[PATCH v2 2/2] bus/cdx: add bus master enable/disable APIs

[Shubham Rohila <shubham.rohila@amd.com>]

Define rte_cdx_vfio_bm_enable and rte_cdx_vfio_bm_disable to
enable or disable bus master functionality for cdx devices.

Signed-off-by: Shubham Rohila <shubham.rohila@amd.com>
---
 v2
 - Fix indentations and alphabetical orderings.
 - Wrap checks in parenthesis for readability
 - Assign argsz before using in rte_cdx_vfio_bm_disable
 - Remove unecessary variable initialisation

 drivers/bus/cdx/bus_cdx_driver.h |  25 ++++++++
 drivers/bus/cdx/cdx_vfio.c       | 103 +++++++++++++++++++++++++++++++
 drivers/bus/cdx/version.map      |   2 +
 lib/eal/include/rte_vfio.h       |  27 ++++++++
 4 files changed, 157 insertions(+)

diff --git a/drivers/bus/cdx/bus_cdx_driver.h b/drivers/bus/cdx/bus_cdx_driver.h
index 1c9a64c87a..211f8e406b 100644
--- a/drivers/bus/cdx/bus_cdx_driver.h
+++ b/drivers/bus/cdx/bus_cdx_driver.h
@@ -16,6 +16,7 @@ extern "C" {
 
 #include <stdlib.h>
 #include <inttypes.h>
+#include <linux/types.h>
 
 #include <bus_driver.h>
 #include <dev_driver.h>
@@ -178,6 +179,30 @@ int rte_cdx_vfio_intr_enable(const struct rte_intr_handle *intr_handle);
 __rte_internal
 int rte_cdx_vfio_intr_disable(const struct rte_intr_handle *intr_handle);
 
+/**
+ * Enable Bus Mastering for CDX bus devices.
+ *
+ * @param dev
+ *   Pointer to the cdx device.
+ *
+ * @return
+ *   0 on success, -1 on error.
+ */
+__rte_internal
+int rte_cdx_vfio_bm_enable(struct rte_cdx_device *dev);
+
+/**
+ * Disable Bus Mastering for CDX bus devices.
+ *
+ * @param dev
+ *   Pointer to the cdx device.
+ *
+ * @return
+ *   0 on success, -1 on error.
+ */
+__rte_internal
+int rte_cdx_vfio_bm_disable(struct rte_cdx_device *dev);
+
 /**
  * Unregister a CDX driver.
  *
diff --git a/drivers/bus/cdx/cdx_vfio.c b/drivers/bus/cdx/cdx_vfio.c
index 8cac79782e..1481022f13 100644
--- a/drivers/bus/cdx/cdx_vfio.c
+++ b/drivers/bus/cdx/cdx_vfio.c
@@ -102,6 +102,10 @@ cdx_vfio_unmap_resource_primary(struct rte_cdx_device *dev)
 	int ret, vfio_dev_fd;
 
 	if (rte_intr_fd_get(dev->intr_handle) >= 0) {
+		if (rte_cdx_vfio_bm_disable(dev) < 0)
+			CDX_BUS_ERR("Error when disabling bus master for %s",
+				    dev->device.name);
+
 		if (close(rte_intr_fd_get(dev->intr_handle)) < 0) {
 			CDX_BUS_ERR("Error when closing eventfd file descriptor for %s",
 				dev->device.name);
@@ -255,6 +259,16 @@ cdx_vfio_setup_device(struct rte_cdx_device *dev, int vfio_dev_fd,
 		return -1;
 	}
 
+	/*
+	 * Enable Bus mastering for the device. errno is set as ENOTTY if
+	 * device does not support configuring bus master.
+	 */
+	if (rte_cdx_vfio_bm_enable(dev) && (errno != -ENOTTY)) {
+		CDX_BUS_ERR("Bus master enable failure! Error: %d (%s)", errno,
+			strerror(errno));
+		return -1;
+	}
+
 	return 0;
 }
 
@@ -595,3 +609,92 @@ rte_cdx_vfio_intr_disable(const struct rte_intr_handle *intr_handle)
 
 	return ret;
 }
+
+/* enable Bus Mastering */
+int
+rte_cdx_vfio_bm_enable(struct rte_cdx_device *dev)
+{
+	struct vfio_device_info device_info = { .argsz = sizeof(device_info) };
+	struct vfio_device_feature_bus_master *vfio_bm_feature;
+	struct vfio_device_feature *feature;
+	int vfio_dev_fd, ret;
+	size_t argsz;
+
+	vfio_dev_fd = rte_intr_dev_fd_get(dev->intr_handle);
+	if (vfio_dev_fd < 0)
+		return -1;
+
+	argsz = sizeof(struct vfio_device_feature) + sizeof(struct vfio_device_feature_bus_master);
+
+	feature = (struct vfio_device_feature *)malloc(argsz);
+	if (!feature)
+		return -ENOMEM;
+
+	vfio_bm_feature = (struct vfio_device_feature_bus_master *) feature->data;
+
+	feature->argsz = argsz;
+
+	feature->flags = RTE_VFIO_DEVICE_FEATURE_BUS_MASTER | VFIO_DEVICE_FEATURE_PROBE;
+	feature->flags |= VFIO_DEVICE_FEATURE_SET;
+	ret = ioctl(vfio_dev_fd, RTE_VFIO_DEVICE_FEATURE, feature);
+	if (ret) {
+		CDX_BUS_ERR("Bus Master configuring not supported for device: %s, error: %d (%s)\n",
+			dev->name, errno, strerror(errno));
+		free(feature);
+		return ret;
+	}
+
+	feature->flags = RTE_VFIO_DEVICE_FEATURE_BUS_MASTER | VFIO_DEVICE_FEATURE_SET;
+	vfio_bm_feature->op = VFIO_DEVICE_FEATURE_SET_MASTER;
+	ret = ioctl(vfio_dev_fd, RTE_VFIO_DEVICE_FEATURE, feature);
+	if (ret < 0)
+		CDX_BUS_ERR("BM Enable Error for device: %s, Error: %d (%s)\n",
+			dev->name, errno, strerror(errno));
+
+	free(feature);
+	return ret;
+}
+
+/* Disable Bus Mastering */
+int
+rte_cdx_vfio_bm_disable(struct rte_cdx_device *dev)
+{
+	struct vfio_device_feature_bus_master *vfio_bm_feature;
+	struct vfio_device_feature *feature;
+	int vfio_dev_fd, ret;
+	size_t argsz;
+
+	vfio_dev_fd = rte_intr_dev_fd_get(dev->intr_handle);
+	if (vfio_dev_fd < 0)
+		return -1;
+
+	argsz = sizeof(struct vfio_device_feature) + sizeof(struct vfio_device_feature_bus_master);
+
+	feature = (struct vfio_device_feature *)malloc(argsz);
+	if (!feature)
+		return -ENOMEM;
+
+	vfio_bm_feature = (struct vfio_device_feature_bus_master *) feature->data;
+
+	feature->argsz = argsz;
+
+	feature->flags = RTE_VFIO_DEVICE_FEATURE_BUS_MASTER | VFIO_DEVICE_FEATURE_PROBE;
+	feature->flags |= VFIO_DEVICE_FEATURE_SET;
+	ret = ioctl(vfio_dev_fd, RTE_VFIO_DEVICE_FEATURE, feature);
+	if (ret) {
+		CDX_BUS_ERR("Bus Master configuring not supported for device: %s, Error: %d (%s)\n",
+			dev->name, errno, strerror(errno));
+		free(feature);
+		return ret;
+	}
+
+	feature->flags = RTE_VFIO_DEVICE_FEATURE_BUS_MASTER | VFIO_DEVICE_FEATURE_SET;
+	vfio_bm_feature->op = VFIO_DEVICE_FEATURE_CLEAR_MASTER;
+	ret = ioctl(vfio_dev_fd, RTE_VFIO_DEVICE_FEATURE, feature);
+	if (ret < 0)
+		CDX_BUS_ERR("BM Disable Error for device: %s, Error: %d (%s)\n",
+			dev->name, errno, strerror(errno));
+
+	free(feature);
+	return ret;
+}
diff --git a/drivers/bus/cdx/version.map b/drivers/bus/cdx/version.map
index 0a15d39ae8..7a22cf5b4b 100644
--- a/drivers/bus/cdx/version.map
+++ b/drivers/bus/cdx/version.map
@@ -5,6 +5,8 @@ INTERNAL {
 	rte_cdx_register;
 	rte_cdx_unmap_device;
 	rte_cdx_unregister;
+	rte_cdx_vfio_bm_disable;
+	rte_cdx_vfio_bm_enable;
 	rte_cdx_vfio_intr_disable;
 	rte_cdx_vfio_intr_enable;
 
diff --git a/lib/eal/include/rte_vfio.h b/lib/eal/include/rte_vfio.h
index 3487c4f2a2..22832afd0f 100644
--- a/lib/eal/include/rte_vfio.h
+++ b/lib/eal/include/rte_vfio.h
@@ -73,6 +73,33 @@ struct vfio_info_cap_header {
 #define RTE_VFIO_CAP_MSIX_MAPPABLE 3
 #endif
 
+/* VFIO_DEVICE_FEATURE is defined for kernel version 5.7 and newer. */
+#ifdef	VFIO_DEVICE_FEATURE
+#define	RTE_VFIO_DEVICE_FEATURE	VFIO_DEVICE_FEATURE
+#else
+#define	RTE_VFIO_DEVICE_FEATURE	_IO(VFIO_TYPE, VFIO_BASE + 17)
+struct vfio_device_feature {
+	__u32	argsz;
+	__u32	flags;
+#define	VFIO_DEVICE_FEATURE_MASK	(0xffff) /* 16-bit feature index */
+#define	VFIO_DEVICE_FEATURE_GET		(1 << 16) /* Get feature into data[] */
+#define	VFIO_DEVICE_FEATURE_SET		(1 << 17) /* Set feature from data[] */
+#define	VFIO_DEVICE_FEATURE_PROBE	(1 << 18) /* Probe feature support */
+	__u8	data[];
+};
+#endif
+
+#ifdef	VFIO_DEVICE_FEATURE_BUS_MASTER
+#define	RTE_VFIO_DEVICE_FEATURE_BUS_MASTER	VFIO_DEVICE_FEATURE_BUS_MASTER
+#else
+#define	RTE_VFIO_DEVICE_FEATURE_BUS_MASTER	10
+struct vfio_device_feature_bus_master {
+	__u32 op;
+#define	VFIO_DEVICE_FEATURE_CLEAR_MASTER	0	/* Clear Bus Master */
+#define	VFIO_DEVICE_FEATURE_SET_MASTER		1	/* Set Bus Master */
+};
+#endif
+
 #else /* not VFIO_PRESENT */
 
 /* we don't need an actual definition, only pointer is used */
-- 
2.25.1