On 06.01.22 07:47, Raphael Norwitz wrote:
> Today if QEMU (or any other VMM) has sent multiple copies of the same
> region to a libvhost-user based backend and then attempts to remove the
> region, only one instance of the region will be removed, leaving stale
> copies of the region in dev->regions[].
>
> This change resolves this by having vu_rem_mem_reg() iterate through all
> regions in dev->regions[] and delete all matching regions.
>
> Suggested-by: Stefan Hajnoczi <stefa...@redhat.com>
> Signed-off-by: Raphael Norwitz <raphael.norw...@nutanix.com>
> ---
> subprojects/libvhost-user/libvhost-user.c | 26 ++++++++++++-----------
> 1 file changed, 14 insertions(+), 12 deletions(-)
>
> diff --git a/subprojects/libvhost-user/libvhost-user.c
> b/subprojects/libvhost-user/libvhost-user.c
> index 0fe3aa155b..14482484d3 100644
> --- a/subprojects/libvhost-user/libvhost-user.c
> +++ b/subprojects/libvhost-user/libvhost-user.c
> @@ -809,6 +809,7 @@ static bool
> vu_rem_mem_reg(VuDev *dev, VhostUserMsg *vmsg) {
> VhostUserMemoryRegion m = vmsg->payload.memreg.region, *msg_region = &m;
> int i;
> + bool found = false;
>
> if (vmsg->fd_num != 1 ||
> vmsg->size != sizeof(vmsg->payload.memreg)) {
> @@ -835,21 +836,22 @@ vu_rem_mem_reg(VuDev *dev, VhostUserMsg *vmsg) {
> munmap(m, r->size + r->mmap_offset);
> }
>
> - break;
> + /*
> + * Shift all affected entries by 1 to close the hole at index i
> and
> + * zero out the last entry.
> + */
> + memmove(dev->regions + i, dev->regions + i + 1,
> + sizeof(VuDevRegion) * (dev->nregions - i - 1));
> + memset(dev->regions + dev->nregions - 1, 0, sizeof(VuDevRegion));
> + DPRINT("Successfully removed a region\n");
> + dev->nregions--;
> + i--;
> +
> + found = true;
Maybe add a comment like
/* Continue the search for eventual duplicates. */
--
Thanks,
David / dhildenb
