[PATCH 5.10 044/142] KVM: nVMX: Sync unsyncd vmcs02 state to vmcs12 on migration

Greg Kroah-Hartman
2021-02-02T19:58:45Z

From: Maxim Levitsky <mlevitsk@redhat.com>

commit d51e1d3f6b4236e0352407d8a63f5c5f71ce193d upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/kvm/vmx/nested.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)

--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -6070,11 +6070,14 @@ static int vmx_get_nested_state(struct k
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);