KVM: nVMX: Sync unsync'd vmcs02 state to vmcs12 on migration

Even when we are outside the nested guest, some vmcs02 fields
may not be in sync vs vmcs12.  This is intentional, even across
nested VM-exit, because the sync can be delayed until the nested
hypervisor performs a VMCLEAR or a VMREAD/VMWRITE that affects those
rarely accessed fields.

However, during KVM_GET_NESTED_STATE, the vmcs12 has to be up to date to
be able to restore it.  To fix that, call copy_vmcs02_to_vmcs12_rare()
before the vmcs12 contents are copied to userspace.

Fixes: 7952d769c29ca ("KVM: nVMX: Sync rarely accessed guest fields only when needed")
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210114205449.8715-2-mlevitsk@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 0fbb46990dfce110aa23e62a84c343b4c408eabc..776688f9d101725a60561278d64c900885f07982 100644 (file)
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -6077,11 +6077,14 @@ static int vmx_get_nested_state(struct kvm_vcpu *vcpu,
        if (is_guest_mode(vcpu)) {
                sync_vmcs02_to_vmcs12(vcpu, vmcs12);
                sync_vmcs02_to_vmcs12_rare(vcpu, vmcs12);
-       } else if (!vmx->nested.need_vmcs12_to_shadow_sync) {
-               if (vmx->nested.hv_evmcs)
-                       copy_enlightened_to_vmcs12(vmx);
-               else if (enable_shadow_vmcs)
-                       copy_shadow_to_vmcs12(vmx);
+       } else  {
+               copy_vmcs02_to_vmcs12_rare(vcpu, get_vmcs12(vcpu));
+               if (!vmx->nested.need_vmcs12_to_shadow_sync) {
+                       if (vmx->nested.hv_evmcs)
+                               copy_enlightened_to_vmcs12(vmx);
+                       else if (enable_shadow_vmcs)
+                               copy_shadow_to_vmcs12(vmx);
+               }
        }
 
        BUILD_BUG_ON(sizeof(user_vmx_nested_state->vmcs12) < VMCS12_SIZE);