KVM: nVMX: Release eVMCS when enlightened VMENTRY was disabled

In theory, L1 can try to disable enlightened VMENTRY in VP assist page and
try to issue VMLAUNCH/VMRESUME. While nested_vmx_handle_enlightened_vmptrld()
properly handles this as 'EVMPTRLD_DISABLED', previously mapped eVMCS
remains mapped and thus all evmptr_is_valid() checks will still pass and
nested_vmx_run() will proceed when it shouldn't.

Release eVMCS immediately when we detect that enlightened vmentry was
disabled by L1.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210526132026.270394-4-vkuznets@redhat.com>
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 dbee5479103f42a347f81cef757cfac43f4243d0..8d814bf8448ee8a93adcfef0815e8aece3073a42 100644 (file)
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -1979,8 +1979,10 @@ static enum nested_evmptrld_status nested_vmx_handle_enlightened_vmptrld(
        if (likely(!vmx->nested.enlightened_vmcs_enabled))
                return EVMPTRLD_DISABLED;
 
-       if (!nested_enlightened_vmentry(vcpu, &evmcs_gpa))
+       if (!nested_enlightened_vmentry(vcpu, &evmcs_gpa)) {
+               nested_release_evmcs(vcpu);
                return EVMPTRLD_DISABLED;
+       }
 
        if (unlikely(evmcs_gpa != vmx->nested.hv_evmcs_vmptr)) {
                vmx->nested.current_vmptr = -1ull;