@@ -18,6 +18,7 @@
#include "sysemu/numa.h"
#include "sysemu/sysemu.h"
#include "sysemu/reset.h"
+#include "sysemu/runstate.h"
#include "hw/virtio/virtio.h"
#include "hw/virtio/virtio-bus.h"
#include "hw/virtio/virtio-mem.h"
@@ -901,11 +902,23 @@ static void virtio_mem_device_realize(DeviceState *dev, Error **errp)
return;
}
- ret = ram_block_discard_range(rb, 0, qemu_ram_get_used_length(rb));
- if (ret) {
- error_setg_errno(errp, -ret, "Unexpected error discarding RAM");
- ram_block_coordinated_discard_require(false);
- return;
+ /*
+ * We don't know at this point whether shared RAM is migrated using
+ * QEMU or migrated using the file content. "x-ignore-shared" will be
+ * configured after realizing the device. So in case we have an
+ * incoming migration, simply always skip the discard step.
+ *
+ * Otherwise, make sure that we start with a clean slate: either the
+ * memory backend might get reused or the shared file might still have
+ * memory allocated.
+ */
+ if (!runstate_check(RUN_STATE_INMIGRATE)) {
+ ret = ram_block_discard_range(rb, 0, qemu_ram_get_used_length(rb));
+ if (ret) {
+ error_setg_errno(errp, -ret, "Unexpected error discarding RAM");
+ ram_block_coordinated_discard_require(false);
+ return;
+ }
}
virtio_mem_resize_usable_region(vmem, vmem->requested_size, true);
@@ -977,10 +990,6 @@ static int virtio_mem_post_load(void *opaque, int version_id)
RamDiscardListener *rdl;
int ret;
- if (vmem->prealloc && !vmem->early_migration) {
- warn_report("Proper preallocation with migration requires a newer QEMU machine");
- }
-
/*
* We started out with all memory discarded and our memory region is mapped
* into an address space. Replay, now that we updated the bitmap.
@@ -993,6 +1002,18 @@ static int virtio_mem_post_load(void *opaque, int version_id)
}
}
+ /*
+ * If shared RAM is migrated using the file content and not using QEMU,
+ * don't mess with preallocation and postcopy.
+ */
+ if (migrate_ram_is_ignored(vmem->memdev->mr.ram_block)) {
+ return 0;
+ }
+
+ if (vmem->prealloc && !vmem->early_migration) {
+ warn_report("Proper preallocation with migration requires a newer QEMU machine");
+ }
+
if (migration_in_incoming_postcopy()) {
return 0;
}
@@ -1025,6 +1046,14 @@ static int virtio_mem_post_load_early(void *opaque, int version_id)
return 0;
}
+ /*
+ * If shared RAM is migrated using the file content and not using QEMU,
+ * don't mess with preallocation and postcopy.
+ */
+ if (migrate_ram_is_ignored(rb)) {
+ return 0;
+ }
+
/*
* We restored the bitmap and verified that the basic properties
* match on source and destination, so we can go ahead and preallocate
To achieve desired "x-ignore-shared" functionality, we should not discard all RAM when realizing the device and not mess with preallocation/postcopy when loading device state. In essence, we should not touch RAM content. As "x-ignore-shared" gets set after realizing the device, we cannot rely on that. Let's simply skip discarding of RAM on incoming migration. Note that virtio_mem_post_load() will call virtio_mem_restore_unplugged() -- unless "x-ignore-shared" is set. So once migration finished we'll have a consistent state. The initial system reset will also not discard any RAM, because virtio_mem_unplug_all() will not call virtio_mem_unplug_all() when no memory is plugged (which is the case before loading the device state). Note that something like VM templating -- see commit b17fbbe55cba ("migration: allow private destination ram with x-ignore-shared") -- is currently incompatible with virtio-mem and ram_block_discard_range() will warn in case a private file mapping is supplied by virtio-mem. For VM templating with virtio-mem, it makes more sense to either (a) Create the template without the virtio-mem device and hotplug a virtio-mem device to the new VM instances using proper own memory backend. (b) Use a virtio-mem device that doesn't provide any memory in the template (requested-size=0) and use private anonymous memory. Message-ID: <20230706075612.67404-5-david@redhat.com> Tested-by: Mario Casquero <mcasquer@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> --- hw/virtio/virtio-mem.c | 47 ++++++++++++++++++++++++++++++++++-------- 1 file changed, 38 insertions(+), 9 deletions(-)