DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 61E7B61B93
Date: Fri, 31 Mar 2017 19:47:02 +0300
From: "Michael S. Tsirkin" <mst@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Mike Galbraith <efault@gmx.de>,
        Thorsten Leemhuis <linux@leemhuis.info>,
        virtio-dev@lists.oasis-open.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        rjones@redhat.com
Subject: Re: Random guest crashes since 5c34d002dcc7 ("virtio_pci: use shared
 interrupts for virtqueues")
Message-ID: <20170331194416-mutt-send-email-mst@kernel.org>
References: <1490605644.14634.50.camel@gmx.de>
 <20170327170540.GA28715@lst.de>
 <1490638711.26533.44.camel@gmx.de>
 <1490768602.5950.25.camel@gmx.de>
 <20170329230936-mutt-send-email-mst@kernel.org>
 <1490843414.4167.11.camel@gmx.de>
 <1490858435.4696.25.camel@gmx.de>
 <20170331041959-mutt-send-email-mst@kernel.org>
 <20170331032231.GA2471@redhat.com>
 <20170331082049.GA4485@lst.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20170331082049.GA4485@lst.de>
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1218
Lines: 35

On Fri, Mar 31, 2017 at 10:20:49AM +0200, Christoph Hellwig wrote:
> On Fri, Mar 31, 2017 at 06:22:31AM +0300, Michael S. Tsirkin wrote:
> > I'm not sure why does it fail after 32 on 64 bit, but as
> > virtio devices aren't limited to 32 vqs it looks like we
> > should go back to requesting the irq only once for all vqs.
> 
> Meh.
> 
> > 
> > Christoph, should I just revert for now, or do you
> > want to look into a smaller patch for this?
> 
> I think we'll need to do a different patch than just a simple revert,
> mostly because so much infrastructure depends on the patch.
> 
> I'll take a look over the weekend.
> 
> > Another question is looking into intx support - that
> > should work but it seems to be broken at the moment.
> 
> Does it?  I'm pretty sure I tested it back when I came up with the
> series by artifically disabling MSI-X in the kernel.  I can try this
> again, though.

I'm not 100% sure - what I see is that we do not handle failure to
request irqs correctly, we seem to fall back on intx but
the following freeze then blows up trying to free non-existing
vectors.

Does not seem to trigger with just msix off so maybe that is
simply failure to recover from an error correctly.


-- 
MST