[PATCH 4/5] kvm/vmx: kick L2 guest to L1 by ready async_pf

[Roman Kagan <rkagan@virtuozzo.com>]

When async pagefault is resolved vCPU may be executing L2 guest.

In order to allow L1 take better scheduling decisions in such cases,
make L2 exit to L1 on a fake external interupt, without actually
injecting it (unless L2 has other reasons to vmexit).

This patch does that for x86/Intel.

Signed-off-by: Roman Kagan <rkagan@virtuozzo.com>
---
 arch/x86/kvm/vmx.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 5382b82..fc97489 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -10420,7 +10420,8 @@ static int vmx_check_nested_events(struct kvm_vcpu *vcpu, bool external_intr)
 		return 0;
 	}
 
-	if ((kvm_cpu_has_interrupt(vcpu) || external_intr) &&
+	if ((kvm_cpu_has_interrupt(vcpu) || external_intr ||
+	     kvm_async_pf_has_ready(vcpu)) &&
 	    nested_exit_on_intr(vcpu)) {
 		if (vmx->nested.nested_run_pending)
 			return -EBUSY;
@@ -10772,9 +10773,9 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
 	if ((exit_reason == EXIT_REASON_EXTERNAL_INTERRUPT)
 	    && nested_exit_intr_ack_set(vcpu)) {
 		int irq = kvm_cpu_get_interrupt(vcpu);
-		WARN_ON(irq < 0);
-		vmcs12->vm_exit_intr_info = irq |
-			INTR_INFO_VALID_MASK | INTR_TYPE_EXT_INTR;
+		if (irq >= 0)
+			vmcs12->vm_exit_intr_info = irq |
+				INTR_INFO_VALID_MASK | INTR_TYPE_EXT_INTR;
 	}
 
 	trace_kvm_nested_vmexit_inject(vmcs12->vm_exit_reason,
-- 
2.9.3