[v4,28/66] i386/tdx: Validate TD attributes

Commit Message

Xiaoyao Li Jan. 25, 2024, 3:22 a.m. UTC

Validate TD attributes with tdx_caps that fixed-0 bits must be zero and
fixed-1 bits must be set.

Besides, sanity check the attribute bits that have not been supported by
QEMU yet. e.g., debug bit, it will be allowed in the future when debug
TD support lands in QEMU.

Signed-off-by: Xiaoyao Li <[e-mail]>
Acked-by: Gerd Hoffmann <[e-mail]>

---
Changes in v3:
- using error_setg() for error report; (Daniel)
---
 target/i386/kvm/tdx.c | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

Patch

diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
index 1cb38b5d6221..8c2bf512397e 100644
--- a/target/i386/kvm/tdx.c
+++ b/target/i386/kvm/tdx.c
@@ -32,6 +32,7 @@ 
                                      (1U << KVM_FEATURE_PV_SCHED_YIELD) | \
                                      (1U << KVM_FEATURE_MSI_EXT_DEST_ID))
 
+#define TDX_TD_ATTRIBUTES_DEBUG             BIT_ULL(0)
 #define TDX_TD_ATTRIBUTES_SEPT_VE_DISABLE   BIT_ULL(28)
 #define TDX_TD_ATTRIBUTES_PKS               BIT_ULL(30)
 #define TDX_TD_ATTRIBUTES_PERFMON           BIT_ULL(63)
@@ -478,13 +479,34 @@  int tdx_kvm_init(MachineState *ms, Error **errp)
     return 0;
 }
 
-static void setup_td_guest_attributes(X86CPU *x86cpu)
+static int tdx_validate_attributes(TdxGuest *tdx, Error **errp)
+{
+    if (((tdx->attributes & tdx_caps->attrs_fixed0) | tdx_caps->attrs_fixed1) !=
+        tdx->attributes) {
+            error_setg(errp, "Invalid attributes 0x%lx for TDX VM "
+                       "(fixed0 0x%llx, fixed1 0x%llx)",
+                       tdx->attributes, tdx_caps->attrs_fixed0,
+                       tdx_caps->attrs_fixed1);
+            return -1;
+    }
+
+    if (tdx->attributes & TDX_TD_ATTRIBUTES_DEBUG) {
+        error_setg(errp, "Current QEMU doesn't support attributes.debug[bit 0] for TDX VM");
+        return -1;
+    }
+
+    return 0;
+}
+
+static int setup_td_guest_attributes(X86CPU *x86cpu, Error **errp)
 {
     CPUX86State *env = &x86cpu->env;
 
     tdx_guest->attributes |= (env->features[FEAT_7_0_ECX] & CPUID_7_0_ECX_PKS) ?
                              TDX_TD_ATTRIBUTES_PKS : 0;
     tdx_guest->attributes |= x86cpu->enable_pmu ? TDX_TD_ATTRIBUTES_PERFMON : 0;
+
+    return tdx_validate_attributes(tdx_guest, errp);
 }
 
 int tdx_pre_create_vcpu(CPUState *cpu, Error **errp)
@@ -509,7 +531,10 @@  int tdx_pre_create_vcpu(CPUState *cpu, Error **errp)
         return r;
     }
 
-    setup_td_guest_attributes(x86cpu);
+    r = setup_td_guest_attributes(x86cpu, errp);
+    if (r) {
+        return r;
+    }
 
     init_vm->cpuid.nent = kvm_x86_arch_cpuid(env, init_vm->cpuid.entries, 0);