dmaengine: idxd: add a device to represent the file opened

Embed a struct device for the user file context in order to export sysfs
attributes related with the opened file. Tie the lifetime of the file
context to the device. The sysfs entry will be added under the char device.

Tested-by: Tony Zhu <tony.zhu@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Co-developed-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Link: https://lore.kernel.org/r/20230407203143.2189681-14-fenghua.yu@intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Author: davejiang

drivers/dma/idxd/cdev.c

@@ -23,6 +23,13 @@ struct idxd_cdev_context {
 	struct ida minor_ida;
 };
 
+/*
+ * Since user file names are global in DSA devices, define their ida's as
+ * global to avoid conflict file names.
+ */
+static DEFINE_IDA(file_ida);
+static DEFINE_MUTEX(ida_lock);
+
 /*
  * ictx is an array based off of accelerator types. enum idxd_type
  * is used as index
@@ -39,7 +46,60 @@ struct idxd_user_context {
 	struct mm_struct *mm;
 	unsigned int flags;
 	struct iommu_sva *sva;
+	struct idxd_dev idxd_dev;
 	u64 counters[COUNTER_MAX];
+	int id;
+};
+
+static void idxd_cdev_evl_drain_pasid(struct idxd_wq *wq, u32 pasid);
+static void idxd_xa_pasid_remove(struct idxd_user_context *ctx);
+
+static inline struct idxd_user_context *dev_to_uctx(struct device *dev)
+{
+	struct idxd_dev *idxd_dev = confdev_to_idxd_dev(dev);
+
+	return container_of(idxd_dev, struct idxd_user_context, idxd_dev);
+}
+
+static void idxd_file_dev_release(struct device *dev)
+{
+	struct idxd_user_context *ctx = dev_to_uctx(dev);
+	struct idxd_wq *wq = ctx->wq;
+	struct idxd_device *idxd = wq->idxd;
+	int rc;
+
+	mutex_lock(&ida_lock);
+	ida_free(&file_ida, ctx->id);
+	mutex_unlock(&ida_lock);
+
+	/* Wait for in-flight operations to complete. */
+	if (wq_shared(wq)) {
+		idxd_device_drain_pasid(idxd, ctx->pasid);
+	} else {
+		if (device_user_pasid_enabled(idxd)) {
+			/* The wq disable in the disable pasid function will drain the wq */
+			rc = idxd_wq_disable_pasid(wq);
+			if (rc < 0)
+				dev_err(dev, "wq disable pasid failed.\n");
+		} else {
+			idxd_wq_drain(wq);
+		}
+	}
+
+	if (ctx->sva) {
+		idxd_cdev_evl_drain_pasid(wq, ctx->pasid);
+		iommu_sva_unbind_device(ctx->sva);
+		idxd_xa_pasid_remove(ctx);
+	}
+	kfree(ctx);
+	mutex_lock(&wq->wq_lock);
+	idxd_wq_put(wq);
+	mutex_unlock(&wq->wq_lock);
+}
+
+static struct device_type idxd_cdev_file_type = {
+	.name = "idxd_file",
+	.release = idxd_file_dev_release,
 };
 
 static void idxd_cdev_dev_release(struct device *dev)
@@ -107,10 +167,11 @@ static int idxd_cdev_open(struct inode *inode, struct file *filp)
 	struct idxd_user_context *ctx;
 	struct idxd_device *idxd;
 	struct idxd_wq *wq;
-	struct device *dev;
+	struct device *dev, *fdev;
 	int rc = 0;
 	struct iommu_sva *sva;
 	unsigned int pasid;
+	struct idxd_cdev *idxd_cdev;
 
 	wq = inode_wq(inode);
 	idxd = wq->idxd;
@@ -166,10 +227,41 @@ static int idxd_cdev_open(struct inode *inode, struct file *filp)
 		}
 	}
 
+	idxd_cdev = wq->idxd_cdev;
+	mutex_lock(&ida_lock);
+	ctx->id = ida_alloc(&file_ida, GFP_KERNEL);
+	mutex_unlock(&ida_lock);
+	if (ctx->id < 0) {
+		dev_warn(dev, "ida alloc failure\n");
+		goto failed_ida;
+	}
+	ctx->idxd_dev.type  = IDXD_DEV_CDEV_FILE;
+	fdev = user_ctx_dev(ctx);
+	device_initialize(fdev);
+	fdev->parent = cdev_dev(idxd_cdev);
+	fdev->bus = &dsa_bus_type;
+	fdev->type = &idxd_cdev_file_type;
+
+	rc = dev_set_name(fdev, "file%d", ctx->id);
+	if (rc < 0) {
+		dev_warn(dev, "set name failure\n");
+		goto failed_dev_name;
+	}
+
+	rc = device_add(fdev);
+	if (rc < 0) {
+		dev_warn(dev, "file device add failure\n");
+		goto failed_dev_add;
+	}
+
 	idxd_wq_get(wq);
 	mutex_unlock(&wq->wq_lock);
 	return 0;
 
+failed_dev_add:
+failed_dev_name:
+	put_device(fdev);
+failed_ida:
 failed_set_pasid:
 	if (device_user_pasid_enabled(idxd))
 		idxd_xa_pasid_remove(ctx);
@@ -217,34 +309,12 @@ static int idxd_cdev_release(struct inode *node, struct file *filep)
 	struct idxd_wq *wq = ctx->wq;
 	struct idxd_device *idxd = wq->idxd;
 	struct device *dev = &idxd->pdev->dev;
-	int rc;
 
 	dev_dbg(dev, "%s called\n", __func__);
 	filep->private_data = NULL;
 
-	/* Wait for in-flight operations to complete. */
-	if (wq_shared(wq)) {
-		idxd_device_drain_pasid(idxd, ctx->pasid);
-	} else {
-		if (device_user_pasid_enabled(idxd)) {
-			/* The wq disable in the disable pasid function will drain the wq */
-			rc = idxd_wq_disable_pasid(wq);
-			if (rc < 0)
-				dev_err(dev, "wq disable pasid failed.\n");
-		} else {
-			idxd_wq_drain(wq);
-		}
-	}
+	device_unregister(user_ctx_dev(ctx));
 
-	if (ctx->sva) {
-		idxd_cdev_evl_drain_pasid(wq, ctx->pasid);
-		iommu_sva_unbind_device(ctx->sva);
-		idxd_xa_pasid_remove(ctx);
-	}
-	kfree(ctx);
-	mutex_lock(&wq->wq_lock);
-	idxd_wq_put(wq);
-	mutex_unlock(&wq->wq_lock);
 	return 0;
 }
 
@@ -375,6 +445,7 @@ void idxd_wq_del_cdev(struct idxd_wq *wq)
 	struct idxd_cdev *idxd_cdev;
 
 	idxd_cdev = wq->idxd_cdev;
+	ida_destroy(&file_ida);
 	wq->idxd_cdev = NULL;
 	cdev_device_del(&idxd_cdev->cdev, cdev_dev(idxd_cdev));
 	put_device(cdev_dev(idxd_cdev));

drivers/dma/idxd/idxd.h

@@ -32,6 +32,7 @@ enum idxd_dev_type {
 	IDXD_DEV_GROUP,
 	IDXD_DEV_ENGINE,
 	IDXD_DEV_CDEV,
+	IDXD_DEV_CDEV_FILE,
 	IDXD_DEV_MAX_TYPE,
 };
 
@@ -405,6 +406,7 @@ enum idxd_completion_status {
 #define engine_confdev(engine) &engine->idxd_dev.conf_dev
 #define group_confdev(group) &group->idxd_dev.conf_dev
 #define cdev_dev(cdev) &cdev->idxd_dev.conf_dev
+#define user_ctx_dev(ctx) (&(ctx)->idxd_dev.conf_dev)
 
 #define confdev_to_idxd_dev(dev) container_of(dev, struct idxd_dev, conf_dev)
 #define idxd_dev_to_idxd(idxd_dev) container_of(idxd_dev, struct idxd_device, idxd_dev)