Re: [PATCH v2 8/8] x86/fpu/xstate: Restore supervisor xstates for __fpu__restore_sig()

Sebastian Andrzej Siewior
2020-02-28T12:52:02Z

On 2020-02-28 13:17:24 [+0100], Borislav Petkov wrote:
> On Thu, Feb 27, 2020 at 02:52:12PM -0800, Yu-cheng Yu wrote:
> > If TIF_NEED_FPU_LOAD is set, then xstates are already in the xsave buffer.
> > We can skip saving them again.
>
> Ok, then pls use test_and_set_thread_flag().

I've been told not to do this while I crafted kernel_fpu_begin() because
this would introduce an atomic operation which we want avoid.

Sebastian