linux-kernel - [PATCH v6 3/3] vfio-cdx: add bus mastering device feature support

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Date:   Thu, 10 Aug 2023 14:14:09 +0530
From:   Nipun Gupta <nipun.gupta@....com>
To:     <gregkh@...uxfoundation.org>, <alex.williamson@...hat.com>,
        <linux-kernel@...r.kernel.org>
CC:     <git@....com>, <pieter.jansen-van-vuuren@....com>,
        <nikhil.agarwal@....com>, <michal.simek@....com>,
        <abhijit.gangurde@....com>, Nipun Gupta <nipun.gupta@....com>,
        Shubham Rohila <shubham.rohila@....com>
Subject: [PATCH v6 3/3] vfio-cdx: add bus mastering device feature support

Support Bus master enable and disable on VFIO-CDX devices using
VFIO_DEVICE_FEATURE_BUS_MASTER flag over VFIO_DEVICE_FEATURE IOCTL.

Co-developed-by: Shubham Rohila <shubham.rohila@....com>
Signed-off-by: Shubham Rohila <shubham.rohila@....com>
Signed-off-by: Nipun Gupta <nipun.gupta@....com>
---

Changes v5->v6:
- Called CDX device reset at cdx_open_device()

Changes v4->v5:
- Use device feature IOCTL instead of adding a new VFIO IOCTL
  for bus master feature.

Changes in v4:
- This patch is newly added which uses cdx_set_master() and
  cdx_clear_master() APIs.

 drivers/vfio/cdx/main.c | 46 +++++++++++++++++++++++++++++++++++++++--
 1 file changed, 44 insertions(+), 2 deletions(-)

diff --git a/drivers/vfio/cdx/main.c b/drivers/vfio/cdx/main.c
index c376a69d2db2..bf0e1f56e0f9 100644
--- a/drivers/vfio/cdx/main.c
+++ b/drivers/vfio/cdx/main.c
@@ -14,7 +14,7 @@ static int vfio_cdx_open_device(struct vfio_device *core_vdev)
 		container_of(core_vdev, struct vfio_cdx_device, vdev);
 	struct cdx_device *cdx_dev = to_cdx_device(core_vdev->dev);
 	int count = cdx_dev->res_count;
-	int i;
+	int i, ret;
 
 	vdev->regions = kcalloc(count, sizeof(struct vfio_cdx_region),
 				GFP_KERNEL_ACCOUNT);
@@ -39,8 +39,11 @@ static int vfio_cdx_open_device(struct vfio_device *core_vdev)
 		if (!(cdx_dev->res[i].flags & IORESOURCE_READONLY))
 			vdev->regions[i].flags |= VFIO_REGION_INFO_FLAG_WRITE;
 	}
+	ret = cdx_dev_reset(core_vdev->dev);
+	if (ret)
+		kfree(vdev->regions);
 
-	return 0;
+	return ret;
 }
 
 static void vfio_cdx_close_device(struct vfio_device *core_vdev)
@@ -52,6 +55,44 @@ static void vfio_cdx_close_device(struct vfio_device *core_vdev)
 	cdx_dev_reset(core_vdev->dev);
 }
 
+static int vfio_cdx_bm_ctrl(struct vfio_device *core_vdev, u32 flags,
+			    void __user *arg, size_t argsz)
+{
+	size_t minsz =
+		offsetofend(struct vfio_device_feature_bus_master, op);
+	struct cdx_device *cdx_dev = to_cdx_device(core_vdev->dev);
+	struct vfio_device_feature_bus_master ops;
+	int ret;
+
+	ret = vfio_check_feature(flags, argsz, VFIO_DEVICE_FEATURE_SET,
+				 sizeof(ops));
+	if (ret != 1)
+		return ret;
+
+	if (copy_from_user(&ops, arg, minsz))
+		return -EFAULT;
+
+	switch (ops.op) {
+	case VFIO_DEVICE_FEATURE_CLEAR_MASTER:
+		return cdx_clear_master(cdx_dev);
+	case VFIO_DEVICE_FEATURE_SET_MASTER:
+		return cdx_set_master(cdx_dev);
+	default:
+		return -EINVAL;
+	}
+}
+
+static int vfio_cdx_ioctl_feature(struct vfio_device *device, u32 flags,
+				  void __user *arg, size_t argsz)
+{
+	switch (flags & VFIO_DEVICE_FEATURE_MASK) {
+	case VFIO_DEVICE_FEATURE_BUS_MASTER:
+		return vfio_cdx_bm_ctrl(device, flags, arg, argsz);
+	default:
+		return -ENOTTY;
+	}
+}
+
 static int vfio_cdx_ioctl_get_info(struct vfio_cdx_device *vdev,
 				   struct vfio_device_info __user *arg)
 {
@@ -169,6 +210,7 @@ static const struct vfio_device_ops vfio_cdx_ops = {
 	.open_device	= vfio_cdx_open_device,
 	.close_device	= vfio_cdx_close_device,
 	.ioctl		= vfio_cdx_ioctl,
+	.device_feature = vfio_cdx_ioctl_feature,
 	.mmap		= vfio_cdx_mmap,
 	.bind_iommufd	= vfio_iommufd_physical_bind,
 	.unbind_iommufd	= vfio_iommufd_physical_unbind,
-- 
2.17.1