KVM: x86: hyper-v: Honor HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED bit

Hyper-V partition must possess 'HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED'
privilege ('recommended' is rather a misnomer) to issue
HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST/SPACE hypercalls.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-26-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/hyperv.c

@@ -2112,6 +2112,12 @@ static bool hv_check_hypercall_access(struct kvm_vcpu_hv *hv_vcpu, u16 code)
 		 */
 		return !kvm_hv_is_syndbg_enabled(hv_vcpu->vcpu) ||
 			hv_vcpu->cpuid_cache.features_ebx & HV_DEBUGGING;
+	case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX:
+	case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX:
+	case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST:
+	case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE:
+		return hv_vcpu->cpuid_cache.enlightenments_eax &
+			HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED;
 	default:
 		break;
 	}