migration/ram: Introduce 'mapped-ram' migration capability

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 res

migration/ram: Introduce 'mapped-ram' migration capability

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>

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docs/devel/migration.rst: Document the file transport

When adding the support for file migration with the file: transport,
we missed adding documentation for it.

Signed-off-by: Fabiano Rosas <faros

docs/devel/migration.rst: Document the file transport

When adding the support for file migration with the file: transport,
we missed adding documentation for it.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/20240220224138.24759-2-farosas@suse.de
Signed-off-by: Peter Xu <peterx@redhat.com>

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exec/ioport: Add portio_list_set_enabled()

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 functi

exec/ioport: Add portio_list_set_enabled()

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>

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exec/ioport: Add portio_list_set_address()

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

exec/ioport: Add portio_list_set_address()

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>

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docs/migration: Further move virtio to be feature of migration

Move it one layer down, so taking Virtio-migration as a feature for
migration.

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wan

docs/migration: Further move virtio to be feature of migration

Move it one layer down, so taking Virtio-migration as a feature for
migration.

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/r/20240109064628.595453-11-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>

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docs/migration: Further move vfio to be feature of migration

Move it one layer down, so taking VFIO-migration as a feature for
migration.

Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Cédric

docs/migration: Further move vfio to be feature of migration

Move it one layer down, so taking VFIO-migration as a feature for
migration.

Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/r/20240109064628.595453-10-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>

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docs/migration: Organize "Postcopy" page

Reorganize the page, moving things around, and add a few
headlines ("Postcopy internals", "Postcopy features") to cover sub-areas.

Reviewed-by: Cédric Le Go

docs/migration: Organize "Postcopy" page

Reorganize the page, moving things around, and add a few
headlines ("Postcopy internals", "Postcopy features") to cover sub-areas.

Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/r/20240109064628.595453-9-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>

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docs/migration: Split "dirty limit"

Split that into a separate file, put under "features".

Cc: Yong Huang <yong.huang@smartx.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.k

docs/migration: Split "dirty limit"

Split that into a separate file, put under "features".

Cc: Yong Huang <yong.huang@smartx.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/r/20240109064628.595453-8-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>

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docs/migration: Split "Postcopy"

Split postcopy into a separate file. Introduce a head page "features.rst"
to keep all the features on top of migration framework.

Reviewed-by: Cédric Le Goater <cl

docs/migration: Split "Postcopy"

Split postcopy into a separate file. Introduce a head page "features.rst"
to keep all the features on top of migration framework.

Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/r/20240109064628.595453-7-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>

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docs/migration: Split "Debugging" and "Firmware"

Move the two sections into a separate file called "best-practices.rst".
Add the entry into index.

Reviewed-by: Cédric Le Goater <clg@redhat.com>
Lin

docs/migration: Split "Debugging" and "Firmware"

Move the two sections into a separate file called "best-practices.rst".
Add the entry into index.

Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/r/20240109064628.595453-6-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>

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docs/migration: Split "Backwards compatibility" separately

Split the section from main.rst into a separate file. Reference it in the
index.rst.

Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link:

docs/migration: Split "Backwards compatibility" separately

Split the section from main.rst into a separate file. Reference it in the
index.rst.

Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/r/20240109064628.595453-5-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>

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docs/migration: Convert virtio.txt into rST

Convert the plain old .txt into .rst, add it into migration/index.rst.

Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/r/202

docs/migration: Convert virtio.txt into rST

Convert the plain old .txt into .rst, add it into migration/index.rst.

Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/r/20240109064628.595453-4-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>

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docs/migration: Create index page

Create an index page for migration module. Move VFIO migration there too.
A trivial touch-up on the title to use lower case there.

Since then we'll have "migratio

docs/migration: Create index page

Create an index page for migration module. Move VFIO migration there too.
A trivial touch-up on the title to use lower case there.

Since then we'll have "migration" as the top title, make the main doc file
renamed to "migration framework".

Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/r/20240109064628.595453-3-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>

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docs/migration: Create migration/ directory

Migration documentation is growing into a single file too large. Create a
sub-directory for it for a split.

We also already have separate vfio/virtio do

docs/migration: Create migration/ directory

Migration documentation is growing into a single file too large. Create a
sub-directory for it for a split.

We also already have separate vfio/virtio documentations, move it all over
into the directory.

Note that the virtio one is still not yet converted to rST. That is a job
for later.

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/r/20240109064628.595453-2-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>

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