linux-kernel - [PATCH 14/37] KVM: VMX: Prevent exit handler from running if emulating due to invalid state

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Date:	Fri, 27 Feb 2009 12:26:37 +0200
From:	Avi Kivity <avi@...hat.com>
To:	kvm@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH 14/37] KVM: VMX: Prevent exit handler from running if emulating due to invalid state

If we've just emulated an instruction, we won't have any valid exit
reason and associated information.

Fix by moving the clearing of the emulation_required flag to the exit handler.
This way the exit handler can notice that we've been emulating and abort
early.

Signed-off-by: Avi Kivity <avi@...hat.com>
---
 arch/x86/kvm/vmx.c |   11 ++++-------
 1 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index a6598cb..a309be6 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3130,7 +3130,6 @@ static int handle_nmi_window(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 static void handle_invalid_guest_state(struct kvm_vcpu *vcpu,
 				struct kvm_run *kvm_run)
 {
-	struct vcpu_vmx *vmx = to_vmx(vcpu);
 	int err;
 
 	preempt_enable();
@@ -3155,11 +3154,6 @@ static void handle_invalid_guest_state(struct kvm_vcpu *vcpu,
 
 	local_irq_disable();
 	preempt_disable();
-
-	/* Guest state should be valid now except if we need to
-	 * emulate an MMIO */
-	if (guest_state_valid(vcpu))
-		vmx->emulation_required = 0;
 }
 
 /*
@@ -3208,8 +3202,11 @@ static int kvm_handle_exit(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 
 	/* If we need to emulate an MMIO from handle_invalid_guest_state
 	 * we just return 0 */
-	if (vmx->emulation_required && emulate_invalid_guest_state)
+	if (vmx->emulation_required && emulate_invalid_guest_state) {
+		if (guest_state_valid(vcpu))
+			vmx->emulation_required = 0;
 		return 0;
+	}
 
 	/* Access CR3 don't cause VMExit in paging mode, so we need
 	 * to sync with guest real CR3. */
-- 
1.6.0.6

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