[v4,4/6] KVM: nVMX: Fix conditions for interrupt injection

Commit Message

Jan Kiszka April 14, 2013, 10:12 a.m. UTC

From: Jan Kiszka <[e-mail]>

If we are entering guest mode, we do not want L0 to interrupt this
vmentry with all its side effects on the vmcs. Therefore, injection
shall be disallowed during L1->L2 transitions, as in the previous
version. However, this check is conceptually independent of
nested_exit_on_intr, so decouple it.

If L1 traps external interrupts, we can kick the guest from L2 to L1,
also just like the previous code worked. But we no longer need to
consider L1's idt_vectoring_info_field. It will always be empty at this
point. Instead, if L2 has pending events, those are now found in the
architectural queues and will, thus, prevent vmx_interrupt_allowed from
being called at all.

Signed-off-by: Jan Kiszka <[e-mail]>
---
 arch/x86/kvm/vmx.c |   20 ++++++++++++--------
 1 files changed, 12 insertions(+), 8 deletions(-)

Patch

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 24680a9..56e7519 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -4325,16 +4325,20 @@  static int vmx_nmi_allowed(struct kvm_vcpu *vcpu)
 
 static int vmx_interrupt_allowed(struct kvm_vcpu *vcpu)
 {
-	if (is_guest_mode(vcpu) && nested_exit_on_intr(vcpu)) {
+	if (is_guest_mode(vcpu)) {
 		struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
-		if (to_vmx(vcpu)->nested.nested_run_pending ||
-		    (vmcs12->idt_vectoring_info_field &
-		     VECTORING_INFO_VALID_MASK))
+
+		if (to_vmx(vcpu)->nested.nested_run_pending)
 			return 0;
-		nested_vmx_vmexit(vcpu);
-		vmcs12->vm_exit_reason = EXIT_REASON_EXTERNAL_INTERRUPT;
-		vmcs12->vm_exit_intr_info = 0;
-		/* fall through to normal code, but now in L1, not L2 */
+		if (nested_exit_on_intr(vcpu)) {
+			nested_vmx_vmexit(vcpu);
+			vmcs12->vm_exit_reason =
+				EXIT_REASON_EXTERNAL_INTERRUPT;
+			vmcs12->vm_exit_intr_info = 0;
+			/*
+			 * fall through to normal code, but now in L1, not L2
+			 */
+		}
 	}
 
 	return (vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_IF) &&