Re: [PATCH v5 18/21] vfio-pci/zdev: different maxstbl for interpreted devices

Pierre Morel
2022-04-19T09:38:40Z

On 4/4/22 19:43, Matthew Rosato wrote:
> When doing load/store interpretation, the maximum store block length is
> determined by the underlying firmware, not the host kernel API. Reflect
> that in the associated Query PCI Function Group clp capability and let
> userspace decide which is appropriate to present to the guest.
>
> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>

Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>

> ---
> drivers/vfio/pci/vfio_pci_zdev.c | 6 ++++--
> include/uapi/linux/vfio_zdev.h | 4 ++++
> 2 files changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/vfio/pci/vfio_pci_zdev.c b/drivers/vfio/pci/vfio_pci_zdev.c
> index 4a653ce480c7..d3ca58d9d8ec 100644
> --- a/drivers/vfio/pci/vfio_pci_zdev.c
> +++ b/drivers/vfio/pci/vfio_pci_zdev.c
> @@ -44,14 +44,16 @@ static int zpci_group_cap(struct zpci_dev *zdev, struct vfio_info_cap *caps)
> {
> struct vfio_device_info_cap_zpci_group cap = {
> .header.id = VFIO_DEVICE_INFO_CAP_ZPCI_GROUP,
> - .header.version = 1,
> + .header.version = 2,
> .dasm = zdev->dma_mask,
> .msi_addr = zdev->msi_addr,
> .flags = VFIO_DEVICE_INFO_ZPCI_FLAG_REFRESH,
> .mui = zdev->fmb_update,
> .noi = zdev->max_msi,
> .maxstbl = ZPCI_MAX_WRITE_SIZE,
> - .version = zdev->version
> + .version = zdev->version,
> + .reserved = 0,
> + .imaxstbl = zdev->maxstbl
> };
>
> return vfio_info_add_capability(caps, &cap.header, sizeof(cap));
> diff --git a/include/uapi/linux/vfio_zdev.h b/include/uapi/linux/vfio_zdev.h
> index 78c022af3d29..77f2aff1f27e 100644
> --- a/include/uapi/linux/vfio_zdev.h
> +++ b/include/uapi/linux/vfio_zdev.h
> @@ -50,6 +50,10 @@ struct vfio_device_info_cap_zpci_group {
> __u16 noi; /* Maximum number of MSIs */
> __u16 maxstbl; /* Maximum Store Block Length */
> __u8 version; /* Supported PCI Version */
> + /* End of version 1 */
> + __u8 reserved;
> + __u16 imaxstbl; /* Maximum Interpreted Store Block Length */
> + /* End of version 2 */
> };
>
> /**
>

--
Pierre Morel
IBM Lab Boeblingen