Re: [PATCH v7 48/52] i386/tdx: Fetch and validate CPUID of TD guest

[Xiaoyao Li <xiaoyao.li@intel.com>]

On 2/5/2025 5:28 PM, Markus Armbruster wrote:
> Xiaoyao Li <xiaoyao.li@intel.com> writes:
> 
>> Use KVM_TDX_GET_CPUID to get the CPUIDs that are managed and enfored
>> by TDX module for TD guest. Check QEMU's configuration against the
>> fetched data.
>>
>> Print wanring  message when 1. a feature is not supported but requested
>> by QEMU or 2. QEMU doesn't want to expose a feature while it is enforced
>> enabled.
>>
>> - If cpu->enforced_cpuid is not set, prints the warning message of both
>> 1) and 2) and tweak QEMU's configuration.
>>
>> - If cpu->enforced_cpuid is set, quit if any case of 1) or 2).
>>
>> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
>> ---
>>   target/i386/cpu.c     | 33 ++++++++++++++-
>>   target/i386/cpu.h     |  7 +++
>>   target/i386/kvm/tdx.c | 99 +++++++++++++++++++++++++++++++++++++++++++
>>   3 files changed, 137 insertions(+), 2 deletions(-)
>>
>> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
>> index f1330627adbb..a948fd0bd674 100644
>> --- a/target/i386/cpu.c
>> +++ b/target/i386/cpu.c
>> @@ -5482,8 +5482,8 @@ static bool x86_cpu_have_filtered_features(X86CPU *cpu)
>>       return false;
>>   }
>>   
>> -static void mark_unavailable_features(X86CPU *cpu, FeatureWord w, uint64_t mask,
>> -                                      const char *verbose_prefix)
>> +void mark_unavailable_features(X86CPU *cpu, FeatureWord w, uint64_t mask,
>> +                               const char *verbose_prefix)
>>   {
>>       CPUX86State *env = &cpu->env;
>>       FeatureWordInfo *f = &feature_word_info[w];
>> @@ -5510,6 +5510,35 @@ static void mark_unavailable_features(X86CPU *cpu, FeatureWord w, uint64_t mask,
>>       }
>>   }
>>   
>> +void mark_forced_on_features(X86CPU *cpu, FeatureWord w, uint64_t mask,
>> +                             const char *verbose_prefix)
>> +{
>> +    CPUX86State *env = &cpu->env;
>> +    FeatureWordInfo *f = &feature_word_info[w];
>> +    int i;
>> +
>> +    if (!cpu->force_features) {
>> +        env->features[w] |= mask;
>> +    }
>> +
>> +    cpu->forced_on_features[w] |= mask;
>> +
>> +    if (!verbose_prefix) {
>> +        return;
>> +    }
>> +
>> +    for (i = 0; i < 64; ++i) {
>> +        if ((1ULL << i) & mask) {
>> +            g_autofree char *feat_word_str = feature_word_description(f);
> 
> Does not compile for me:
> 
>      ../target/i386/cpu.c: In function ‘mark_forced_on_features’:
>      ../target/i386/cpu.c:5531:46: error: too few arguments to function ‘feature_word_description’
>       5531 |             g_autofree char *feat_word_str = feature_word_description(f);
>            |                                              ^~~~~~~~~~~~~~~~~~~~~~~~
>      ../target/i386/cpu.c:5451:14: note: declared here
>       5451 | static char *feature_word_description(FeatureWordInfo *f, uint32_t bit)
>            |              ^~~~~~~~~~~~~~~~~~~~~~~~

As mentioned in the cover letter, this series depends on a minor one:

https://lore.kernel.org/qemu-devel/20241217123932.948789-1-xiaoyao.li@intel.com/

>> +            warn_report("%s: %s%s%s [bit %d]",
>> +                        verbose_prefix,
>> +                        feat_word_str,
>> +                        f->feat_names[i] ? "." : "",
>> +                        f->feat_names[i] ? f->feat_names[i] : "", i);
>> +        }
>> +    }
>> +}
>> +
>>   static void x86_cpuid_version_get_family(Object *obj, Visitor *v,
>>                                            const char *name, void *opaque,
>>                                            Error **errp)
> 
> [...]
>