On Wed, Feb 13, 2019 at 04:40:00PM +0100, Ard Biesheuvel wrote: > On Wed, 13 Feb 2019 at 16:36, Dave Martin <Dave.Martin@xxxxxxx> wrote: > > > > On Wed, Feb 13, 2019 at 03:30:29PM +0100, Sebastian Andrzej Siewior wrote: > > > On 2019-02-08 16:55:13 [+0000], Julien Grall wrote: > > > > When the kernel is compiled with CONFIG_KERNEL_MODE_NEON, some part of > > > > the kernel may be able to use FPSIMD/SVE. This is for instance the case > > > > for crypto code. > > > > > > > > Any use of FPSIMD/SVE in the kernel are clearly marked by using the > > > > function kernel_neon_{begin, end}. Furthermore, this can only be used > > > > when may_use_simd() returns true. > > > > > > This is equal what x86 is currently doing. The naming is slightly > > > different, there is irq_fpu_usable(). > > > > Yes, I think it's basically the same idea. > > > > It's been evolving a bit on both sides, but is quite similar now. > > > > may_use_simd() only exists because we have a generic crypto SIMD > helper, and so we needed something arch agnostic to wrap around > irq_fpu_usable() [...] Sounds plausible. Cheers ---Dave