From: Steve Sistare <steven.sist...@oracle.com>
Unlike cpr-reboot mode, cpr-transfer mode cannot save volatile ram blocks
in the migration stream file and recreate them later, because the physical
memory for the blocks is pinned and registered for vfio. Add a blocker
for volatile ram blocks.
Also add a blocker for RAM_GUEST_MEMFD. Preserving guest_memfd may be
sufficient for CPR, but it has not been tested yet.
Signed-off-by: Steve Sistare <steven.sist...@oracle.com>
Reviewed-by: Fabiano Rosas <faro...@suse.de>
Reviewed-by: Peter Xu <pet...@redhat.com>
Reviewed-by: David Hildenbrand <da...@redhat.com>
Message-ID: <1740667681-257312-1-git-send-email-steven.sist...@oracle.com>
Signed-off-by: Fabiano Rosas <faro...@suse.de>
---
include/exec/memory.h | 3 ++
include/exec/ramblock.h | 1 +
migration/savevm.c | 2 ++
system/physmem.c | 66 +++++++++++++++++++++++++++++++++++++++++
4 files changed, 72 insertions(+)
diff --git a/include/exec/memory.h b/include/exec/memory.h
index 78c4e0aec8..d09af58c97 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -3203,6 +3203,9 @@ bool ram_block_discard_is_disabled(void);
*/
bool ram_block_discard_is_required(void);
+void ram_block_add_cpr_blocker(RAMBlock *rb, Error **errp);
+void ram_block_del_cpr_blocker(RAMBlock *rb);
+
#endif
#endif
diff --git a/include/exec/ramblock.h b/include/exec/ramblock.h
index 0babd105c0..64484cd821 100644
--- a/include/exec/ramblock.h
+++ b/include/exec/ramblock.h
@@ -39,6 +39,7 @@ struct RAMBlock {
/* RCU-enabled, writes protected by the ramlist lock */
QLIST_ENTRY(RAMBlock) next;
QLIST_HEAD(, RAMBlockNotifier) ramblock_notifiers;
+ Error *cpr_blocker;
int fd;
uint64_t fd_offset;
int guest_memfd;
diff --git a/migration/savevm.c b/migration/savevm.c
index 5c4fdfd95e..ce158c3512 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -3514,12 +3514,14 @@ void vmstate_register_ram(MemoryRegion *mr, DeviceState
*dev)
qemu_ram_set_idstr(mr->ram_block,
memory_region_name(mr), dev);
qemu_ram_set_migratable(mr->ram_block);
+ ram_block_add_cpr_blocker(mr->ram_block, &error_fatal);
}
void vmstate_unregister_ram(MemoryRegion *mr, DeviceState *dev)
{
qemu_ram_unset_idstr(mr->ram_block);
qemu_ram_unset_migratable(mr->ram_block);
+ ram_block_del_cpr_blocker(mr->ram_block);
}
void vmstate_register_ram_global(MemoryRegion *mr)
diff --git a/system/physmem.c b/system/physmem.c
index a6af555f4b..e97de3ef65 100644
--- a/system/physmem.c
+++ b/system/physmem.c
@@ -71,7 +71,10 @@
#include "qemu/pmem.h"
+#include "qapi/qapi-types-migration.h"
+#include "migration/blocker.h"
#include "migration/cpr.h"
+#include "migration/options.h"
#include "migration/vmstate.h"
#include "qemu/range.h"
@@ -1904,6 +1907,14 @@ static void ram_block_add(RAMBlock *new_block, Error
**errp)
qemu_mutex_unlock_ramlist();
goto out_free;
}
+
+ error_setg(&new_block->cpr_blocker,
+ "Memory region %s uses guest_memfd, "
+ "which is not supported with CPR.",
+ memory_region_name(new_block->mr));
+ migrate_add_blocker_modes(&new_block->cpr_blocker, errp,
+ MIG_MODE_CPR_TRANSFER,
+ -1);
}
ram_size = (new_block->offset + new_block->max_length) >> TARGET_PAGE_BITS;
@@ -4095,3 +4106,58 @@ bool ram_block_discard_is_required(void)
return qatomic_read(&ram_block_discard_required_cnt) ||
qatomic_read(&ram_block_coordinated_discard_required_cnt);
}
+
+/*
+ * Return true if ram is compatible with CPR. Do not exclude rom,
+ * because the rom file could change in new QEMU.
+ */
+static bool ram_is_cpr_compatible(RAMBlock *rb)
+{
+ MemoryRegion *mr = rb->mr;
+
+ if (!mr || !memory_region_is_ram(mr)) {
+ return true;
+ }
+
+ /* Ram device is remapped in new QEMU */
+ if (memory_region_is_ram_device(mr)) {
+ return true;
+ }
+
+ /*
+ * A file descriptor is passed to new QEMU and remapped, or its backing
+ * file is reopened and mapped. It must be shared to avoid COW.
+ */
+ if (rb->fd >= 0 && qemu_ram_is_shared(rb)) {
+ return true;
+ }
+
+ return false;
+}
+
+/*
+ * Add a blocker for each volatile ram block. This function should only be
+ * called after we know that the block is migratable. Non-migratable blocks
+ * are either re-created in new QEMU, or are handled specially, or are covered
+ * by a device-level CPR blocker.
+ */
+void ram_block_add_cpr_blocker(RAMBlock *rb, Error **errp)
+{
+ assert(qemu_ram_is_migratable(rb));
+
+ if (ram_is_cpr_compatible(rb)) {
+ return;
+ }
+
+ error_setg(&rb->cpr_blocker,
+ "Memory region %s is not compatible with CPR. share=on is "
+ "required for memory-backend objects, and aux-ram-share=on is "
+ "required.", memory_region_name(rb->mr));
+ migrate_add_blocker_modes(&rb->cpr_blocker, errp, MIG_MODE_CPR_TRANSFER,
+ -1);
+}
+
+void ram_block_del_cpr_blocker(RAMBlock *rb)
+{
+ migrate_del_blocker(&rb->cpr_blocker);
+}
--
2.35.3
