On Wed, 16 Mar 2011 19:12:10 +0530, Amit Shah <amit.shah@xxxxxxxxxx> wrote: > When detaching a buffer from a vq, the avail.idx value should be > decremented as well. > > This was noticed by hot-unplugging a virtio console port and then > plugging in a new one on the same number (re-using the vqs which were > just 'disowned'). qemu reported > > 'Guest moved used index from 0 to 256' > > when any IO was attempted on the new port. Yech... detach_unused_buf cannot be used on a live virtqueue; it assumes we will reset the vq (usually by resetting the entire device). You've partially violated that assumption by reusing the vq after calling detach_unused_buf. So I'm not entirely sure this is the only bug lurking; safer would be to re-initialize the vq somehow when you plug back in... (Though this patch is minimal, and may be better -stable material). Thanks, Rusty. _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/virtualization
