On Fri, Jan 27, 2023 at 7:12 PM Michael S. Tsirkin [off-list ref] wrote:

On Mon, Nov 28, 2022 at 05:14:44AM -0500, Michael S. Tsirkin wrote:

quoted

On Mon, Nov 28, 2022 at 10:10:01AM +0800, Li Zetao wrote:

quoted

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?

At least I will continue the work of IRQ hardening. And this work
could be done on top.

Thanks

quoted

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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(+)

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2.25.1