[PATCH 1/2] x86/kvm/hyper-v: nested_enable_evmcs() sets vmcs_version incorrectly

[Vitaly Kuznetsov]

Commit e2e871ab2f02 ("x86/kvm/hyper-v: Introduce nested_get_evmcs_version()
helper") broke EVMCS enablement: to set vmcs_version we now call
nested_get_evmcs_version() but this function checks
enlightened_vmcs_enabled flag which is not yet set so we end up returning
zero.

Fix the issue by re-arranging things in nested_enable_evmcs().

Fixes: e2e871ab2f02 ("x86/kvm/hyper-v: Introduce nested_get_evmcs_version() 
helper")
Signed-off-by: Vitaly Kuznetsov <vkuzn...@redhat.com>
---
 arch/x86/kvm/vmx/evmcs.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/vmx/evmcs.c b/arch/x86/kvm/vmx/evmcs.c
index 95bc2247478d..5466c6d85cf3 100644
--- a/arch/x86/kvm/vmx/evmcs.c
+++ b/arch/x86/kvm/vmx/evmcs.c
@@ -332,16 +332,17 @@ int nested_enable_evmcs(struct kvm_vcpu *vcpu,
                        uint16_t *vmcs_version)
 {
        struct vcpu_vmx *vmx = to_vmx(vcpu);
+       bool evmcs_already_enabled = vmx->nested.enlightened_vmcs_enabled;
+
+       vmx->nested.enlightened_vmcs_enabled = true;
 
        if (vmcs_version)
                *vmcs_version = nested_get_evmcs_version(vcpu);
 
        /* We don't support disabling the feature for simplicity. */
-       if (vmx->nested.enlightened_vmcs_enabled)
+       if (evmcs_already_enabled)
                return 0;
 
-       vmx->nested.enlightened_vmcs_enabled = true;
-
        vmx->nested.msrs.pinbased_ctls_high &= ~EVMCS1_UNSUPPORTED_PINCTRL;
        vmx->nested.msrs.entry_ctls_high &= ~EVMCS1_UNSUPPORTED_VMENTRY_CTRL;
        vmx->nested.msrs.exit_ctls_high &= ~EVMCS1_UNSUPPORTED_VMEXIT_CTRL;
-- 
2.20.1