Re: [PATCH qemu-server v2] query-machine-capabilities: limit AuthenticAMD and GenuineIntel checks to x86-64

[Kaiyang Wu <wukaiyang2003@gmail.com>]

On 7/29/26 23:33, Fiona Ebner wrote:
> Am 29.07.26 um 1:11 PM schrieb Kaiyang Wu:
>> Intel TDX and AMD SEV are both x86-64-only extensions [0] [1]. The current
>> method of checking results in compilation errors on "unknown" vendors,
>> where the current placeholder string length ("Unknown") mismatches the
>> lengths of both "AuthenticAMD" and "GenuineIntel":
>>
>> error: ‘strncmp’ of strings of length 7 and 12 and bound of 12
>> evaluates to nonzero [-Werror=string-compare]
>>
>> Limit the machine capability checks for Intel TDX and AMD SEV to x86-64 to
>> fix build.
>>
>> [0]: https://docs.kernel.org/arch/x86/tdx.html
>> [1]: https://docs.kernel.org/virt/kvm/x86/amd-memory-encryption.html
>>
>> Signed-off-by: Kaiyang Wu <wukaiyang@loongfans.cn>
>> ---
>>
>> v1: https://lore.proxmox.com/pve-devel/20260603055031.106241-1-wukaiyang@loongfans.cn/
>>
>> Changes v1 -> v2:
>> - Use conditional compilation to limit Intel TDX and AMD SEV checks to x86-64
>> - Eliminate the vendor string length check
>>
>> src/query-machine-capabilities/query-machine-capabilities.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/src/query-machine-capabilities/query-machine-capabilities.c b/src/query-machine-capabilities/query-machine-capabilities.c
>> index abb47acd..3ccd30da 100644
>> --- a/src/query-machine-capabilities/query-machine-capabilities.c
>> +++ b/src/query-machine-capabilities/query-machine-capabilities.c
>> @@ -204,6 +204,7 @@ int main() {
>> eprintf("Error writing to file '" OUTPUT_PATH "': %s\n", strerror(errno));
>> }
>>
>> +#ifdef __x86_64__
>> if (strncmp(vendor, "AuthenticAMD", 12) == 0) {
>> cpu_caps_amd_sev_t caps_sev;
>> query_cpu_capabilities_sev(&caps_sev);
>> @@ -233,7 +234,7 @@ int main() {
>> );
>> }
>> }
>> -#ifdef __aarch64__
>> +#elif defined(__aarch64__)
>> else {
>
> I guess this won't compile on aarch64 now, as there will be an else
> without an if?

I will fix this in v3. Thank you for pointing it out.

>
>> cpu_caps_arm_t caps_arm;
>> query_cpu_capabilities_arm(&caps_arm);
>
>
> Also, did you already submit a signed CLA to office@proxmox.com? See:
> https://pve.proxmox.com/wiki/Developer_Documentation#Software_License_and_Copyright
>

Yes, I have already submitted a signed CLA for my entity (sent from
this email address on May 28, 2026).