libvhost-user: Fix some memtable remap cases

If a new setmemtable command comes in once the vhost threads are
running, it will remap the guests address space and the threads
will now be looking in the wrong place.

Fortunately we're running this command under lock, so we can
update the queue mappings so that threads will look in the new-right
place.

Note: This doesn't fix things that the threads might be doing
without a lock (e.g. a readv/writev!)  That's for another time.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c
index 63e41062a41b446abf4c14ed35d426c2c80b224b..b89bf18501367998ab2a17dc4556cfd15a9757d0 100644 (file)
--- a/contrib/libvhost-user/libvhost-user.c
+++ b/contrib/libvhost-user/libvhost-user.c
@@ -564,6 +564,21 @@ vu_reset_device_exec(VuDev *dev, VhostUserMsg *vmsg)
     return false;
 }
 
+static bool
+map_ring(VuDev *dev, VuVirtq *vq)
+{
+    vq->vring.desc = qva_to_va(dev, vq->vra.desc_user_addr);
+    vq->vring.used = qva_to_va(dev, vq->vra.used_user_addr);
+    vq->vring.avail = qva_to_va(dev, vq->vra.avail_user_addr);
+
+    DPRINT("Setting virtq addresses:\n");
+    DPRINT("    vring_desc  at %p\n", vq->vring.desc);
+    DPRINT("    vring_used  at %p\n", vq->vring.used);
+    DPRINT("    vring_avail at %p\n", vq->vring.avail);
+
+    return !(vq->vring.desc && vq->vring.used && vq->vring.avail);
+}
+
 static bool
 vu_set_mem_table_exec_postcopy(VuDev *dev, VhostUserMsg *vmsg)
 {
@@ -767,6 +782,14 @@ vu_set_mem_table_exec(VuDev *dev, VhostUserMsg *vmsg)
         close(vmsg->fds[i]);
     }
 
+    for (i = 0; i < dev->max_queues; i++) {
+        if (dev->vq[i].vring.desc) {
+            if (map_ring(dev, &dev->vq[i])) {
+                vu_panic(dev, "remaping queue %d during setmemtable", i);
+            }
+        }
+    }
+
     return false;
 }
 
@@ -853,18 +876,12 @@ vu_set_vring_addr_exec(VuDev *dev, VhostUserMsg *vmsg)
     DPRINT("    avail_user_addr:  0x%016" PRIx64 "\n", vra->avail_user_addr);
     DPRINT("    log_guest_addr:   0x%016" PRIx64 "\n", vra->log_guest_addr);
 
+    vq->vra = *vra;
     vq->vring.flags = vra->flags;
-    vq->vring.desc = qva_to_va(dev, vra->desc_user_addr);
-    vq->vring.used = qva_to_va(dev, vra->used_user_addr);
-    vq->vring.avail = qva_to_va(dev, vra->avail_user_addr);
     vq->vring.log_guest_addr = vra->log_guest_addr;
 
-    DPRINT("Setting virtq addresses:\n");
-    DPRINT("    vring_desc  at %p\n", vq->vring.desc);
-    DPRINT("    vring_used  at %p\n", vq->vring.used);
-    DPRINT("    vring_avail at %p\n", vq->vring.avail);
 
-    if (!(vq->vring.desc && vq->vring.used && vq->vring.avail)) {
+    if (map_ring(dev, vq)) {
         vu_panic(dev, "Invalid vring_addr message");
         return false;
     }

diff --git a/contrib/libvhost-user/libvhost-user.h b/contrib/libvhost-user/libvhost-user.h
index 1844b6f8d4bfa4f6858c50d97443bf1e73d04200..5cb7708559a82e398dd38cffe8a72a929ac77001 100644 (file)
--- a/contrib/libvhost-user/libvhost-user.h
+++ b/contrib/libvhost-user/libvhost-user.h
@@ -327,6 +327,9 @@ typedef struct VuVirtq {
     int err_fd;
     unsigned int enable;
     bool started;
+
+    /* Guest addresses of our ring */
+    struct vhost_vring_addr vra;
 } VuVirtq;
 
 enum VuWatchCondtion {