[PATCH rfcv4 02/13] qemu: Check if INTEL Trust Domain Extention support is enabled

[Zhenzhong Duan <zhenzhong.duan@xxxxxxxxx>]

Implement TDX check in order to generate domain feature capability
correctly in case the availability of the feature changed.

For INTEL TDX the verification is:
 - checking if "/sys/module/kvm_intel/parameters/tdx" contains the
   value 'Y': meaning TDX is enabled in the host kernel.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@xxxxxxxxx>
Reviewed-by: Daniel P. Berrangé <berrange@xxxxxxxxxx>
---
 src/qemu/qemu_capabilities.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index 21f93c6774..7cccc28e80 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -5112,6 +5112,24 @@ virQEMUCapsKVMSupportsSecureGuestAMD(void)
 }
 
 
+/*
+ * Check whether INTEL Trust Domain Extention (x86) is enabled
+ */
+static bool
+virQEMUCapsKVMSupportsSecureGuestINTEL(void)
+{
+    g_autofree char *modValue = NULL;
+
+    if (virFileReadValueString(&modValue, "/sys/module/kvm_intel/parameters/tdx") < 0)
+        return false;
+
+    if (modValue[0] != 'Y')
+        return false;
+
+    return true;
+}
+
+
 /*
  * Check whether the secure guest functionality is enabled.
  * See the specific architecture function for details on the verifications made.
@@ -5125,7 +5143,8 @@ virQEMUCapsKVMSupportsSecureGuest(void)
         return virQEMUCapsKVMSupportsSecureGuestS390();
 
     if (ARCH_IS_X86(arch))
-        return virQEMUCapsKVMSupportsSecureGuestAMD();
+        return virQEMUCapsKVMSupportsSecureGuestAMD() ||
+               virQEMUCapsKVMSupportsSecureGuestINTEL();
 
     return false;
 }
-- 
2.34.1