Add a new migration capability 'mapped-ram'.
The core of the feature is to ensure that RAM pages are mapped
directly to offsets in the resulting migration file instead of being
streamed at arbitrary points.
The reasons why we'd want such behavior are:
- The resulting file will have a bounded size, since pages which are
dirtied multiple times will always go to a fixed location in the
file, rather than constantly being added to a sequential
stream. This eliminates cases where a VM with, say, 1G of RAM can
result in a migration file that's 10s of GBs, provided that the
workload constantly redirties memory.
- It paves the way to implement O_DIRECT-enabled save/restore of the
migration stream as the pages are ensured to be written at aligned
offsets.
- It allows the usage of multifd so we can write RAM pages to the
migration file in parallel.
For now, enabling the capability has no effect. The next couple of
patches implement the core functionality.
Acked-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240229153017.2221-8-farosas@suse.de
Signed-off-by: Peter Xu <peterx@redhat.com>
Some SuperI/O devices such as the VIA south bridges or the PC87312 controller
allow to enable or disable their SuperI/O functions. Add a convenience function
for implementing this in the VIA south bridges.
The naming of the functions is inspired by its memory_region_set_enabled()
pendant.
Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Message-Id: <20240114123911.4877-7-shentey@gmail.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Some SuperI/O devices such as the VIA south bridges or the PC87312 controller
are able to relocate their SuperI/O functions. Add a convenience function for
implementing this in the VIA south bridges.
This convenience function relies on previous simplifications in exec/ioport
which avoids some duplicate synchronization of I/O port base addresses. The
naming of the function is inspired by its memory_region_set_address() pendant.
Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Message-Id: <20240114123911.4877-6-shentey@gmail.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
