| Message ID | 20230906150853.22176-6-avihaih@nvidia.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | vfio/migration: Block VFIO migration with postcopy and background snapshot | expand |
On Wed, Sep 06, 2023 at 06:08:52PM +0300, Avihai Horon wrote: > VFIO migration is not compatible with postcopy migration. A VFIO device > in the destination can't handle page faults for pages that have not been > sent yet. > > Doing such migration will cause the VM to crash in the destination: > > qemu-system-x86_64: VFIO_MAP_DMA failed: Bad address > qemu-system-x86_64: vfio_dma_map(0x55a28c7659d0, 0xc0000, 0xb000, 0x7f1b11a00000) = -14 (Bad address) > qemu: hardware error: vfio: DMA mapping failed, unable to continue > > To prevent this, block VFIO migration with postcopy migration. > > Reported-by: Yanghang Liu <yanghliu@redhat.com> > Signed-off-by: Avihai Horon <avihaih@nvidia.com> > Tested-by: Yanghang Liu <yanghliu@redhat.com> Reviewed-by: Peter Xu <peterx@redhat.com>
diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c index 71855468fe..20994dc1d6 100644 --- a/hw/vfio/migration.c +++ b/hw/vfio/migration.c @@ -335,6 +335,27 @@ static bool vfio_precopy_supported(VFIODevice *vbasedev) /* ---------------------------------------------------------------------- */ +static int vfio_save_prepare(void *opaque, Error **errp) +{ + VFIODevice *vbasedev = opaque; + + /* + * Snapshot doesn't use postcopy, so allow snapshot even if postcopy is on. + */ + if (runstate_check(RUN_STATE_SAVE_VM)) { + return 0; + } + + if (migrate_postcopy_ram()) { + error_setg( + errp, "%s: VFIO migration is not supported with postcopy migration", + vbasedev->name); + return -EOPNOTSUPP; + } + + return 0; +} + static int vfio_save_setup(QEMUFile *f, void *opaque) { VFIODevice *vbasedev = opaque; @@ -640,6 +661,7 @@ static bool vfio_switchover_ack_needed(void *opaque) } static const SaveVMHandlers savevm_vfio_handlers = { + .save_prepare = vfio_save_prepare, .save_setup = vfio_save_setup, .save_cleanup = vfio_save_cleanup, .state_pending_estimate = vfio_state_pending_estimate,