Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Thu, 1 Aug 2019 16:48:14 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Thomas Gleixner <tglx@linutronix.de>
Cc:     LKML <linux-kernel@vger.kernel.org>, x86@kernel.org,
        Ingo Molnar <mingo@kernel.org>,
        Sebastian Siewior <bigeasy@linutronix.de>,
        Anna-Maria Gleixner <anna-maria@linutronix.de>,
        Steven Rostedt <rostedt@goodmis.org>,
        Julia Cartwright <julia@ni.com>,
        Paul McKenney <paulmck@linux.vnet.ibm.com>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Oleg Nesterov <oleg@redhat.com>, kvm@vger.kernel.org,
        Radim Krcmar <rkrcmar@redhat.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        John Stultz <john.stultz@linaro.org>,
        Andy Lutomirski <luto@kernel.org>,
        "Paul E. McKenney" <paulmck@linux.ibm.com>
Subject: Re: [patch 1/5] tracehook: Provide TIF_NOTIFY_RESUME handling for KVM
Message-ID: <20190801144814.GC31398@hirez.programming.kicks-ass.net>
References: <20190801143250.370326052@linutronix.de>
 <20190801143657.785902257@linutronix.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20190801143657.785902257@linutronix.de>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Thu, Aug 01, 2019 at 04:32:51PM +0200, Thomas Gleixner wrote:
> +#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
> +/**
> + * tracehook_handle_notify_resume - Notify resume handling for virt
> + *
> + * Called with interrupts and preemption enabled from VMENTER/EXIT.
> + */
> +void tracehook_handle_notify_resume(void)
> +{
> +	local_irq_disable();
> +	while (test_and_clear_thread_flag(TIF_NOTIFY_RESUME)) {
> +		local_irq_enable();
> +		tracehook_notify_resume(NULL);
> +		local_irq_disable();
> +	}
> +	local_irq_enable();

I'm confused by the IRQ state swizzling here, what is it doing?

> +}
> +EXPORT_SYMBOL_GPL(tracehook_handle_notify_resume);
> +#endif
> 
>