numa: call ->ram_block_removed() in ram_block_notifer_remove()

When a RAMBlockNotifier is added, ->ram_block_added() is called with all
existing RAMBlocks. There is no equivalent ->ram_block_removed() call
when a RAMBlockNotifier is removed.

The util/vfio-helpers.c code (the sole user of RAMBlockNotifier) is fine
with this asymmetry because it does not rely on RAMBlockNotifier for
cleanup. It walks its internal list of DMA mappings and unmaps them by
itself.

Future users of RAMBlockNotifier may not have an internal data structure
that records added RAMBlocks so they will need ->ram_block_removed()
callbacks.

This patch makes ram_block_notifier_remove() symmetric with respect to
callbacks. Now util/vfio-helpers.c needs to unmap remaining DMA mappings
after ram_block_notifier_remove() has been called. This is necessary
since users like block/nvme.c may create additional DMA mappings that do
not originate from the RAMBlockNotifier.

Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20221013185908.1297568-4-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

diff --git a/hw/core/numa.c b/hw/core/numa.c
index 26d8e5f61694e7f58f482a3c6e4c9f8e8dc123f2..31e6fe1caa9c39964765e93f2026acb8410983c7 100644 (file)
--- a/hw/core/numa.c
+++ b/hw/core/numa.c
@@ -822,6 +822,19 @@ static int ram_block_notify_add_single(RAMBlock *rb, void *opaque)
     return 0;
 }
 
+static int ram_block_notify_remove_single(RAMBlock *rb, void *opaque)
+{
+    const ram_addr_t max_size = qemu_ram_get_max_length(rb);
+    const ram_addr_t size = qemu_ram_get_used_length(rb);
+    void *host = qemu_ram_get_host_addr(rb);
+    RAMBlockNotifier *notifier = opaque;
+
+    if (host) {
+        notifier->ram_block_removed(notifier, host, size, max_size);
+    }
+    return 0;
+}
+
 void ram_block_notifier_add(RAMBlockNotifier *n)
 {
     QLIST_INSERT_HEAD(&ram_list.ramblock_notifiers, n, next);
@@ -835,6 +848,10 @@ void ram_block_notifier_add(RAMBlockNotifier *n)
 void ram_block_notifier_remove(RAMBlockNotifier *n)
 {
     QLIST_REMOVE(n, next);
+
+    if (n->ram_block_removed) {
+        qemu_ram_foreach_block(ram_block_notify_remove_single, n);
+    }
 }
 
 void ram_block_notify_add(void *host, size_t size, size_t max_size)

diff --git a/util/vfio-helpers.c b/util/vfio-helpers.c
index 5ba01177bf9d2e634c8d69d3a0454af666f790f2..0d1520caac7bfe9cea394d8029bf95fe98157d8d 100644 (file)
--- a/util/vfio-helpers.c
+++ b/util/vfio-helpers.c
@@ -847,10 +847,13 @@ void qemu_vfio_close(QEMUVFIOState *s)
     if (!s) {
         return;
     }
+
+    ram_block_notifier_remove(&s->ram_notifier);
+
     for (i = 0; i < s->nr_mappings; ++i) {
         qemu_vfio_undo_mapping(s, &s->mappings[i], NULL);
     }
-    ram_block_notifier_remove(&s->ram_notifier);
+
     g_free(s->usable_iova_ranges);
     s->nb_iova_ranges = 0;
     qemu_vfio_reset(s);