Re: [RFC PATCH 3/9] vfio/pci: register a default migration region

Yan Zhao
2019-12-06T05:59:10Z

On Fri, Dec 06, 2019 at 07:55:15AM +0800, Alex Williamson wrote:
> On Wed, 4 Dec 2019 22:26:38 -0500
> Yan Zhao <yan.y.zhao@intel.com> wrote:
>
> > Vendor driver specifies when to support a migration region through cap
> > VFIO_PCI_DEVICE_CAP_MIGRATION in vfio_pci_mediate_ops->open().
> >
> > If vfio-pci detects this cap, it creates a default migration region on
> > behalf of vendor driver with region len=0 and region->ops=null.
> > Vendor driver should override this region's len, flags, rw, mmap in
> > its vfio_pci_mediate_ops.
> >
> > This migration region definition is aligned to QEMU vfio migration code v8:
> > (https://lists.gnu.org/archive/html/qemu-devel/2019-08/msg05542.html)
> >
> > Cc: Kevin Tian <kevin.tian@intel.com>
> >
> > Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
> > ---
> > drivers/vfio/pci/vfio_pci.c | 15 ++++
> > include/linux/vfio.h | 1 +
> > include/uapi/linux/vfio.h | 149 ++++++++++++++++++++++++++++++++++++
> > 3 files changed, 165 insertions(+)
> >
> > diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> > index f3730252ee82..059660328be2 100644
> > --- a/drivers/vfio/pci/vfio_pci.c
> > +++ b/drivers/vfio/pci/vfio_pci.c
> > @@ -115,6 +115,18 @@ static inline bool vfio_pci_is_vga(struct pci_dev *pdev)
> > return (pdev->class >> 8) == PCI_CLASS_DISPLAY_VGA;
> > }
> >
> > +/**
> > + * init a region to hold migration ctl & data
> > + */
> > +void init_migration_region(struct vfio_pci_device *vdev)
> > +{
> > + vfio_pci_register_dev_region(vdev, VFIO_REGION_TYPE_MIGRATION,
> > + VFIO_REGION_SUBTYPE_MIGRATION,
> > + NULL, 0,
> > + VFIO_REGION_INFO_FLAG_READ | VFIO_REGION_INFO_FLAG_WRITE,
> > + NULL);
> > +}
> > +
> > static void vfio_pci_probe_mmaps(struct vfio_pci_device *vdev)
> > {
> > struct resource *res;
> > @@ -523,6 +535,9 @@ static int vfio_pci_open(void *device_data)
> > vdev->mediate_ops = mentry->ops;
> > vdev->mediate_handle = handle;
> >
> > + if (caps & VFIO_PCI_DEVICE_CAP_MIGRATION)
> > + init_migration_region(vdev);
>
> No. We're not going to add a cap flag for every region the mediation
> driver wants to add. The mediation driver should have the ability to
> add regions and irqs to the device itself. Thanks,
>
> Alex
>
ok. got it. will do it.

Thanks
Yan

> > +
> > pr_info("vfio pci found mediate_ops %s, caps=%llx, handle=%x for %x:%x\n",
> > vdev->mediate_ops->name, caps,
> > handle, vdev->pdev->vendor,
>