[PATCH v3 21/70] i386/tdx: Update tdx_cpuid_lookup[].tdx_fixed0/1 by tdx_caps.cpuid_config[]

Xiaoyao Li
2023-11-15T07:17:53Z

tdx_cpuid_lookup[].tdx_fixed0/1 is QEMU maintained data which reflects
TDX restrictions regrading how some CPUIDs are virtualized by TDX.

It's retrieved from TDX spec. However, TDX may 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 <xiaoyao.li@intel.com>
---
target/i386/kvm/tdx.c | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)

diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
index eda6e695a884..7fa86858de58 100644
--- a/target/i386/kvm/tdx.c
+++ b/target/i386/kvm/tdx.c
@@ -374,6 +374,34 @@ 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;
+
+ /*
+ * Patch tdx_fixed0/1 by tdx_caps that what TDX module reports as
+ * configurable is not fixed.
+ */
+ 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);
+
+ entry->tdx_fixed0 &= ~config;
+ entry->tdx_fixed1 &= ~config;
+ }
+}
+
int tdx_kvm_init(MachineState *ms, Error **errp)
{
TdxGuest *tdx = TDX_GUEST(OBJECT(ms->cgs));
@@ -388,6 +416,8 @@ int tdx_kvm_init(MachineState *ms, Error **errp)
}
}

+ update_tdx_cpuid_lookup_by_tdx_caps();
+
tdx_guest = tdx;
return 0;
}
--
2.34.1