KVM: x86/mmu: WARN and skip MMIO cache on private, reserved page faults

WARN and skip the emulated MMIO fastpath if a private, reserved page fault
is encountered, as private+reserved should be an impossible combination
(KVM should never create an MMIO SPTE for a private access).

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20240228024147.41573-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 4bb121b5f58e45aa0607cfc13c48b70110b6cdc2..9560fca3a6cf621f9b43831cedfd7f4075d45834 100644 (file)
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5818,6 +5818,9 @@ int noinline kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 err
 
        r = RET_PF_INVALID;
        if (unlikely(error_code & PFERR_RSVD_MASK)) {
+               if (WARN_ON_ONCE(error_code & PFERR_PRIVATE_ACCESS))
+                       return -EFAULT;
+
                r = handle_mmio_page_fault(vcpu, cr2_or_gpa, direct);
                if (r == RET_PF_EMULATE)
                        goto emulate;