Subject: Re: [PATCH] xen/events: Fix interrupt lost during irq_disable and
 irq_enable
To: Liu Shuo <shuo.a.liu@intel.com>, linux-kernel@vger.kernel.org
References: <1501347598-15084-1-git-send-email-shuo.a.liu@intel.com>
Cc: Juergen Gross <jgross@suse.com>, Thomas Gleixner <tglx@linutronix.de>,
        David Vrabel <david.vrabel@citrix.com>, Ingo Molnar <mingo@kernel.org>,
        Anoob Soman <anoob.soman@citrix.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Len Brown <len.brown@intel.com>, KarimAllah Ahmed <karahmed@amazon.de>,
        "moderated list:XEN HYPERVISOR INTERFACE" 
        <xen-devel@lists.xenproject.org>
From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Message-ID: <7409e669-89b3-42cc-3bb9-93d99a8aef2b@oracle.com>
Date: Mon, 31 Jul 2017 09:58:07 -0400
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On 07/29/2017 12:59 PM, Liu Shuo wrote:
> Here is a device has xen-pirq-MSI interrupt. Dom0 might lost interrupt
> during driver irq_disable/irq_enable. Here is the scenario,
>  1. irq_disable -> disable_dynirq -> mask_evtchn(irq channel)
>  2. dev interrupt raised by HW and Xen mark its evtchn as pending
>  3. irq_enable -> startup_pirq -> eoi_pirq ->
>     clear_evtchn(channel of irq) -> clear pending status
>  4. consume_one_event process the irq event without pending bit assert
>     which result in interrupt lost once
>  5. No HW interrupt raising anymore.
>
> Now use enable_dynirq for enable_pirq of xen_pirq_chip to remove
> eoi_pirq when irq_enable.
>
> Signed-off-by: Liu Shuo <shuo.a.liu@intel.com>

Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>