Remove the WARN_ON in handle_ept_misconfig() as it is unnecessary
and causes false positives. Return the unmodified result of
kvm_mmu_page_fault() instead of converting a system error code to
KVM_EXIT_UNKNOWN so that userspace sees the error code of the
actual failure, not a generic "we don't know what went wrong".
* kvm_mmu_page_fault() will WARN if reserved bits are set in the
SPTEs, i.e. it covers the case where an EPT misconfig occurred
because of a KVM bug.
* The WARN_ON will fire on any system error code that is hit while
handling the fault, e.g. -ENOMEM from mmu_topup_memory_caches()
while handling a legitmate MMIO EPT misconfig or -EFAULT from
kvm_handle_bad_page() if the corresponding HVA is invalid. In
either case, userspace should receive the original error code
and firing a warning is incorrect behavior as KVM is operating
as designed.
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
---
arch/x86/kvm/vmx.c | 13 +------------
1 file changed, 1 insertion(+), 12 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 9bc05f5349c8..e328aef2a2f6 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -6875,7 +6875,6 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu)
static int handle_ept_misconfig(struct kvm_vcpu *vcpu)
{
- int ret;
gpa_t gpa;
/*
@@ -6903,17 +6902,7 @@ static int handle_ept_misconfig(struct kvm_vcpu *vcpu)
NULL, 0) == EMULATE_DONE;
}
- ret = kvm_mmu_page_fault(vcpu, gpa, PFERR_RSVD_MASK, NULL, 0);
- if (ret >= 0)
- return ret;
-
- /* It is the real ept misconfig */
- WARN_ON(1);
-
- vcpu->run->exit_reason = KVM_EXIT_UNKNOWN;
- vcpu->run->hw.hardware_exit_reason = EXIT_REASON_EPT_MISCONFIG;
-
- return 0;
+ return kvm_mmu_page_fault(vcpu, gpa, PFERR_RSVD_MASK, NULL, 0);
}
static int handle_nmi_window(struct kvm_vcpu *vcpu)
--
2.16.2
