include/exec/memory.h | 3 +++ include/exec/ramblock.h | 1 + migration/savevm.c | 2 ++ system/physmem.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 72 insertions(+)
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.sistare@oracle.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
---
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 9f73b59..ea5d33a 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -3184,6 +3184,9 @@ 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 0babd10..64484cd 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 bc375db..85a3559 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -3315,12 +3315,14 @@ 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 67c9db9..0e84f14 100644
--- a/system/physmem.c
+++ b/system/physmem.c
@@ -70,7 +70,10 @@
#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"
@@ -1899,6 +1902,14 @@ 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;
@@ -4059,3 +4070,58 @@ 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);
+}
--
1.8.3.1Steve Sistare <steven.sistare@oracle.com> writes:
> 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.sistare@oracle.com>
> Reviewed-by: Fabiano Rosas <farosas@suse.de>
> Reviewed-by: Peter Xu <peterx@redhat.com>
> Reviewed-by: David Hildenbrand <david@redhat.com>
> ---
> 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 9f73b59..ea5d33a 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -3184,6 +3184,9 @@ 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 0babd10..64484cd 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 bc375db..85a3559 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -3315,12 +3315,14 @@ 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 67c9db9..0e84f14 100644
> --- a/system/physmem.c
> +++ b/system/physmem.c
> @@ -70,7 +70,10 @@
>
> #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"
> @@ -1899,6 +1902,14 @@ 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;
> @@ -4059,3 +4070,58 @@ 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);
> +}
I assume this is good for merge. If anyone has further comments, please
speak up.
Thanks
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