Re: [PATCH v10 05/28] x86/fpu/xstate: Add a new variable to indicate dynamic user states

[Bae, Chang Seok]

On Oct 1, 2021, at 06:16, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
> On Wed, Aug 25 2021 at 08:53, Chang S. Bae wrote:
>> +/*
>> + * This represents user xstates, a subset of xfeatures_mask_all, saved in a
>> + * dynamic kernel XSAVE buffer.
>> + */
>> +u64 xfeatures_mask_user_dynamic __ro_after_init;
>> +
>> static unsigned int xstate_offsets[XFEATURE_MAX] __ro_after_init =
>> 	{ [ 0 ... XFEATURE_MAX - 1] = -1};
>> static unsigned int xstate_sizes[XFEATURE_MAX] __ro_after_init =
>> @@ -709,6 +715,7 @@ static int __init init_xstate_size(void)
>> static void fpu__init_disable_system_xstate(void)
>> {
>> 	xfeatures_mask_all = 0;
>> +	xfeatures_mask_user_dynamic = 0;
> 
> It's zero at boot already, isn't it?

I thought of this as a safety net here when it was introduced.

But let me move it to patch13 [1] where the variable is updated.

Thanks,
Chang

[1] https://lore.kernel.org/lkml/20210825155413.19673-14-chang.seok.bae@xxxxxxxxx/