Re: [PATCH v4 06/39] x86/fpu: Add helper for modifying xstate

Borislav Petkov
2022-12-20T12:04:50Z

On Fri, Dec 02, 2022 at 04:35:33PM -0800, Rick Edgecombe wrote:
> +void fpregs_lock_and_load(void)

Fun naming :)

> +{
> + /*
> + * fpregs_lock() only disables preemption (mostly). So modifing state

Unknown word [modifing] in comment.
Suggestions: ['modifying',...

> + * in an interrupt could screw up some in progress fpregs operation,
> + * but appear to work. Warn about it.
> + */
> + WARN_ON_ONCE(!irq_fpu_usable());
> + WARN_ON_ONCE(current->flags & PF_KTHREAD);
> +
> + fpregs_lock();

So it locks them here...

/me goes further into the patchset

aha, and the counterpart of this function is fpregs_unlock() so
everything gets sandwitched between the two.

Ok, I guess.

> +EXPORT_SYMBOL_GPL(fpregs_lock_and_load);

Exported for KVM?

--
Regards/Gruss,
Boris.