linux-kernel - [PATCH 2/6] KVM: VMX: remove bogus check for invalid EPT violation

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Date:   Thu, 30 Mar 2017 11:55:28 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     david@...hat.com
Subject: [PATCH 2/6] KVM: VMX: remove bogus check for invalid EPT violation

handle_ept_violation is checking for "guest-linear-address invalid" +
"not a paging-structure walk".  However, _all_ EPT violations without
a valid guest linear address are paging structure walks, because those
EPT violations happen when loading the guest PDPTEs.

Therefore, the check can never be true, and even if it were, KVM doesn't
care about the guest linear address; it only uses the guest *physical*
address VMCS field.  So, remove the check altogether.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/vmx.c | 14 --------------
 1 file changed, 14 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 0e61b9226bf2..1c372600a962 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -6208,23 +6208,9 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu)
 	unsigned long exit_qualification;
 	gpa_t gpa;
 	u32 error_code;
-	int gla_validity;
 
 	exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
 
-	gla_validity = (exit_qualification >> 7) & 0x3;
-	if (gla_validity == 0x2) {
-		printk(KERN_ERR "EPT: Handling EPT violation failed!\n");
-		printk(KERN_ERR "EPT: GPA: 0x%lx, GVA: 0x%lx\n",
-			(long unsigned int)vmcs_read64(GUEST_PHYSICAL_ADDRESS),
-			vmcs_readl(GUEST_LINEAR_ADDRESS));
-		printk(KERN_ERR "EPT: Exit qualification is 0x%lx\n",
-			(long unsigned int)exit_qualification);
-		vcpu->run->exit_reason = KVM_EXIT_UNKNOWN;
-		vcpu->run->hw.hardware_exit_reason = EXIT_REASON_EPT_VIOLATION;
-		return 0;
-	}
-
 	/*
 	 * EPT violation happened while executing iret from NMI,
 	 * "blocked by NMI" bit has to be set before next VM entry.
-- 
1.8.3.1