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libvhost-user: handle removal of identical regions

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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 <stefanha@redhat.com>
Signed-off-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
Message-Id: <20220117041050.19718-7-raphael.norwitz@nutanix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
This commit is contained in:
Raphael Norwitz 2022-01-17 04:12:35 +00:00 committed by Michael S. Tsirkin
parent b906a23c33
commit 4fafedc9da
1 changed files with 16 additions and 12 deletions
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28
subprojects/libvhost-user/libvhost-user.c
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@ -821,6 +821,7 @@ 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_close_fds(vmsg);
@ -856,21 +857,24 @@ 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;
/* Continue the search for eventual duplicates. */
}
}
if (i < dev->nregions) {
/*
* 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--;
if (found) {
vmsg_set_reply_u64(vmsg, 0);
} else {
vu_panic(dev, "Specified region not found\n");