[Devel] [PATCH 2/2] KVM: nVMX: Don't halt vcpu when L1 is injecting events to L2

[Jan Dakinevich]

From: Chao Gao <chao.gao at intel.com>

Although L2 is in halt state, it will be in the active state after
VM entry if the VM entry is vectoring according to SDM 26.6.2 Activity
State. Halting the vcpu here means the event won't be injected to L2
and this decision isn't reported to L1. Thus L0 drops an event that
should be injected to L2.

Cc: Liran Alon <liran.alon at oracle.com>
Reviewed-by: Liran Alon <liran.alon at oracle.com>
Signed-off-by: Chao Gao <chao.gao at intel.com>
Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>

https://jira.sw.ru/browse/PSBM-83005
(cherry picked from commit 135a06c3a515bbd17729eb04f4f26316d48363d7)
Signed-off-by: Jan Dakinevich <jan.dakinevich at virtuozzo.com>
---
 arch/x86/kvm/vmx.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 5ac9221..28728ab 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -10113,7 +10113,12 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
 
 	vmcs12->launch_state = 1;
 
-	if (vmcs12->guest_activity_state == GUEST_ACTIVITY_HLT)
+	/*
+	 * If we're entering a halted L2 vcpu and the L2 vcpu won't be woken
+	 * by event injection, halt vcpu.
+	 */
+	if ((vmcs12->guest_activity_state == GUEST_ACTIVITY_HLT) &&
+	    !(vmcs12->vm_entry_intr_info_field & INTR_INFO_VALID_MASK))
 		return kvm_vcpu_halt(vcpu);
 
 	vmx->nested.nested_run_pending = 1;
-- 
2.1.4