[PATCH v4 13/33] i386: kvm: Add support for exposing PROVISIONKEY to guest

[Yang Zhong <yang.zhong@intel.com>]

From: Sean Christopherson <sean.j.christopherson@intel.com>

If the guest want to fully use SGX, the guest needs to be able to
access provisioning key. Add a new KVM_CAP_SGX_ATTRIBUTE to KVM to
support provisioning key to KVM guests.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Yang Zhong <yang.zhong@intel.com>
---
 target/i386/cpu.c          |  5 ++++-
 target/i386/kvm/kvm.c      | 29 +++++++++++++++++++++++++++++
 target/i386/kvm/kvm_i386.h |  2 ++
 3 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 8adfe80312..6ddeba7461 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -5509,7 +5509,10 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
             *ecx |= XSTATE_FP_MASK | XSTATE_SSE_MASK;
 
             /* Access to PROVISIONKEY requires additional credentials. */
-            *eax &= ~(1U << 4);
+            if ((*eax & (1U << 4)) &&
+                !kvm_enable_sgx_provisioning(cs->kvm_state)) {
+                *eax &= ~(1U << 4);
+            }
         }
 #endif
         break;
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 8d017fb5a6..05a1c370c3 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -4633,6 +4633,35 @@ void kvm_arch_update_guest_debug(CPUState *cpu, struct kvm_guest_debug *dbg)
     }
 }
 
+static bool has_sgx_provisioning;
+
+static bool __kvm_enable_sgx_provisioning(KVMState *s)
+{
+    int fd, ret;
+
+    if (!kvm_vm_check_extension(s, KVM_CAP_SGX_ATTRIBUTE)) {
+        return false;
+    }
+
+    fd = qemu_open_old("/dev/sgx_provision", O_RDONLY);
+    if (fd < 0) {
+        return false;
+    }
+
+    ret = kvm_vm_enable_cap(s, KVM_CAP_SGX_ATTRIBUTE, 0, fd);
+    if (ret) {
+        error_report("Could not enable SGX PROVISIONKEY: %s", strerror(-ret));
+        exit(1);
+    }
+    close(fd);
+    return true;
+}
+
+bool kvm_enable_sgx_provisioning(KVMState *s)
+{
+    return MEMORIZE(__kvm_enable_sgx_provisioning(s), has_sgx_provisioning);
+}
+
 static bool host_supports_vmx(void)
 {
     uint32_t ecx, unused;
diff --git a/target/i386/kvm/kvm_i386.h b/target/i386/kvm/kvm_i386.h
index 54667b35f0..a978509d50 100644
--- a/target/i386/kvm/kvm_i386.h
+++ b/target/i386/kvm/kvm_i386.h
@@ -51,4 +51,6 @@ bool kvm_hyperv_expand_features(X86CPU *cpu, Error **errp);
 
 uint64_t kvm_swizzle_msi_ext_dest_id(uint64_t address);
 
+bool kvm_enable_sgx_provisioning(KVMState *s);
+
 #endif