On Thu, Jan 29, 2026 at 09:24:54PM +0000, David Matlack wrote: > Notify the PCI subsystem about devices vfio-pci is preserving across > Live Update by registering the vfio-pci liveupdate file handler with the > PCI subsystem's FLB handler. > > Notably this will ensure that devices preserved through vfio-pci will > have their PCI bus numbers preserved across Live Update, allowing VFIO > to use BDF as a key to identify the device across the Live Update and > (in the future) allow the device to continue DMA operations across > the Live Update. > > This also enables VFIO to detect that a device was preserved before > userspace first retrieves the file from it, which will be used in > subsequent commits. > > Signed-off-by: David Matlack <[email protected]> > --- > drivers/vfio/pci/vfio_pci_liveupdate.c | 25 ++++++++++++++++++++++++- > 1 file changed, 24 insertions(+), 1 deletion(-) > > diff --git a/drivers/vfio/pci/vfio_pci_liveupdate.c > b/drivers/vfio/pci/vfio_pci_liveupdate.c > index 7f4117181fd0..ad915352303f 100644 > --- a/drivers/vfio/pci/vfio_pci_liveupdate.c > +++ b/drivers/vfio/pci/vfio_pci_liveupdate.c > @@ -53,6 +53,8 @@ static int vfio_pci_liveupdate_preserve(struct > liveupdate_file_op_args *args) > if (IS_ERR(ser)) > return PTR_ERR(ser); > > + pci_liveupdate_outgoing_preserve(pdev); > + > ser->bdf = pci_dev_id(pdev); > ser->domain = pci_domain_nr(pdev->bus); > > @@ -62,6 +64,9 @@ static int vfio_pci_liveupdate_preserve(struct > liveupdate_file_op_args *args) > > static void vfio_pci_liveupdate_unpreserve(struct liveupdate_file_op_args > *args) > { > + struct vfio_device *device = vfio_device_from_file(args->file); > + > + pci_liveupdate_outgoing_unpreserve(to_pci_dev(device->dev)); > kho_unpreserve_free(phys_to_virt(args->serialized_data)); > } > > @@ -171,6 +176,9 @@ static bool vfio_pci_liveupdate_can_finish(struct > liveupdate_file_op_args *args) > > static void vfio_pci_liveupdate_finish(struct liveupdate_file_op_args *args) > { > + struct vfio_device *device = vfio_device_from_file(args->file); > + > + pci_liveupdate_incoming_finish(to_pci_dev(device->dev)); > kho_restore_free(phys_to_virt(args->serialized_data)); > } > > @@ -192,10 +200,24 @@ static struct liveupdate_file_handler > vfio_pci_liveupdate_fh = { > > int __init vfio_pci_liveupdate_init(void) > { > + int ret; > + > if (!liveupdate_enabled()) > return 0; > > - return liveupdate_register_file_handler(&vfio_pci_liveupdate_fh); > + ret = liveupdate_register_file_handler(&vfio_pci_liveupdate_fh); > + if (ret) > + return ret;
Nit: We might need to handle the retval here if we remove the liveupdate_enabled() check above (as discussed in patch 2). > + > + ret = pci_liveupdate_register_fh(&vfio_pci_liveupdate_fh); > + if (ret) > + goto error; > + > + return 0; > + > +error: > + liveupdate_unregister_file_handler(&vfio_pci_liveupdate_fh); > + return ret; > } > > void vfio_pci_liveupdate_cleanup(void) > @@ -203,5 +225,6 @@ void vfio_pci_liveupdate_cleanup(void) > if (!liveupdate_enabled()) > return; > > + WARN_ON_ONCE(pci_liveupdate_unregister_fh(&vfio_pci_liveupdate_fh)); same here. > liveupdate_unregister_file_handler(&vfio_pci_liveupdate_fh); > } Reviewed-by: Pranjal Shrivastava <[email protected]> Thanks, Praan
