util: vfio-helpers: Factor out and fix processing of existing ram blocks

Factor it out into common code when a new notifier is registered, just
as done with the memory region notifier. This keeps logic about how to
process existing ram blocks at a central place.

Just like when adding a new ram block, we have to register the max_length.
Ram blocks are only "fake resized". All memory (max_length) is mapped.

Print the warning from inside qemu_vfio_ram_block_added().

Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20210429112708.12291-2-david@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

hw/core/numa.c

@@ -802,9 +802,23 @@ void query_numa_node_mem(NumaNodeMem node_mem[], MachineState *ms)
     }
 }
 
+static int ram_block_notify_add_single(RAMBlock *rb, void *opaque)
+{
+    const ram_addr_t max_size = qemu_ram_get_max_length(rb);
+    void *host = qemu_ram_get_host_addr(rb);
+    RAMBlockNotifier *notifier = opaque;
+
+    if (host) {
+        notifier->ram_block_added(notifier, host, max_size);
+    }
+    return 0;
+}
+
 void ram_block_notifier_add(RAMBlockNotifier *n)
 {
     QLIST_INSERT_HEAD(&ram_list.ramblock_notifiers, n, next);
+    /* Notify about all existing ram blocks. */
+    qemu_ram_foreach_block(ram_block_notify_add_single, n);
 }
 
 void ram_block_notifier_remove(RAMBlockNotifier *n)

include/exec/cpu-common.h

@@ -57,6 +57,7 @@ const char *qemu_ram_get_idstr(RAMBlock *rb);
 void *qemu_ram_get_host_addr(RAMBlock *rb);
 ram_addr_t qemu_ram_get_offset(RAMBlock *rb);
 ram_addr_t qemu_ram_get_used_length(RAMBlock *rb);
+ram_addr_t qemu_ram_get_max_length(RAMBlock *rb);
 bool qemu_ram_is_shared(RAMBlock *rb);
 bool qemu_ram_is_uf_zeroable(RAMBlock *rb);
 void qemu_ram_set_uf_zeroable(RAMBlock *rb);

softmmu/physmem.c

@@ -1694,6 +1694,11 @@ ram_addr_t qemu_ram_get_used_length(RAMBlock *rb)
     return rb->used_length;
 }
 
+ram_addr_t qemu_ram_get_max_length(RAMBlock *rb)
+{
+    return rb->max_length;
+}
+
 bool qemu_ram_is_shared(RAMBlock *rb)
 {
     return rb->flags & RAM_SHARED;

util/vfio-helpers.c

@@ -463,8 +463,14 @@ static void qemu_vfio_ram_block_added(RAMBlockNotifier *n,
                                       void *host, size_t size)
 {
     QEMUVFIOState *s = container_of(n, QEMUVFIOState, ram_notifier);
+    int ret;
+
     trace_qemu_vfio_ram_block_added(s, host, size);
-    qemu_vfio_dma_map(s, host, size, false, NULL);
+    ret = qemu_vfio_dma_map(s, host, size, false, NULL);
+    if (ret) {
+        error_report("qemu_vfio_dma_map(%p, %zu) failed: %s", host, size,
+                     strerror(-ret));
+    }
 }
 
 static void qemu_vfio_ram_block_removed(RAMBlockNotifier *n,
@@ -477,33 +483,14 @@ static void qemu_vfio_ram_block_removed(RAMBlockNotifier *n,
     }
 }
 
-static int qemu_vfio_init_ramblock(RAMBlock *rb, void *opaque)
-{
-    void *host_addr = qemu_ram_get_host_addr(rb);
-    ram_addr_t length = qemu_ram_get_used_length(rb);
-    int ret;
-    QEMUVFIOState *s = opaque;
-
-    if (!host_addr) {
-        return 0;
-    }
-    ret = qemu_vfio_dma_map(s, host_addr, length, false, NULL);
-    if (ret) {
-        fprintf(stderr, "qemu_vfio_init_ramblock: failed %p %" PRId64 "\n",
-                host_addr, (uint64_t)length);
-    }
-    return 0;
-}
-
 static void qemu_vfio_open_common(QEMUVFIOState *s)
 {
     qemu_mutex_init(&s->lock);
     s->ram_notifier.ram_block_added = qemu_vfio_ram_block_added;
     s->ram_notifier.ram_block_removed = qemu_vfio_ram_block_removed;
-    ram_block_notifier_add(&s->ram_notifier);
     s->low_water_mark = QEMU_VFIO_IOVA_MIN;
     s->high_water_mark = QEMU_VFIO_IOVA_MAX;
-    qemu_ram_foreach_block(qemu_vfio_init_ramblock, s);
+    ram_block_notifier_add(&s->ram_notifier);
 }
 
 /**