When nested state migration happens during L1's execution, it
is incorrect to modify eVMCS as it is L1 who 'owns' it at the moment.
At least genuine Hyper-V seems to not be very happy when 'clean fields'
data changes underneath it.
'Clean fields' data is used in KVM twice: by copy_enlightened_to_vmcs12()
and prepare_vmcs02_rare() so we can reset it from prepare_vmcs02() instead.
While at it, update a comment stating why exactly we need to reset
'hv_clean_fields' data from L0.
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
arch/x86/kvm/vmx/nested.c | 19 +++++++++++++------
1 file changed, 13 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 34b8e2471a5b..0f2e8eea2110 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -2060,14 +2060,10 @@ void nested_sync_vmcs12_to_shadow(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
- if (evmptr_is_valid(vmx->nested.hv_evmcs_vmptr)) {
+ if (evmptr_is_valid(vmx->nested.hv_evmcs_vmptr))
copy_vmcs12_to_enlightened(vmx);
- /* All fields are clean */
- vmx->nested.hv_evmcs->hv_clean_fields |=
- HV_VMX_ENLIGHTENED_CLEAN_FIELD_ALL;
- } else {
+ else
copy_vmcs12_to_shadow(vmx);
- }
vmx->nested.need_vmcs12_to_shadow_sync = false;
}
@@ -2607,6 +2603,17 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
kvm_rsp_write(vcpu, vmcs12->guest_rsp);
kvm_rip_write(vcpu, vmcs12->guest_rip);
+
+ /*
+ * It was observed that genuine Hyper-V running in L1 doesn't reset
+ * 'hv_clean_fields' by itself, it only sets the corresponding dirty
+ * bits when it changes a field in eVMCS. Mark all fields as clean
+ * here.
+ */
+ if (evmptr_is_valid(vmx->nested.hv_evmcs_vmptr))
+ vmx->nested.hv_evmcs->hv_clean_fields |=
+ HV_VMX_ENLIGHTENED_CLEAN_FIELD_ALL;
+
return 0;
}
--
2.31.1
