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Blame 0100-libvhost-user-Fix-some-memtable-remap-cases.patch

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From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
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Date: Mon, 27 Jan 2020 19:02:09 +0000
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Subject: [PATCH] libvhost-user: Fix some memtable remap cases
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If a new setmemtable command comes in once the vhost threads are
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running, it will remap the guests address space and the threads
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will now be looking in the wrong place.
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Fortunately we're running this command under lock, so we can
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update the queue mappings so that threads will look in the new-right
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place.
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Note: This doesn't fix things that the threads might be doing
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without a lock (e.g. a readv/writev!)  That's for another time.
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Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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(cherry picked from commit 49e9ec749d4db62ae51f76354143cee183912a1d)
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---
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 contrib/libvhost-user/libvhost-user.c | 33 ++++++++++++++++++++-------
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 contrib/libvhost-user/libvhost-user.h |  3 +++
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 2 files changed, 28 insertions(+), 8 deletions(-)
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diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c
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index 63e41062a4..b89bf18501 100644
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--- a/contrib/libvhost-user/libvhost-user.c
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+++ b/contrib/libvhost-user/libvhost-user.c
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@@ -564,6 +564,21 @@ vu_reset_device_exec(VuDev *dev, VhostUserMsg *vmsg)
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     return false;
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 }
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+static bool
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+map_ring(VuDev *dev, VuVirtq *vq)
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+{
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+    vq->vring.desc = qva_to_va(dev, vq->vra.desc_user_addr);
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+    vq->vring.used = qva_to_va(dev, vq->vra.used_user_addr);
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+    vq->vring.avail = qva_to_va(dev, vq->vra.avail_user_addr);
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+
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+    DPRINT("Setting virtq addresses:\n");
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+    DPRINT("    vring_desc  at %p\n", vq->vring.desc);
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+    DPRINT("    vring_used  at %p\n", vq->vring.used);
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+    DPRINT("    vring_avail at %p\n", vq->vring.avail);
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+
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+    return !(vq->vring.desc && vq->vring.used && vq->vring.avail);
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+}
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+
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 static bool
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 vu_set_mem_table_exec_postcopy(VuDev *dev, VhostUserMsg *vmsg)
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 {
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@@ -767,6 +782,14 @@ vu_set_mem_table_exec(VuDev *dev, VhostUserMsg *vmsg)
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         close(vmsg->fds[i]);
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     }
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+    for (i = 0; i < dev->max_queues; i++) {
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+        if (dev->vq[i].vring.desc) {
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+            if (map_ring(dev, &dev->vq[i])) {
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+                vu_panic(dev, "remaping queue %d during setmemtable", i);
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+            }
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+        }
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+    }
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+
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     return false;
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 }
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@@ -853,18 +876,12 @@ vu_set_vring_addr_exec(VuDev *dev, VhostUserMsg *vmsg)
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     DPRINT("    avail_user_addr:  0x%016" PRIx64 "\n", vra->avail_user_addr);
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     DPRINT("    log_guest_addr:   0x%016" PRIx64 "\n", vra->log_guest_addr);
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+    vq->vra = *vra;
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     vq->vring.flags = vra->flags;
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-    vq->vring.desc = qva_to_va(dev, vra->desc_user_addr);
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-    vq->vring.used = qva_to_va(dev, vra->used_user_addr);
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-    vq->vring.avail = qva_to_va(dev, vra->avail_user_addr);
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     vq->vring.log_guest_addr = vra->log_guest_addr;
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-    DPRINT("Setting virtq addresses:\n");
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-    DPRINT("    vring_desc  at %p\n", vq->vring.desc);
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-    DPRINT("    vring_used  at %p\n", vq->vring.used);
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-    DPRINT("    vring_avail at %p\n", vq->vring.avail);
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-    if (!(vq->vring.desc && vq->vring.used && vq->vring.avail)) {
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+    if (map_ring(dev, vq)) {
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         vu_panic(dev, "Invalid vring_addr message");
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         return false;
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     }
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diff --git a/contrib/libvhost-user/libvhost-user.h b/contrib/libvhost-user/libvhost-user.h
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index 1844b6f8d4..5cb7708559 100644
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--- a/contrib/libvhost-user/libvhost-user.h
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+++ b/contrib/libvhost-user/libvhost-user.h
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@@ -327,6 +327,9 @@ typedef struct VuVirtq {
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     int err_fd;
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     unsigned int enable;
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     bool started;
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+
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+    /* Guest addresses of our ring */
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+    struct vhost_vring_addr vra;
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 } VuVirtq;
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 enum VuWatchCondtion {