linux-kernel - [PATCH 1/9] KVM: SVM: Notify nested hypervisor of lost event injections

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Date:	Fri, 9 Oct 2009 16:08:25 +0200
From:	Joerg Roedel <joerg.roedel@....com>
To:	Avi Kivity <avi@...hat.com>, Marcelo Tosatti <mtosatti@...hat.com>
CC:	Alexander Graf <agraf@...e.de>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org, Joerg Roedel <joerg.roedel@....com>
Subject: [PATCH 1/9] KVM: SVM: Notify nested hypervisor of lost event injections

From: Alexander Graf <agraf@...e.de>

If event_inj is valid on a #vmexit the host CPU would write
the contents to exit_int_info, so the hypervisor knows that
the event wasn't injected.

We don't do this in nested SVM by now which is a bug and
fixed by this patch.

Signed-off-by: Alexander Graf <agraf@...e.de>
Signed-off-by: Joerg Roedel <joerg.roedel@....com>
---
 arch/x86/kvm/svm.c |   16 ++++++++++++++++
 1 files changed, 16 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 279a2ae..e372854 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1615,6 +1615,22 @@ static int nested_svm_vmexit(struct vcpu_svm *svm)
 	nested_vmcb->control.exit_info_2       = vmcb->control.exit_info_2;
 	nested_vmcb->control.exit_int_info     = vmcb->control.exit_int_info;
 	nested_vmcb->control.exit_int_info_err = vmcb->control.exit_int_info_err;
+
+	/*
+	 * If we emulate a VMRUN/#VMEXIT in the same host #vmexit cycle we have
+	 * to make sure that we do not lose injected events. So check event_inj
+	 * here and copy it to exit_int_info if it is valid.
+	 * Exit_int_info and event_inj can't be both valid because the case
+	 * below only happens on a VMRUN instruction intercept which has
+	 * no valid exit_int_info set.
+	 */
+	if (vmcb->control.event_inj & SVM_EVTINJ_VALID) {
+		struct vmcb_control_area *nc = &nested_vmcb->control;
+
+		nc->exit_int_info     = vmcb->control.event_inj;
+		nc->exit_int_info_err = vmcb->control.event_inj_err;
+	}
+
 	nested_vmcb->control.tlb_ctl           = 0;
 	nested_vmcb->control.event_inj         = 0;
 	nested_vmcb->control.event_inj_err     = 0;
-- 
1.6.4.3


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