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Re: [PATCH v2 00/11] vfio/migration: Implement VFIO migration protocol v
From: |
Alex Williamson |
Subject: |
Re: [PATCH v2 00/11] vfio/migration: Implement VFIO migration protocol v2 |
Date: |
Tue, 7 Jun 2022 15:32:39 -0600 |
On Tue, 7 Jun 2022 20:44:23 +0300
Avihai Horon <avihaih@nvidia.com> wrote:
> On 5/30/2022 8:07 PM, Avihai Horon wrote:
> > Hello,
> >
> > Following VFIO migration protocol v2 acceptance in kernel, this series
> > implements VFIO migration according to the new v2 protocol and replaces
> > the now deprecated v1 implementation.
> >
> > The main differences between v1 and v2 migration protocols are:
> > 1. VFIO device state is represented as a finite state machine instead of
> > a bitmap.
> >
> > 2. The migration interface with kernel is done using VFIO_DEVICE_FEATURE
> > ioctl and normal read() and write() instead of the migration region
> > used in v1.
> >
> > 3. Migration protocol v2 currently doesn't support the pre-copy phase of
> > migration.
> >
> > Full description of the v2 protocol and the differences from v1 can be
> > found here [1].
> >
> > Patches 1-3 are prep patches fixing bugs and adding QEMUFile function
> > that will be used later.
> >
> > Patches 4-6 refactor v1 protocol code to make it easier to add v2
> > protocol.
> >
> > Patches 7-11 implement v2 protocol and remove v1 protocol.
> >
> > Thanks.
> >
> > [1]
> > https://lore.kernel.org/all/20220224142024.147653-10-yishaih@nvidia.com/
> >
> > Changes from v1:
> > https://lore.kernel.org/all/20220512154320.19697-1-avihaih@nvidia.com/
> > - Split the big patch that replaced v1 with v2 into several patches as
> > suggested by Joao, to make review easier.
> > - Change warn_report to warn_report_once when container doesn't support
> > dirty tracking.
> > - Add Reviewed-by tag.
> >
> > Avihai Horon (11):
> > vfio/migration: Fix NULL pointer dereference bug
> > vfio/migration: Skip pre-copy if dirty page tracking is not supported
> > migration/qemu-file: Add qemu_file_get_to_fd()
> > vfio/common: Change vfio_devices_all_running_and_saving() logic to
> > equivalent one
> > vfio/migration: Move migration v1 logic to vfio_migration_init()
> > vfio/migration: Rename functions/structs related to v1 protocol
> > vfio/migration: Implement VFIO migration protocol v2
> > vfio/migration: Remove VFIO migration protocol v1
> > vfio/migration: Reset device if setting recover state fails
> > vfio: Alphabetize migration section of VFIO trace-events file
> > docs/devel: Align vfio-migration docs to VFIO migration v2
> >
> > docs/devel/vfio-migration.rst | 77 ++--
> > hw/vfio/common.c | 21 +-
> > hw/vfio/migration.c | 640 ++++++++--------------------------
> > hw/vfio/trace-events | 25 +-
> > include/hw/vfio/vfio-common.h | 8 +-
> > migration/migration.c | 5 +
> > migration/migration.h | 3 +
> > migration/qemu-file.c | 34 ++
> > migration/qemu-file.h | 1 +
> > 9 files changed, 252 insertions(+), 562 deletions(-)
> >
> Ping.
Based on the changelog, this seems like a mostly cosmetic spin and I
don't see that all of the discussion threads from v1 were resolved to
everyone's satisfaction. I'm certainly still uncomfortable with the
pre-copy behavior and I thought there were still some action items to
figure out whether an SLA is present and vet the solution with
management tools. Thanks,
Alex