From c75d0edc8e83541272c8c0177c4da153f22094e4 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Thu, 29 Mar 2018 14:48:31 -0700 Subject: [PATCH] KVM: VMX: remove bogus WARN_ON in handle_ept_misconfig 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 Signed-off-by: Paolo Bonzini --- 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 b2f8a700aeef..39a83a66a282 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -7078,7 +7078,6 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu) static int handle_ept_misconfig(struct kvm_vcpu *vcpu) { - int ret; gpa_t gpa; /* @@ -7106,17 +7105,7 @@ 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) -- GitLab