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-rw-r--r--virt/kvm/kvm_main.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 10bfc88a69f7..0f50960b0e3a 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1615,7 +1615,13 @@ static int check_memory_region_flags(struct kvm *kvm,
valid_flags &= ~KVM_MEM_LOG_DIRTY_PAGES;
#ifdef __KVM_HAVE_READONLY_MEM
- valid_flags |= KVM_MEM_READONLY;
+ /*
+ * GUEST_MEMFD is incompatible with read-only memslots, as writes to
+ * read-only memslots have emulated MMIO, not page fault, semantics,
+ * and KVM doesn't allow emulated MMIO for private memory.
+ */
+ if (!(mem->flags & KVM_MEM_GUEST_MEMFD))
+ valid_flags |= KVM_MEM_READONLY;
#endif
if (mem->flags & ~valid_flags)