On Intel CPU, the value of CPUID_EXT2_SYSCALL depends on the mode of
the vcpu. It's 0 outside 64-bit mode and 1 in 64-bit mode.
The initial state of TDX vcpu is 32-bit protected mode. At the time of
calling KVM_TDX_GET_CPUID, vcpu hasn't started running so the value read
is 0.
In reality, 64-bit mode should always be supported. So mark
CPUID_EXT2_SYSCALL always supported to avoid false warning.
Signed-off-by: Xiaoyao Li <xiaoyao...@intel.com>
Reviewed-by: Zhao Liu <zhao1....@intel.com>
---
Changes in v9:
- Add commit message;
Changes in v7:
- fix CPUID_EXT2_SYSCALL by adding it to actual;
---
target/i386/kvm/tdx.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
index aa1bab644352..e9c680b74040 100644
--- a/target/i386/kvm/tdx.c
+++ b/target/i386/kvm/tdx.c
@@ -852,6 +852,19 @@ static int tdx_check_features(X86ConfidentialGuest *cg,
CPUState *cs)
continue;
}
+ /* Fixup for special cases */
+ switch (w) {
+ case FEAT_8000_0001_EDX:
+ /*
+ * Intel enumerates SYSCALL bit as 1 only when processor in 64-bit
+ * mode and before vcpu running it's not in 64-bit mode.
+ */
+ actual |= CPUID_EXT2_SYSCALL;
+ break;
+ default:
+ break;
+ }
+
requested = env->features[w];
unavailable = requested & ~actual;
mark_unavailable_features(cpu, w, unavailable, unav_prefix);
--
2.43.0
