dmaengine: idxd: expose fault counters to sysfs

Expose cr_faults and cr_fault_failures counters to the user space. This
allows a user app to keep track of how many fault the application is
causing with the completion record (CR) and also the number of failures
of the CR writeback. Having a high number of cr_fault_failures is bad as
the app is submitting descriptors with the CR addresses that are bad. User
monitoring daemon may want to consider killing the application as it may be
malicious and attempting to flood the device event log.

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/20230407203143.2189681-15-fenghua.yu@intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files changed, 46 insertions, 0 deletions

diff --git a/drivers/dma/idxd/cdev.c b/drivers/dma/idxd/cdev.c
index e07411053e21..2fb905f2545b 100644
--- a/drivers/dma/idxd/cdev.c
+++ b/drivers/dma/idxd/cdev.c
@@ -61,6 +61,51 @@ static inline struct idxd_user_context *dev_to_uctx(struct device *dev)
 	return container_of(idxd_dev, struct idxd_user_context, idxd_dev);
 }
 
+static ssize_t cr_faults_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct idxd_user_context *ctx = dev_to_uctx(dev);
+
+	return sysfs_emit(buf, "%llu\n", ctx->counters[COUNTER_FAULTS]);
+}
+static DEVICE_ATTR_RO(cr_faults);
+
+static ssize_t cr_fault_failures_show(struct device *dev,
+				      struct device_attribute *attr, char *buf)
+{
+	struct idxd_user_context *ctx = dev_to_uctx(dev);
+
+	return sysfs_emit(buf, "%llu\n", ctx->counters[COUNTER_FAULT_FAILS]);
+}
+static DEVICE_ATTR_RO(cr_fault_failures);
+
+static struct attribute *cdev_file_attributes[] = {
+	&dev_attr_cr_faults.attr,
+	&dev_attr_cr_fault_failures.attr,
+	NULL
+};
+
+static umode_t cdev_file_attr_visible(struct kobject *kobj, struct attribute *a, int n)
+{
+	struct device *dev = container_of(kobj, typeof(*dev), kobj);
+	struct idxd_user_context *ctx = dev_to_uctx(dev);
+	struct idxd_wq *wq = ctx->wq;
+
+	if (!wq_pasid_enabled(wq))
+		return 0;
+
+	return a->mode;
+}
+
+static const struct attribute_group cdev_file_attribute_group = {
+	.attrs = cdev_file_attributes,
+	.is_visible = cdev_file_attr_visible,
+};
+
+static const struct attribute_group *cdev_file_attribute_groups[] = {
+	&cdev_file_attribute_group,
+	NULL
+};
+
 static void idxd_file_dev_release(struct device *dev)
 {
 	struct idxd_user_context *ctx = dev_to_uctx(dev);
@@ -100,6 +145,7 @@ static void idxd_file_dev_release(struct device *dev)
 static struct device_type idxd_cdev_file_type = {
 	.name = "idxd_file",
 	.release = idxd_file_dev_release,
+	.groups = cdev_file_attribute_groups,
 };
 
 static void idxd_cdev_dev_release(struct device *dev)