[Utopic][SRU][PATCH 2/2] KVM: nVMX: Fix nested vmexit ack intr before load vmcs01

[Chris J Arges]

From: Wanpeng Li <wanpeng.li at linux.intel.com>

BugLink: http://bugs.launchpad.net/bugs/1448269

An external interrupt will cause a vmexit with reason "external interrupt"
when L2 is running.  L1 will pick up the interrupt through vmcs12 if
L1 set the ack interrupt bit.  Commit 77b0f5d (KVM: nVMX: Ack and write
vector info to intr_info if L1 asks us to) retrieves the interrupt that
belongs to L1 before vmcs01 is loaded.

This will lead to problems in the next patch, which would write to SVI
of vmcs02 instead of vmcs01 (SVI of vmcs02 doesn't make sense because
L2 runs without APICv).

Reviewed-by: Paolo Bonzini <pbonzini at redhat.com>
Tested-by: Liu, RongrongX <rongrongx.liu at intel.com>
Tested-by: Felipe Reyes <freyes at suse.com>
Fixes: 77b0f5d67ff2781f36831cba79674c3e97bd7acf
Cc: stable at vger.kernel.org
Signed-off-by: Wanpeng Li <wanpeng.li at linux.intel.com>
[Move tracepoint as well. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>

(cherry picked from commit f3380ca5d7edb5e31932998ab2e29dfdce39c5ed)
Signed-off-by: Chris J Arges <chris.j.arges at canonical.com>
---
 arch/x86/kvm/vmx.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 14a3d20..f6e09a8 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -8727,6 +8727,8 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
 	prepare_vmcs12(vcpu, vmcs12, exit_reason, exit_intr_info,
 		       exit_qualification);
 
+	vmx_load_vmcs01(vcpu);
+
 	if ((exit_reason == EXIT_REASON_EXTERNAL_INTERRUPT)
 	    && nested_exit_intr_ack_set(vcpu)) {
 		int irq = kvm_cpu_get_interrupt(vcpu);
@@ -8742,8 +8744,6 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
 				       vmcs12->vm_exit_intr_error_code,
 				       KVM_ISA_VMX);
 
-	vmx_load_vmcs01(vcpu);
-
 	vm_entry_controls_init(vmx, vmcs_read32(VM_ENTRY_CONTROLS));
 	vm_exit_controls_init(vmx, vmcs_read32(VM_EXIT_CONTROLS));
 	vmx_segment_cache_clear(vmx);
-- 
1.9.1