[PATCH v6 18/21] vfio-pci/zdev: different maxstbl for interpreted devices

From: Matthew Rosato <mjrosato@linux.ibm.com>
To: linux-s390@vger.kernel.org
Cc: alex.williamson@redhat.com, cohuck@redhat.com,
	schnelle@linux.ibm.com, farman@linux.ibm.com,
	pmorel@linux.ibm.com, borntraeger@linux.ibm.com,
	hca@linux.ibm.com, gor@linux.ibm.com,
	gerald.schaefer@linux.ibm.com, agordeev@linux.ibm.com,
	svens@linux.ibm.com, frankja@linux.ibm.com, david@redhat.com,
	imbrenda@linux.ibm.com, vneethv@linux.ibm.com,
	oberpar@linux.ibm.com, freude@linux.ibm.com, thuth@redhat.com,
	pasic@linux.ibm.com, pbonzini@redhat.com, corbet@lwn.net,
	jgg@nvidia.com, kvm@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org
Subject: [PATCH v6 18/21] vfio-pci/zdev: different maxstbl for interpreted devices
Date: Tue, 26 Apr 2022 16:08:39 -0400	[thread overview]
Message-ID: <20220426200842.98655-19-mjrosato@linux.ibm.com> (raw)
In-Reply-To: <20220426200842.98655-1-mjrosato@linux.ibm.com>

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>
---
 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 00183e8aa393..ea20d4d36eef 100644
--- 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 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 */
 };
 
 /**
-- 
2.27.0

