Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Mon, 07 Mar 2022 14:03:17 +0000
Message-ID: <878rtl272y.wl-maz@kernel.org>
From:   Marc Zyngier <maz@kernel.org>
To:     John Garry <john.garry@huawei.com>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        chenxiang <chenxiang66@hisilicon.com>,
        Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "liuqi (BA)" <liuqi115@huawei.com>, <wangxiongfeng2@huawei.com>,
        David Decotigny <decot@google.com>
Subject: Re: PCI MSI issue for maxcpus=1
In-Reply-To: <87a6e1276p.wl-maz@kernel.org>
References: <78615d08-1764-c895-f3b7-bfddfbcbdfb9@huawei.com>
        <87a6g8vp8k.wl-maz@kernel.org>
        <19d55cdf-9ef7-e4a3-5ae5-0970f0d7751b@huawei.com>
        <87v8yjyjc0.wl-maz@kernel.org>
        <87k0ey9122.wl-maz@kernel.org>
        <5f529b4e-1f6c-5a7d-236c-09ebe3a7db29@huawei.com>
        <1cbe7daa-8003-562b-06fa-5a50f7ee6ed2@huawei.com>
        <87a6e4tnkm.wl-maz@kernel.org>
        <452d97ed-459f-7936-99e4-600380608615@huawei.com>
        <87a6e1276p.wl-maz@kernel.org>
User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue)
 FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1
 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO)
MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue")
Content-Type: text/plain; charset=US-ASCII
Precedence: bulk

On Mon, 07 Mar 2022 14:01:02 +0000,
Marc Zyngier <maz@kernel.org> wrote:
> 
> Hi John,
> 
> On Mon, 07 Mar 2022 13:48:11 +0000,
> John Garry <john.garry@huawei.com> wrote:
> > 
> > Hi Marc,
> > 
> > > 
> > > diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
> > > index 2bdfce5edafd..97e9eb9aecc6 100644
> > > --- a/kernel/irq/msi.c
> > > +++ b/kernel/irq/msi.c
> > > @@ -823,6 +823,19 @@ static int msi_init_virq(struct irq_domain *domain, int virq, unsigned int vflag
> > >   	if (!(vflags & VIRQ_ACTIVATE))
> > >   		return 0;
> > >   +	if (!(vflags & VIRQ_CAN_RESERVE)) {
> > > +		/*
> > > +		 * If the interrupt is managed but no CPU is available
> > > +		 * to service it, shut it down until better times.
> > > +		 */
> > > +		if (irqd_affinity_is_managed(irqd) &&
> > > +		    !cpumask_intersects(irq_data_get_affinity_mask(irqd),
> > > +					cpu_online_mask)) {
> > > +			irqd_set_managed_shutdown(irqd);
> > > +			return 0;
> > > +		}
> > > +	}
> > > +
> > >   	ret = irq_domain_activate_irq(irqd, vflags & VIRQ_CAN_RESERVE);
> > >   	if (ret)
> > >   		return ret;
> > > 
> > 
> > Yeah, that seems to solve the issue. I will test it a bit more.
> 
> Thanks. For the record, I have pushed a branch at [1]. The patch is
> extremely similar, just moved up a tiny bit to avoid duplicating the
> !VIRQ_CAN_RESERVE case.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/log/?h=irq/msi-shutdown-on-init

-- 
Without deviation from the norm, progress is not possible.