KVM: VMX: Inject #GP, not #UD, if SGX2 ENCLS leafs are unsupported

Per Intel's SDM, unsupported ENCLS leafs result in a #GP, not a #UD.
SGX1 is a special snowflake as the SGX1 flag is used by the CPU as a
"soft" disable, e.g. if software disables machine check reporting, i.e.
having SGX but not SGX1 is effectively "SGX completely unsupported" and
and thus #UDs.

Fixes: 9798adbc04cf ("KVM: VMX: Frame in ENCLS handler for SGX virtualization")
Cc: Binbin Wu <binbin.wu@linux.intel.com>
Cc: Kai Huang <kai.huang@intel.com>
Tested-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Link: https://lore.kernel.org/r/20230405234556.696927-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/kvm/vmx/sgx.c b/arch/x86/kvm/vmx/sgx.c
index 137088a..3e822e5 100644 (file)
--- a/arch/x86/kvm/vmx/sgx.c
+++ b/arch/x86/kvm/vmx/sgx.c
@@ -357,11 +357,12 @@ static int handle_encls_einit(struct kvm_vcpu *vcpu)
 
 static inline bool encls_leaf_enabled_in_guest(struct kvm_vcpu *vcpu, u32 leaf)
 {
-       if (!enable_sgx || !guest_cpuid_has(vcpu, X86_FEATURE_SGX))
-               return false;
-
+       /*
+        * ENCLS generates a #UD if SGX1 isn't supported, i.e. this point will
+        * be reached if and only if the SGX1 leafs are enabled.
+        */
        if (leaf >= ECREATE && leaf <= ETRACK)
-               return guest_cpuid_has(vcpu, X86_FEATURE_SGX1);
+               return true;
 
        if (leaf >= EAUG && leaf <= EMODT)
                return guest_cpuid_has(vcpu, X86_FEATURE_SGX2);
@@ -380,9 +381,11 @@ int handle_encls(struct kvm_vcpu *vcpu)
 {
        u32 leaf = (u32)kvm_rax_read(vcpu);
 
-       if (!encls_leaf_enabled_in_guest(vcpu, leaf)) {
+       if (!enable_sgx || !guest_cpuid_has(vcpu, X86_FEATURE_SGX) ||
+           !guest_cpuid_has(vcpu, X86_FEATURE_SGX1)) {
                kvm_queue_exception(vcpu, UD_VECTOR);
-       } else if (!sgx_enabled_in_guest_bios(vcpu) || !is_paging(vcpu)) {
+       } else if (!encls_leaf_enabled_in_guest(vcpu, leaf) ||
+                  !sgx_enabled_in_guest_bios(vcpu) || !is_paging(vcpu)) {
                kvm_inject_gp(vcpu, 0);
        } else {
                if (leaf == ECREATE)