vfio-pci/zdev: different maxstbl for interpreted devices

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.

Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Link: https://lore.kernel.org/r/20220606203325.110625-20-mjrosato@linux.ibm.com
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>

diff --git a/drivers/vfio/pci/vfio_pci_zdev.c b/drivers/vfio/pci/vfio_pci_zdev.c
index 4f28cdd7ecd1c41bfbdce848da4e2d02a8c7342f..e163aa9f61444f7b6ead297f7149f478772196d0 100644 (file)
--- a/drivers/vfio/pci/vfio_pci_zdev.c
+++ b/drivers/vfio/pci/vfio_pci_zdev.c
@@ -45,14 +45,16 @@ 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 78c022af3d29acaf1dce4ce5a13d99f64f5d5754..77f2aff1f27e9310118dc6492ed14e90b6d2bf55 100644 (file)
--- 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 */
 };
 
 /**