On 28/02/2024 3:41 pm, Sean Christopherson wrote:
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@xxxxxxxxxx>
---
arch/x86/kvm/mmu/mmu.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index bd342ebd0809..9206cfa58feb 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5866,7 +5866,8 @@ int noinline kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 err
error_code |= PFERR_PRIVATE_ACCESS;
r = RET_PF_INVALID;
- if (unlikely(error_code & PFERR_RSVD_MASK)) {
+ if (unlikely((error_code & PFERR_RSVD_MASK) &&
+ !WARN_ON_ONCE(error_code & PFERR_PRIVATE_ACCESS))) {
r = handle_mmio_page_fault(vcpu, cr2_or_gpa, direct);
if (r == RET_PF_EMULATE)
goto emulate;
It seems this will make KVM continue to call kvm_mmu_do_page_fault()
when such private+reserve error code actually happens (e.g., due to
bug), because @r is still RET_PF_INVALID in such case.
Is it better to just return error, e.g., -EINVAL, and give up?
