[PATCH -next v21 11/27] riscv: Allocate user's vector context in the first-use trap

[Conor Dooley]

On Mon, Jun 05, 2023 at 11:07:08AM +0000, Andy Chiu wrote:
> Vector unit is disabled by default for all user processes. Thus, a
> process will take a trap (illegal instruction) into kernel at the first
> time when it uses Vector. Only after then, the kernel allocates V
> context and starts take care of the context for that user process.
> 
> Suggested-by: Richard Henderson <richard.henderson at linaro.org>
> Link: https://lore.kernel.org/r/3923eeee-e4dc-0911-40bf-84c34aee962d@linaro.org
> Signed-off-by: Andy Chiu <andy.chiu at sifive.com>
> ---
> Changelog v21:
>  - Remove has_vector() and use ELF_HWCAP instead. The V bit in the hwcap,
>    if preesents, implies has_vector() returning true. So we can drop
>    has_vector() test here safely, because we also don't handle !V but
>    has_vector() cases.

I think you could probably have carried my R-b from v20, but I realise I
did not reply to you - sorry about that.
The removal of the has_vector() check seems to tally with the
conversation we had on v20, so
Reviewed-by: Conor Dooley <conor.dooley at microchip.com>

Cheers,
Conor.
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