On 7/11/2017 12:56 AM, Borislav Petkov wrote:
> On Tue, Jul 11, 2017 at 01:07:46AM -0400, Brian Gerst wrote:
>>> If I make the scattered feature support conditional on CONFIG_X86_64
>>> (based on comment below) then cpu_has() will always be false unless
>>> CONFIG_X86_64 is enabled. So this won't need to be wrapped by the
>>> #ifdef.
>>
>> If you change it to use cpu_feature_enabled(), gcc will see that it is
>> disabled and eliminate the dead code at compile time.
>
> Just do this:
>
> if (cpu_has(c, X86_FEATURE_SME)) {
> if (IS_ENABLED(CONFIG_X86_32)) {
> clear_cpu_cap(c, X86_FEATURE_SME);
> } else {
> u64 msr;
>
> /* Check if SME is enabled */
> rdmsrl(MSR_K8_SYSCFG, msr);
> if (!(msr & MSR_K8_SYSCFG_MEM_ENCRYPT))
> clear_cpu_cap(c, X86_FEATURE_SME);
> }
> }
>
> so that it is explicit that we disable it on 32-bit and we can save us
> the ifdeffery elsewhere.
I'll use this method for the change and avoid the #ifdefs.
Thanks,
Tom
>
> Thanks.
>
