[PATCH 5.5 246/367] x86/kvm: Introduce kvm_(un)map_gfn()

Greg Kroah-Hartman
2020-02-10T12:58:28Z

From: Boris Ostrovsky <boris.ostrovsky@oracle.com>

commit 1eff70a9abd46f175defafd29bc17ad456f398a7 upstream.

kvm_vcpu_(un)map operates on gfns from any current address space.
In certain cases we want to make sure we are not mapping SMRAM
and for that we can use kvm_(un)map_gfn() that we are introducing
in this patch.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
include/linux/kvm_host.h | 2 ++
virt/kvm/kvm_main.c | 29 ++++++++++++++++++++++++-----
2 files changed, 26 insertions(+), 5 deletions(-)

--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -775,8 +775,10 @@ struct kvm_memory_slot *kvm_vcpu_gfn_to_
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);
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);
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,
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1821,12 +1821,13 @@ struct page *gfn_to_page(struct kvm *kvm
}
EXPORT_SYMBOL_GPL(gfn_to_page);

-static int __kvm_map_gfn(struct kvm_memory_slot *slot, gfn_t gfn,
+static int __kvm_map_gfn(struct kvm_memslots *slots, gfn_t gfn,
struct kvm_host_map *map)
{
kvm_pfn_t pfn;
void *hva = NULL;
struct page *page = KVM_UNMAPPED_PAGE;
+ struct kvm_memory_slot *slot = __gfn_to_memslot(slots, gfn);

if (!map)
return -EINVAL;
@@ -1855,14 +1856,20 @@ static int __kvm_map_gfn(struct kvm_memo
return 0;
}

+int kvm_map_gfn(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map)
+{
+ return __kvm_map_gfn(kvm_memslots(vcpu->kvm), gfn, map);
+}
+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_gfn_to_memslot(vcpu, gfn), gfn, map);
+ return __kvm_map_gfn(kvm_vcpu_memslots(vcpu), gfn, map);
}
EXPORT_SYMBOL_GPL(kvm_vcpu_map);

-void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map,
- bool dirty)
+static void __kvm_unmap_gfn(struct kvm_memory_slot *memslot,
+ struct kvm_host_map *map, bool dirty)
{
if (!map)
return;
@@ -1878,7 +1885,7 @@ void kvm_vcpu_unmap(struct kvm_vcpu *vcp
#endif

if (dirty) {
- kvm_vcpu_mark_page_dirty(vcpu, map->gfn);
+ mark_page_dirty_in_slot(memslot, map->gfn);
kvm_release_pfn_dirty(map->pfn);
} else {
kvm_release_pfn_clean(map->pfn);
@@ -1887,6 +1894,18 @@ void kvm_vcpu_unmap(struct kvm_vcpu *vcp
map->hva = NULL;
map->page = NULL;
}
+
+int kvm_unmap_gfn(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty)
+{
+ __kvm_unmap_gfn(gfn_to_memslot(vcpu->kvm, map->gfn), map, dirty);
+ 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);
+}
EXPORT_SYMBOL_GPL(kvm_vcpu_unmap);

struct page *kvm_vcpu_gfn_to_page(struct kvm_vcpu *vcpu, gfn_t gfn)