[PATCH 2/4] vfio-pci/zdev: Pass the relaxed alignment flag

Matthew Rosato
2021-01-19T20:06:41Z

Use an additional bit of the VFIO_DEVICE_INFO_CAP_ZPCI_GROUP flags
field to pass whether or not the associated device supports relaxed
length and alignment for some I/O operations.

Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Acked-by: Niklas Schnelle <schnelle@linux.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
---
drivers/vfio/pci/vfio_pci_zdev.c | 2 ++
include/uapi/linux/vfio_zdev.h | 1 +
2 files changed, 3 insertions(+)

diff --git a/drivers/vfio/pci/vfio_pci_zdev.c b/drivers/vfio/pci/vfio_pci_zdev.c
index 2296856..57e19ff 100644
--- a/drivers/vfio/pci/vfio_pci_zdev.c
+++ b/drivers/vfio/pci/vfio_pci_zdev.c
@@ -60,6 +60,8 @@ static int zpci_group_cap(struct zpci_dev *zdev, struct vfio_pci_device *vdev,
.version = zdev->version
};

+ if (zdev->relaxed_align)
+ cap.flags |= VFIO_DEVICE_INFO_ZPCI_FLAG_RELAXED;
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 b430939..b0b6596 100644
--- a/include/uapi/linux/vfio_zdev.h
+++ b/include/uapi/linux/vfio_zdev.h
@@ -43,6 +43,7 @@ struct vfio_device_info_cap_zpci_group {
__u64 msi_addr; /* MSI address */
__u64 flags;
#define VFIO_DEVICE_INFO_ZPCI_FLAG_REFRESH 1 /* Program-specified TLB refresh */
+#define VFIO_DEVICE_INFO_ZPCI_FLAG_RELAXED 2 /* Relaxed Length and Alignment */
__u16 mui; /* Measurement Block Update Interval */
__u16 noi; /* Maximum number of MSIs */
__u16 maxstbl; /* Maximum Store Block Length */
--
1.8.3.1