[v4,19/66] i386/tdx: Update tdx_cpuid_lookup[].tdx_fixed0/1 by tdx_caps.cpuid_config[]

Commit Message

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

tdx_cpuid_lookup[].tdx_fixed0/1 is QEMU maintained data which reflects
TDX restrictions regrading what bits are fixed by TDX module.

It's retrieved from TDX spec and static. However, TDX may evolve and
change some fixed fields to configurable in the future. Update
tdx_cpuid.lookup[].tdx_fixed0/1 fields by removing the bits that
reported from TDX module as configurable. This can adapt with the
updated TDX (module) automatically.

Signed-off-by: Xiaoyao Li <[e-mail]>
---
 target/i386/kvm/tdx.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

Patch

diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
index 2703e97f991d..5dfea0378f26 100644
--- a/target/i386/kvm/tdx.c
+++ b/target/i386/kvm/tdx.c
@@ -377,6 +377,38 @@  static int get_tdx_capabilities(Error **errp)
     return 0;
 }
 
+static void update_tdx_cpuid_lookup_by_tdx_caps(void)
+{
+    KvmTdxCpuidLookup *entry;
+    FeatureWordInfo *fi;
+    uint32_t config;
+    FeatureWord w;
+
+    for (w = 0; w < FEATURE_WORDS; w++) {
+        fi = &feature_word_info[w];
+        entry = &tdx_cpuid_lookup[w];
+
+        if (fi->type != CPUID_FEATURE_WORD) {
+            continue;
+        }
+
+        config = tdx_cap_cpuid_config(fi->cpuid.eax,
+                                      fi->cpuid.needs_ecx ? fi->cpuid.ecx : ~0u,
+                                      fi->cpuid.reg);
+
+        if (!config) {
+            continue;
+        }
+
+        /*
+         * Remove the configurable bits from tdx_fixed0/1 in case QEMU
+         * maintained fixed0/1 values is outdated to TDX module.
+         */
+        entry->tdx_fixed0 &= ~config;
+        entry->tdx_fixed1 &= ~config;
+    }
+}
+
 int tdx_kvm_init(MachineState *ms, Error **errp)
 {
     TdxGuest *tdx = TDX_GUEST(OBJECT(ms->cgs));
@@ -391,6 +423,8 @@  int tdx_kvm_init(MachineState *ms, Error **errp)
         }
     }
 
+    update_tdx_cpuid_lookup_by_tdx_caps();
+
     tdx_guest = tdx;
     return 0;
 }