[PATCH v1 09/40] i386/tdx: Update tdx_fixed0/1 bits by tdx_caps.cpuid_config[]

Xiaoyao Li
2022-08-02T07:49:07Z

tdx_cpuid_lookup[].tdx_fixed0/1 is the QEMU maintained data which
reflects TDX restrictions regrading how some CPUID is 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 e3e9a424512e..d12b03fa05c9 100644
--- a/target/i386/kvm/tdx.c
+++ b/target/i386/kvm/tdx.c
@@ -369,6 +369,34 @@ static void get_tdx_capabilities(void)
tdx_caps = caps;
}

+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 = (TdxGuest *)object_dynamic_cast(OBJECT(ms->cgs),
@@ -378,6 +406,8 @@ int tdx_kvm_init(MachineState *ms, Error **errp)
get_tdx_capabilities();
}

+ update_tdx_cpuid_lookup_by_tdx_caps();
+
tdx_guest = tdx;

return 0;
--
2.27.0