motorhead/qemu
1
0
Fork 0
mirror of https://github.com/Motorhead1991/qemu.git synced 2025-08-08 18:23:57 -06:00
Code Issues Projects Releases Packages Wiki Activity Actions

virtio-mem: Migrate immutable properties early

Browse source 
The bitmap and the size are immutable while migration is active: see
virtio_mem_is_busy(). We can migrate this information early, before
migrating any actual RAM content. Further, all information we need for
sanity checks is immutable as well.

Having this information in place early will, for example, allow for
properly preallocating memory before touching these memory locations
during RAM migration: this way, we can make sure that all memory was
actually preallocated and that any user errors (e.g., insufficient
hugetlb pages) can be handled gracefully.

In contrast, usable_region_size and requested_size can theoretically
still be modified on the source while the VM is running. Keep migrating
these properties the usual, late, way.

Use a new device property to keep behavior of compat machines
unmodified.

Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>S
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
This commit is contained in:
David Hildenbrand 2023-01-17 12:22:48 +01:00 • committed by Juan Quintela
parent ce1761f0f9
commit 3b95a71b22
3 changed files with 60 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files

51
hw/virtio/virtio-mem.c
View file

@ -31,6 +31,8 @@
#include CONFIG_DEVICES
#include "trace.h"
static const VMStateDescription vmstate_virtio_mem_device_early;
/*
* We only had legacy x86 guests that did not support
* VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE. Other targets don't have legacy guests.
@ -878,6 +880,10 @@ static void virtio_mem_device_realize(DeviceState *dev, Error **errp)
host_memory_backend_set_mapped(vmem->memdev, true);
vmstate_register_ram(&vmem->memdev->mr, DEVICE(vmem));
if (vmem->early_migration) {
vmstate_register(VMSTATE_IF(vmem), VMSTATE_INSTANCE_ID_ANY,
&vmstate_virtio_mem_device_early, vmem);
}
qemu_register_reset(virtio_mem_system_reset, vmem);
/*
@ -899,6 +905,10 @@ static void virtio_mem_device_unrealize(DeviceState *dev)
*/
memory_region_set_ram_discard_manager(&vmem->memdev->mr, NULL);
qemu_unregister_reset(virtio_mem_system_reset, vmem);
if (vmem->early_migration) {
vmstate_unregister(VMSTATE_IF(vmem), &vmstate_virtio_mem_device_early,
vmem);
}
vmstate_unregister_ram(&vmem->memdev->mr, DEVICE(vmem));
host_memory_backend_set_mapped(vmem->memdev, false);
virtio_del_queue(vdev, 0);
@ -1015,18 +1025,53 @@ static const VMStateDescription vmstate_virtio_mem_sanity_checks = {
},
};
static bool virtio_mem_vmstate_field_exists(void *opaque, int version_id)
{
const VirtIOMEM *vmem = VIRTIO_MEM(opaque);
/* With early migration, these fields were already migrated. */
return !vmem->early_migration;
}
static const VMStateDescription vmstate_virtio_mem_device = {
.name = "virtio-mem-device",
.minimum_version_id = 1,
.version_id = 1,
.priority = MIG_PRI_VIRTIO_MEM,
.post_load = virtio_mem_post_load,
.fields = (VMStateField[]) {
VMSTATE_WITH_TMP_TEST(VirtIOMEM, virtio_mem_vmstate_field_exists,
VirtIOMEMMigSanityChecks,
vmstate_virtio_mem_sanity_checks),
VMSTATE_UINT64(usable_region_size, VirtIOMEM),
VMSTATE_UINT64_TEST(size, VirtIOMEM, virtio_mem_vmstate_field_exists),
VMSTATE_UINT64(requested_size, VirtIOMEM),
VMSTATE_BITMAP_TEST(bitmap, VirtIOMEM, virtio_mem_vmstate_field_exists,
0, bitmap_size),
VMSTATE_END_OF_LIST()
},
};
/*
* Transfer properties that are immutable while migration is active early,
* such that we have have this information around before migrating any RAM
* content.
*
* Note that virtio_mem_is_busy() makes sure these properties can no longer
* change on the migration source until migration completed.
*
* With QEMU compat machines, we transmit these properties later, via
* vmstate_virtio_mem_device instead -- see virtio_mem_vmstate_field_exists().
*/
static const VMStateDescription vmstate_virtio_mem_device_early = {
.name = "virtio-mem-device-early",
.minimum_version_id = 1,
.version_id = 1,
.early_setup = true,
.fields = (VMStateField[]) {
VMSTATE_WITH_TMP(VirtIOMEM, VirtIOMEMMigSanityChecks,
vmstate_virtio_mem_sanity_checks),
VMSTATE_UINT64(usable_region_size, VirtIOMEM),
VMSTATE_UINT64(size, VirtIOMEM),
VMSTATE_UINT64(requested_size, VirtIOMEM),
VMSTATE_BITMAP(bitmap, VirtIOMEM, 0, bitmap_size),
VMSTATE_END_OF_LIST()
},
@ -1211,6 +1256,8 @@ static Property virtio_mem_properties[] = {
DEFINE_PROP_ON_OFF_AUTO(VIRTIO_MEM_UNPLUGGED_INACCESSIBLE_PROP, VirtIOMEM,
unplugged_inaccessible, ON_OFF_AUTO_AUTO),
#endif
DEFINE_PROP_BOOL(VIRTIO_MEM_EARLY_MIGRATION_PROP, VirtIOMEM,
early_migration, true),
DEFINE_PROP_END_OF_LIST(),
};