[PATCH] kvm: nVMX: Fetch VM_INSTRUCTION_ERROR from vmcs02 on vmx->fail

[PATCH] kvm: nVMX: Fetch VM_INSTRUCTION_ERROR from vmcs02 on vmx->fail

[Jim Mattson]

When forwarding a hardware VM-entry failure to L1, fetch the
VM_INSTRUCTION_ERROR field from vmcs02 before loading vmcs01.

(Note that there is an implicit assumption that the VM-entry failure was
on the first VM-entry to vmcs02 after nested_vmx_run; otherwise, L1 is
going to be very confused.)

Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Peter Feiner <pfeiner@google.com>
---
 arch/x86/kvm/vmx.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 5cede40..2ce8585 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -10714,6 +10714,7 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 	struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
+	u32 vm_inst_error = 0;
 
 	/* trying to cancel vmlaunch/vmresume is a bug */
 	WARN_ON_ONCE(vmx->nested.nested_run_pending);
@@ -10726,6 +10727,9 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
 				 vmcs12->vm_exit_msr_store_count))
 		nested_vmx_abort(vcpu, VMX_ABORT_SAVE_GUEST_MSR_FAIL);
 
+	if (unlikely(vmx->fail))
+		vm_inst_error = vmcs_read32(VM_INSTRUCTION_ERROR);
+
 	vmx_load_vmcs01(vcpu);
 
 	if ((exit_reason == EXIT_REASON_EXTERNAL_INTERRUPT)
@@ -10802,7 +10806,7 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
 	 */
 	if (unlikely(vmx->fail)) {
 		vmx->fail = 0;
-		nested_vmx_failValid(vcpu, vmcs_read32(VM_INSTRUCTION_ERROR));
+		nested_vmx_failValid(vcpu, vm_inst_error);
 	} else
 		nested_vmx_succeed(vcpu);
 	if (enable_shadow_vmcs)
-- 
2.8.0.rc3.226.g39d4020

Re: [PATCH] kvm: nVMX: Fetch VM_INSTRUCTION_ERROR from vmcs02 on vmx->fail

[Radim Krčmář]

2016-09-06 09:33-0700, Jim Mattson:
> When forwarding a hardware VM-entry failure to L1, fetch the
> VM_INSTRUCTION_ERROR field from vmcs02 before loading vmcs01.
> 
> (Note that there is an implicit assumption that the VM-entry failure was
> on the first VM-entry to vmcs02 after nested_vmx_run; otherwise, L1 is
> going to be very confused.)
> 
> Signed-off-by: Jim Mattson <jmattson@google.com>
> Reviewed-by: Peter Feiner <pfeiner@google.com>
> ---

Applied to kvm/queue, thanks.