linux-kernel - Re: [PATCH 1/2] x86/entry: Avoid interrupt flag save and restore

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Message-ID: <CALCETrXLiZCun=C20U=kwovi2oAiKmhybiNpS1W65DvQ4BBnew@mail.gmail.com>
Date:	Mon, 20 Jun 2016 13:34:34 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	Paolo Bonzini <pbonzini@...hat.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	kvm list <kvm@...r.kernel.org>,
	Andy Lutomirski <luto@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Rik van Riel <riel@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 1/2] x86/entry: Avoid interrupt flag save and restore

On Mon, Jun 20, 2016 at 7:58 AM, Paolo Bonzini <pbonzini@...hat.com> wrote:
> Thanks to all the work that was done by Andy Lutomirski and others,
> enter_from_user_mode and prepare_exit_to_usermode are now called only with
> interrupts disabled.  Let's provide them a version of user_enter/user_exit
> that skips saving and restoring the interrupt flag.

You're also skipping the in_interrupt() check, but that appears to be fine.

Reviewed-by: Andy Lutomirski <luto@...nel.org>