When try to do the vfio post-copy migration, we can get an expected internal error now: "unable to execute QEMU command 'migrate': 0000:b1:00.2: VFIO migration is not supported with postcopy migration"
Tested-by: Yanghang Liu <yangh...@redhat.com> Best Regards, YangHang Liu On Thu, Aug 31, 2023 at 8:57 PM Avihai Horon <avih...@nvidia.com> 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 <yangh...@redhat.com> > Signed-off-by: Avihai Horon <avih...@nvidia.com> > --- > hw/vfio/migration.c | 22 ++++++++++++++++++++++ > 1 file changed, 22 insertions(+) > > 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, > -- > 2.26.3 >