[PATCH 23/31] KVM: pfncache: Fail to refresh if it contains memory protections

[Paolo Bonzini <pbonzini@redhat.com>]

From: Nicolas Saenz Julienne <nsaenz@amazon.com>

Similar to how pfncache disallows caching gfns mapped within read-only
memory slots, gfns marked as read-only by memory attributes must
fail to initialize. Unsurprisingly, the same behaviour applies to gfns
mapped as non-accessible (NR/NW), while non-executable mappings are fine.

Signed-off-by: Nicolas Saenz Julienne <nsaenz@amazon.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 virt/kvm/pfncache.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c
index 46ffae69fe77..39935740136d 100644
--- a/virt/kvm/pfncache.c
+++ b/virt/kvm/pfncache.c
@@ -298,7 +298,18 @@ static int __kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned l
 		    gpc->gpa != gpa || kvm_is_error_hva(gpc->uhva)) {
 			gfn_t gfn = gpa_to_gfn(gpa);
 
+			/*
+			 * RW memory attributes are incompatible with GPC. The
+			 * RW protection check has to happen after storing the
+			 * generation number.
+			 */
 			gpc->attrs_generation = kvm_mem_attributes_generation(kvm);
+			if (kvm_range_has_rw_memory_protections(kvm, gfn, gfn + 1)) {
+				gpc->uhva = KVM_HVA_ERR_BAD;
+				ret = -EFAULT;
+				goto out;
+			}
+
 			gpc->gpa = gpa;
 			gpc->slots_generation = slots->generation;
 			gpc->memslot = __gfn_to_memslot(slots, gfn);
-- 
2.52.0