu, gfn_t gfn); void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty); -int kvm_unmap_gfn(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty); +int kvm_unmap_gfn(struct kvm_vcpu *vcpu, struct kvm_host_map *map, + struct gfn_to_pfn_cache *cache, bool dirty, bool atomic); unsigned long kvm_vcpu_gfn_to_hva(struct kvm_vcpu *vcpu, gfn_t gfn); unsigned long kvm_vcpu_gfn_to_hva_prot(struct kvm_vcpu *vcpu, gfn_t gfn, bool *writable); int kvm_vcpu_read_guest_page(struct kvm_vcpu *vcpu, gfn_t gfn, void *data, int offset, diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h index 8bf259dae9f6c..a38729c8296f4 100644 --- a/include/linux/kvm_types.h +++ b/include/linux/kvm_types.h @@ -32,7 +32,7 @@ struct kvm_memslots;
enum kvm_mr_change;
-#include <asm/types.h> +#include <linux/types.h>
/* * Address types: @@ -63,4 +63,11 @@ struct gfn_to_hva_cache { struct kvm_memory_slot *memslot; };
+struct gfn_to_pfn_cache { + u64 generation; + gfn_t gfn; + kvm_pfn_t pfn; + bool dirty; +}; + #endif /* __KVM_TYPES_H__ */ diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 8e29b2e0bf2eb..aca15bd1cc4cd 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1705,27 +1705,72 @@ struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn) } EXPORT_SYMBOL_GPL(gfn_to_page);
+void kvm_release_pfn(kvm_pfn_t pfn, bool dirty, struct gfn_to_pfn_cache *cache) +{ + if (pfn == 0) + return; + + if (cache) + cache->pfn = cache->gfn = 0; + + if (dirty) + kvm_release_pfn_dirty(pfn); + else + kvm_release_pfn_clean(pfn); +} + +static void kvm_cache_gfn_to_pfn(struct kvm_memory_slot *slot, gfn_t gfn, + struct gfn_to_pfn_cache *cache, u64 gen) +{ + kvm_release_pfn(cache->pfn, cache->dirty, cache); + + cache->pfn = gfn_to_pfn_memslot(slot, gfn); + cache->gfn = gfn; + cache->dirty = false; + cache->generation = gen; +} + static int __kvm_map_gfn(struct kvm_memslots *slots, gfn_t gfn, - struct kvm_host_map *map) + struct kvm_host_map *map, + struct gfn_to_pfn_cache *cache, + bool atomic) { kvm_pfn_t pfn; void *hva = NULL; struct page *page = KVM_UNMAPPED_PAGE; struct kvm_memory_slot *slot = __gfn_to_memslot(slots, gfn); + u64 gen = slots->generation;
if (!map) return -EINVAL;
- pfn = gfn_to_pfn_memslot(slot, gfn); + if (cache) { + if (!cache->pfn || cache->gfn != gfn || + cache->generation != gen) { + if (atomic) + return -EAGAIN; + kvm_cache_gfn_to_pfn(slot, gfn, cache, gen); + } + pfn = cache->pfn; + } else { + if (atomic) + return -EAGAIN; + pfn = gfn_to_pfn_memslot(slot, gfn); + } if (is_error_noslot_pfn(pfn)) return -EINVAL;
if (pfn_valid(pfn)) { page = pfn_to_page(pfn); - hva = kmap(page); + if (atomic) + hva = kmap_atomic(page); + else + hva = kmap(page); #ifdef CONFIG_HAS_IOMEM - } else { + } else if (!atomic) { hva = memremap(pfn_to_hpa(pfn), PAGE_SIZE, MEMREMAP_WB); + } else { + return -EINVAL; #endif }
@@ -1740,20 +1785,25 @@ static int __kvm_map_gfn(struct kvm_memslots *slots, gfn_t gfn, return 0; }
-int kvm_map_gfn(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map) +int kvm_map_gfn(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map, + struct gfn_to_pfn_cache *cache, bool atomic) { - return __kvm_map_gfn(kvm_memslots(vcpu->kvm), gfn, map); + return __kvm_map_gfn(kvm_memslots(vcpu->kvm), gfn, map, + cache, atomic); } EXPORT_SYMBOL_GPL(kvm_map_gfn);
int kvm_vcpu_map(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map) { - return __kvm_map_gfn(kvm_vcpu_memslots(vcpu), gfn, map); + return __kvm_map_gfn(kvm_vcpu_memslots(vcpu), gfn, map, + NULL, false); } EXPORT_SYMBOL_GPL(kvm_vcpu_map);
static void __kvm_unmap_gfn(struct kvm_memory_slot *memslot, - struct kvm_host_map *map, bool dirty) + struct kvm_host_map *map, + struct gfn_to_pfn_cache *cache, + bool dirty, bool atomic) { if (!map) return; @@ -1761,34 +1811,44 @@ static void __kvm_unmap_gfn(struct kvm_memory_slot *memslot, if (!map->hva) return;
- if (map->page != KVM_UNMAPPED_PAGE) - kunmap(map->page); + if (map->page != KVM_UNMAPPED_PAGE) { + if (atomic) + kunmap_atomic(map->hva); + else + kunmap(map->page); + } #ifdef CONFIG_HAS_IOMEM - else + else if (!atomic) memunmap(map->hva); + else + WARN_ONCE(1, "Unexpected unmapping in atomic context"); #endif
- if (dirty) { + if (dirty) mark_page_dirty_in_slot(memslot, map->gfn); - kvm_release_pfn_dirty(map->pfn); - } else { - kvm_release_pfn_clean(map->pfn); - } + + if (cache) + cache->dirty |= dirty; + else + kvm_release_pfn(map->pfn, dirty, NULL);
map->hva = NULL; map->page = NULL; }
-int kvm_unmap_gfn(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty) +int kvm_unmap_gfn(struct kvm_vcpu *vcpu, struct kvm_host_map *map, + struct gfn_to_pfn_cache *cache, bool dirty, bool atomic) { - __kvm_unmap_gfn(gfn_to_memslot(vcpu->kvm, map->gfn), map, dirty); + __kvm_unmap_gfn(gfn_to_memslot(vcpu->kvm, map->gfn), map, + cache, dirty, atomic); return 0; } EXPORT_SYMBOL_GPL(kvm_unmap_gfn);
void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty) { - __kvm_unmap_gfn(kvm_vcpu_gfn_to_memslot(vcpu, map->gfn), map, dirty); + __kvm_unmap_gfn(kvm_vcpu_gfn_to_memslot(vcpu, map->gfn), map, NULL, + dirty, false); } EXPORT_SYMBOL_GPL(kvm_vcpu_unmap);