Re: [PATCH v3 22/28] arm64/sve: KVM: Prevent guests from using SVE

Catalin Marinas
2017-10-12T17:13:01Z

On Tue, Oct 10, 2017 at 07:38:39PM +0100, Dave P Martin wrote:
> Until KVM has full SVE support, guests must not be allowed to
> execute SVE instructions.
>
> This patch enables the necessary traps, and also ensures that the
> traps are disabled again on exit from the guest so that the host
> can still use SVE if it wants to.
>
> This patch introduces another instance of
> __this_cpu_write(fpsimd_last_state, NULL), so this flush operation
> is abstracted out as a separate helper fpsimd_flush_cpu_state().
> Other instances are ported appropriately.
>
> As a side effect of this refactoring, a this_cpu_write() in
> fpsimd_cpu_pm_notifier() is changed to __this_cpu_write(). This
> should be fine, since cpu_pm_enter() is supposed to be called only
> with interrupts disabled.
>
> Signed-off-by: Dave Martin <Dave.Martin@arm.com>
> Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
> Cc: Marc Zyngier <marc.zyngier@arm.com>
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>

Acked-by: Catalin Marinas <catalin.marinas@arm.com>