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authorBoris Ostrovsky <boris.ostrovsky@oracle.com>2019-12-05 01:30:51 +0000
committerPaolo Bonzini <pbonzini@redhat.com>2020-01-30 18:45:55 +0100
commit917248144db5d7320655dbb41d3af0b8a0f3d589 (patch)
tree4c865f9aeb61137847ce9d283bc33febded17714 /virt
parent1eff70a9abd46f175defafd29bc17ad456f398a7 (diff)
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x86/kvm: Cache gfn to pfn translation
__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> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/kvm_main.c98
1 files changed, 79 insertions, 19 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 9ef58a233a7c..67eb302a7240 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1821,27 +1821,72 @@ 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
}
@@ -1856,20 +1901,25 @@ 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;
@@ -1877,34 +1927,44 @@ 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);