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Message-ID: <20230127061055-mutt-send-email-mst@kernel.org>
Date: Fri, 27 Jan 2023 06:11:49 -0500
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Li Zetao <lizetao1@...wei.com>
Cc: jasowang@...hat.com, pbonzini@...hat.com, stefanha@...hat.com,
axboe@...nel.dk, kraxel@...hat.com, david@...hat.com,
ericvh@...il.com, lucho@...kov.net, asmadeus@...ewreck.org,
linux_oss@...debyte.com, davem@...emloft.net, edumazet@...gle.com,
kuba@...nel.org, pabeni@...hat.com, rusty@...tcorp.com.au,
virtualization@...ts.linux-foundation.org,
linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
v9fs-developer@...ts.sourceforge.net, netdev@...r.kernel.org
Subject: Re: [PATCH 0/4] Fix probe failed when modprobe modules
On Mon, Nov 28, 2022 at 05:14:44AM -0500, Michael S. Tsirkin wrote:
> On Mon, Nov 28, 2022 at 10:10:01AM +0800, Li Zetao wrote:
> > This patchset fixes similar issue, the root cause of the
> > problem is that the virtqueues are not stopped on error
> > handling path.
>
> I've been thinking about this.
> Almost all drivers are affected.
>
> The reason really is that it used to be the right thing to do:
> On legacy pci del_vqs writes 0
> into vq index and this resets the device as a side effect
> (we actually do this multiple times, what e.g. writes of MSI vector
> after the 1st reset do I have no idea).
>
> mmio ccw and modern pci don't.
>
> Given this has been with us for a while I am inlined to look for
> a global solution rather than tweaking each driver.
>
> Given many drivers are supposed to work on legacy too, we know del_vqs
> includes a reset for many of them. So I think I see a better way to do
> this:
>
> Add virtio_reset_device_and_del_vqs()
>
> and convert all drivers to that.
>
> When doing this, we also need to/can fix a related problem (and related
> to the hardening that Jason Wang was looking into):
> virtio_reset_device is inherently racy: vq interrupts could
> be in flight when we do reset. We need to prevent handlers from firing in
> the window between reset and freeing the irq, so we should first
> free irqs and only then start changing the state by e.g.
> device reset.
>
>
> Quite a lot of core work here. Jason are you still looking into
> hardening?
>
Li Zetao, Jason, any updates. You guys looking into this?
>
> > Li Zetao (4):
> > 9p: Fix probe failed when modprobe 9pnet_virtio
> > virtio-mem: Fix probe failed when modprobe virtio_mem
> > virtio-input: Fix probe failed when modprobe virtio_input
> > virtio-blk: Fix probe failed when modprobe virtio_blk
> >
> > drivers/block/virtio_blk.c | 1 +
> > drivers/virtio/virtio_input.c | 1 +
> > drivers/virtio/virtio_mem.c | 1 +
> > net/9p/trans_virtio.c | 1 +
> > 4 files changed, 4 insertions(+)
> >
> > --
> > 2.25.1
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