[PATCH 2/2] selftest/arm64: Fix sve2p1_sigill() to hwcap test

[wuyifan]

Hi Mark,

On 2/28/2026 9:39 PM, Mark Brown wrote:
> On Fri, Feb 27, 2026 at 11:19:33AM +0800, Yifan Wu wrote:
>> The FEAT_SVE2p1 is indicated by ID_AA64ZFR0_EL1.SVEver. However,
>> the BFADD requires the FEAT_SVE_B16B16, which is indicated by
>> ID_AA64ZFR0_EL1.B16B16. This could cause the test to incorrectly
>> fail on a CPU that supports FEAT_SVE2.1 but not FEAT_SVE_B16B16.
>>
>> LD1Q Gather load quadwords which is decoded from SVE encodings and
>> implied by FEAT_SVE2p1.
> Ah, good spot - I think my search for instructions to use got confused
> by them mention of SVE2 in the description of BFADD.  Since this is a
> fix it should really be patch 1.
>
>> -	/* BFADD Z0.H, Z0.H, Z0.H */
>> -	asm volatile(".inst 0x65000000" : : : "z0");
>> +	/* LD1Q Z0.Q, P0/Z, Z0.D, X0 */
> That should be:
>
> 	LD1Q {Z0.Q}, P0/Z, [Z0.D, X0]
>
> (the existing asm has some issues which we ought to get round fixing but
> may as well keep the new stuff good.)
>
>> +	asm volatile(".inst 0xC400A000" : : : "z0");
> Verified the decode with objdump.  With the above change to the comment:
>
> Reviewed-by: Mark Brown <broonie at kernel.org>
Thanks a lot for the review and the tag! I'll update the comment and re-
order the patches in v2.

Regards,
Yifan Wu