KVM: nVMX: allow setting the VMFUNC controls MSR

Allow userspace to set a custom value for the VMFUNC controls MSR, as long
as the capabilities it advertises do not exceed those of the host.

Fixes: 27c42a1bb ("KVM: nVMX: Enable VMFUNC for the L1 hypervisor", 2017-08-03)
Reviewed-by: Liran Alon <liran.alon@oracle.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 c4e29ef..163d226 100644 (file)
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -1234,6 +1234,11 @@ int vmx_set_vmx_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
        case MSR_IA32_VMX_VMCS_ENUM:
                vmx->nested.msrs.vmcs_enum = data;
                return 0;
+       case MSR_IA32_VMX_VMFUNC:
+               if (data & ~vmx->nested.msrs.vmfunc_controls)
+                       return -EINVAL;
+               vmx->nested.msrs.vmfunc_controls = data;
+               return 0;
        default:
                /*
                 * The rest of the VMX capability MSRs do not support restore.