* Re: [PATCH 1/1] s390/virtio: handle find on invalid queue gracefully
[not found] <20190107123147.97038-1-pasic@linux.ibm.com>
@ 2019-01-07 15:06 ` Cornelia Huck
0 siblings, 0 replies; only message in thread
From: Cornelia Huck @ 2019-01-07 15:06 UTC (permalink / raw)
To: Halil Pasic; +Cc: linux-s390, kvm, virtualization
On Mon, 7 Jan 2019 13:31:46 +0100
Halil Pasic <pasic@linux.ibm.com> wrote:
> A queue with a capacity of zero is clearly not a valid virtio queue.
> Some emulators report zero queue size if queried with an invalid queue
> index. Instead of crashing in this case let us just return -EINVAL. To
s/-EINVAL/-ENOENT/
> make that work properly, let us fix the notifier cleanup logic as well.
>
> Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
> ---
> This patch is motivated by commit 86a5597 "virtio-balloon:
> VIRTIO_BALLOON_F_FREE_PAGE_HINT" (Wei Wang, 2018-08-27) which triggered
> the described scenario. The emulator in question is the current QEMU.
> The problem we run into is the underflow in the following loop
> in __vring_new_virtqueue():
> for (i = 0; i < vring.num-1; i++)
> vq->vring.desc[i].next = cpu_to_virtio16(vdev, i + 1)
> Namely vring.num is an unsigned int.
>
> RFC --> v1:
> * Change error code from -EINVAL to -ENOENT, so we are in line with the
> other transports.
> * Push down the detection of the error into virtio_ccw_read_vq_conf().
> ---
> drivers/s390/virtio/virtio_ccw.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
Thanks, applied.
^ permalink raw reply [flat|nested] only message in thread