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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>
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@ -689,6 +689,7 @@ struct kvm_vcpu_arch {
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u64 last_steal;
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struct gfn_to_hva_cache stime;
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struct kvm_steal_time steal;
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struct gfn_to_pfn_cache cache;
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} st;
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u64 tsc_offset;
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@ -9088,6 +9088,9 @@ static void fx_init(struct kvm_vcpu *vcpu)
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void kvm_arch_vcpu_free(struct kvm_vcpu *vcpu)
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{
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void *wbinvd_dirty_mask = vcpu->arch.wbinvd_dirty_mask;
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struct gfn_to_pfn_cache *cache = &vcpu->arch.st.cache;
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kvm_release_pfn(cache->pfn, cache->dirty, cache);
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kvmclock_reset(vcpu);
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@ -9761,11 +9764,18 @@ out_free:
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void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen)
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{
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struct kvm_vcpu *vcpu;
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int i;
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/*
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* memslots->generation has been incremented.
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* mmio generation may have reached its maximum value.
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*/
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kvm_mmu_invalidate_mmio_sptes(kvm, gen);
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/* Force re-initialization of steal_time cache */
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kvm_for_each_vcpu(i, vcpu, kvm)
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kvm_vcpu_kick(vcpu);
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}
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int kvm_arch_prepare_memory_region(struct kvm *kvm,
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@ -723,6 +723,7 @@ void kvm_set_pfn_dirty(kvm_pfn_t pfn);
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void kvm_set_pfn_accessed(kvm_pfn_t pfn);
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void kvm_get_pfn(kvm_pfn_t pfn);
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void kvm_release_pfn(kvm_pfn_t pfn, bool dirty, struct gfn_to_pfn_cache *cache);
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int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset,
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int len);
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int kvm_read_guest_atomic(struct kvm *kvm, gpa_t gpa, void *data,
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@ -775,10 +776,12 @@ struct kvm_memory_slot *kvm_vcpu_gfn_to_memslot(struct kvm_vcpu *vcpu, gfn_t gfn
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kvm_pfn_t kvm_vcpu_gfn_to_pfn_atomic(struct kvm_vcpu *vcpu, gfn_t gfn);
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kvm_pfn_t kvm_vcpu_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn);
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int kvm_vcpu_map(struct kvm_vcpu *vcpu, gpa_t gpa, struct kvm_host_map *map);
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int kvm_map_gfn(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map);
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int kvm_map_gfn(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map,
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struct gfn_to_pfn_cache *cache, bool atomic);
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struct page *kvm_vcpu_gfn_to_page(struct kvm_vcpu *vcpu, gfn_t gfn);
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void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty);
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int kvm_unmap_gfn(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty);
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int kvm_unmap_gfn(struct kvm_vcpu *vcpu, struct kvm_host_map *map,
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struct gfn_to_pfn_cache *cache, bool dirty, bool atomic);
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unsigned long kvm_vcpu_gfn_to_hva(struct kvm_vcpu *vcpu, gfn_t gfn);
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unsigned long kvm_vcpu_gfn_to_hva_prot(struct kvm_vcpu *vcpu, gfn_t gfn, bool *writable);
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int kvm_vcpu_read_guest_page(struct kvm_vcpu *vcpu, gfn_t gfn, void *data, int offset,
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@ -18,7 +18,7 @@ struct kvm_memslots;
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enum kvm_mr_change;
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#include <asm/types.h>
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#include <linux/types.h>
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/*
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* Address types:
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@ -51,4 +51,11 @@ struct gfn_to_hva_cache {
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struct kvm_memory_slot *memslot;
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};
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struct gfn_to_pfn_cache {
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u64 generation;
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gfn_t gfn;
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kvm_pfn_t pfn;
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bool dirty;
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};
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#endif /* __KVM_TYPES_H__ */
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@ -1821,27 +1821,72 @@ struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
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}
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EXPORT_SYMBOL_GPL(gfn_to_page);
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void kvm_release_pfn(kvm_pfn_t pfn, bool dirty, struct gfn_to_pfn_cache *cache)
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{
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if (pfn == 0)
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return;
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if (cache)
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cache->pfn = cache->gfn = 0;
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if (dirty)
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kvm_release_pfn_dirty(pfn);
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else
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kvm_release_pfn_clean(pfn);
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}
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static void kvm_cache_gfn_to_pfn(struct kvm_memory_slot *slot, gfn_t gfn,
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struct gfn_to_pfn_cache *cache, u64 gen)
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{
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kvm_release_pfn(cache->pfn, cache->dirty, cache);
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cache->pfn = gfn_to_pfn_memslot(slot, gfn);
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cache->gfn = gfn;
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cache->dirty = false;
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cache->generation = gen;
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}
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static int __kvm_map_gfn(struct kvm_memslots *slots, gfn_t gfn,
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struct kvm_host_map *map)
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struct kvm_host_map *map,
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struct gfn_to_pfn_cache *cache,
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bool atomic)
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{
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kvm_pfn_t pfn;
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void *hva = NULL;
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struct page *page = KVM_UNMAPPED_PAGE;
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struct kvm_memory_slot *slot = __gfn_to_memslot(slots, gfn);
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u64 gen = slots->generation;
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if (!map)
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return -EINVAL;
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pfn = gfn_to_pfn_memslot(slot, gfn);
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if (cache) {
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if (!cache->pfn || cache->gfn != gfn ||
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cache->generation != gen) {
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if (atomic)
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return -EAGAIN;
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kvm_cache_gfn_to_pfn(slot, gfn, cache, gen);
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}
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pfn = cache->pfn;
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} else {
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if (atomic)
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return -EAGAIN;
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pfn = gfn_to_pfn_memslot(slot, gfn);
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}
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if (is_error_noslot_pfn(pfn))
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return -EINVAL;
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if (pfn_valid(pfn)) {
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page = pfn_to_page(pfn);
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hva = kmap(page);
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if (atomic)
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hva = kmap_atomic(page);
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else
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hva = kmap(page);
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#ifdef CONFIG_HAS_IOMEM
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} else {
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} else if (!atomic) {
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hva = memremap(pfn_to_hpa(pfn), PAGE_SIZE, MEMREMAP_WB);
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} else {
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return -EINVAL;
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#endif
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}
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@ -1856,20 +1901,25 @@ static int __kvm_map_gfn(struct kvm_memslots *slots, gfn_t gfn,
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return 0;
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}
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int kvm_map_gfn(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map)
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int kvm_map_gfn(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map,
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struct gfn_to_pfn_cache *cache, bool atomic)
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{
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return __kvm_map_gfn(kvm_memslots(vcpu->kvm), gfn, map);
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return __kvm_map_gfn(kvm_memslots(vcpu->kvm), gfn, map,
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cache, atomic);
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}
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EXPORT_SYMBOL_GPL(kvm_map_gfn);
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int kvm_vcpu_map(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map)
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{
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return __kvm_map_gfn(kvm_vcpu_memslots(vcpu), gfn, map);
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return __kvm_map_gfn(kvm_vcpu_memslots(vcpu), gfn, map,
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NULL, false);
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}
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EXPORT_SYMBOL_GPL(kvm_vcpu_map);
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static void __kvm_unmap_gfn(struct kvm_memory_slot *memslot,
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struct kvm_host_map *map, bool dirty)
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struct kvm_host_map *map,
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struct gfn_to_pfn_cache *cache,
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bool dirty, bool atomic)
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{
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if (!map)
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return;
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@ -1877,34 +1927,44 @@ static void __kvm_unmap_gfn(struct kvm_memory_slot *memslot,
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if (!map->hva)
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return;
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if (map->page != KVM_UNMAPPED_PAGE)
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kunmap(map->page);
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if (map->page != KVM_UNMAPPED_PAGE) {
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if (atomic)
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kunmap_atomic(map->hva);
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else
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kunmap(map->page);
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}
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#ifdef CONFIG_HAS_IOMEM
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else
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else if (!atomic)
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memunmap(map->hva);
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else
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WARN_ONCE(1, "Unexpected unmapping in atomic context");
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#endif
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if (dirty) {
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if (dirty)
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mark_page_dirty_in_slot(memslot, map->gfn);
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kvm_release_pfn_dirty(map->pfn);
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} else {
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kvm_release_pfn_clean(map->pfn);
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}
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if (cache)
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cache->dirty |= dirty;
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else
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kvm_release_pfn(map->pfn, dirty, NULL);
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map->hva = NULL;
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map->page = NULL;
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}
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int kvm_unmap_gfn(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty)
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int kvm_unmap_gfn(struct kvm_vcpu *vcpu, struct kvm_host_map *map,
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struct gfn_to_pfn_cache *cache, bool dirty, bool atomic)
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{
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__kvm_unmap_gfn(gfn_to_memslot(vcpu->kvm, map->gfn), map, dirty);
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__kvm_unmap_gfn(gfn_to_memslot(vcpu->kvm, map->gfn), map,
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cache, dirty, atomic);
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return 0;
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}
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EXPORT_SYMBOL_GPL(kvm_unmap_gfn);
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void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty)
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{
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__kvm_unmap_gfn(kvm_vcpu_gfn_to_memslot(vcpu, map->gfn), map, dirty);
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__kvm_unmap_gfn(kvm_vcpu_gfn_to_memslot(vcpu, map->gfn), map, NULL,
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dirty, false);
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}
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EXPORT_SYMBOL_GPL(kvm_vcpu_unmap);
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