drm/amdgpu: add badpages sysfs interafce

add badpages node.
it will output badpages list in format
gpu pfn : gpu page size : flags

example
0x00000000 : 0x00001000 : R
0x00000001 : 0x00001000 : R
0x00000002 : 0x00001000 : R
0x00000003 : 0x00001000 : R
0x00000004 : 0x00001000 : R
0x00000005 : 0x00001000 : R
0x00000006 : 0x00001000 : R
0x00000007 : 0x00001000 : P
0x00000008 : 0x00001000 : P
0x00000009 : 0x00001000 : P

flags can be one of below characters
R: reserved.
P: pending for reserve.
F: failed to reserve for some reasons.
Signed-off-by: xinhui pan <xinhui.pan@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c

@@ -90,6 +90,12 @@ struct ras_manager {
 	struct ras_err_data err_data;
 };
 
+struct ras_badpage {
+	unsigned int bp;
+	unsigned int size;
+	unsigned int flags;
+};
+
 const char *ras_error_string[] = {
 	"none",
 	"parity",
@@ -710,6 +716,77 @@ int amdgpu_ras_query_error_count(struct amdgpu_device *adev,
 
 /* sysfs begin */
 
+static int amdgpu_ras_badpages_read(struct amdgpu_device *adev,
+		struct ras_badpage **bps, unsigned int *count);
+
+static char *amdgpu_ras_badpage_flags_str(unsigned int flags)
+{
+	switch (flags) {
+	case 0:
+		return "R";
+	case 1:
+		return "P";
+	case 2:
+	default:
+		return "F";
+	};
+}
+
+/*
+ * DOC: ras sysfs gpu_vram_bad_pages interface
+ *
+ * It allows user to read the bad pages of vram on the gpu through
+ * /sys/class/drm/card[0/1/2...]/device/ras/gpu_vram_bad_pages
+ *
+ * It outputs multiple lines, and each line stands for one gpu page.
+ *
+ * The format of one line is below,
+ * gpu pfn : gpu page size : flags
+ *
+ * gpu pfn and gpu page size are printed in hex format.
+ * flags can be one of below character,
+ * R: reserved, this gpu page is reserved and not able to use.
+ * P: pending for reserve, this gpu page is marked as bad, will be reserved
+ *    in next window of page_reserve.
+ * F: unable to reserve. this gpu page can't be reserved due to some reasons.
+ *
+ * examples:
+ * 0x00000001 : 0x00001000 : R
+ * 0x00000002 : 0x00001000 : P
+ */
+
+static ssize_t amdgpu_ras_sysfs_badpages_read(struct file *f,
+		struct kobject *kobj, struct bin_attribute *attr,
+		char *buf, loff_t ppos, size_t count)
+{
+	struct amdgpu_ras *con =
+		container_of(attr, struct amdgpu_ras, badpages_attr);
+	struct amdgpu_device *adev = con->adev;
+	const unsigned int element_size =
+		sizeof("0xabcdabcd : 0x12345678 : R\n") - 1;
+	unsigned int start = (ppos + element_size - 1) / element_size;
+	unsigned int end = (ppos + count - 1) / element_size;
+	ssize_t s = 0;
+	struct ras_badpage *bps = NULL;
+	unsigned int bps_count = 0;
+
+	memset(buf, 0, count);
+
+	if (amdgpu_ras_badpages_read(adev, &bps, &bps_count))
+		return 0;
+
+	for (; start < end && start < bps_count; start++)
+		s += scnprintf(&buf[s], element_size + 1,
+				"0x%08x : 0x%08x : %1s\n",
+				bps[start].bp,
+				bps[start].size,
+				amdgpu_ras_badpage_flags_str(bps[start].flags));
+
+	kfree(bps);
+
+	return s;
+}
+
 static ssize_t amdgpu_ras_sysfs_features_read(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
@@ -750,9 +827,14 @@ static int amdgpu_ras_sysfs_create_feature_node(struct amdgpu_device *adev)
 		&con->features_attr.attr,
 		NULL
 	};
+	struct bin_attribute *bin_attrs[] = {
+		&con->badpages_attr,
+		NULL
+	};
 	struct attribute_group group = {
 		.name = "ras",
 		.attrs = attrs,
+		.bin_attrs = bin_attrs,
 	};
 
 	con->features_attr = (struct device_attribute) {
@@ -762,7 +844,19 @@ static int amdgpu_ras_sysfs_create_feature_node(struct amdgpu_device *adev)
 		},
 			.show = amdgpu_ras_sysfs_features_read,
 	};
+
+	con->badpages_attr = (struct bin_attribute) {
+		.attr = {
+			.name = "gpu_vram_bad_pages",
+			.mode = S_IRUGO,
+		},
+		.size = 0,
+		.private = NULL,
+		.read = amdgpu_ras_sysfs_badpages_read,
+	};
+
 	sysfs_attr_init(attrs[0]);
+	sysfs_bin_attr_init(bin_attrs[0]);
 
 	return sysfs_create_group(&adev->dev->kobj, &group);
 }
@@ -774,9 +868,14 @@ static int amdgpu_ras_sysfs_remove_feature_node(struct amdgpu_device *adev)
 		&con->features_attr.attr,
 		NULL
 	};
+	struct bin_attribute *bin_attrs[] = {
+		&con->badpages_attr,
+		NULL
+	};
 	struct attribute_group group = {
 		.name = "ras",
 		.attrs = attrs,
+		.bin_attrs = bin_attrs,
 	};
 
 	sysfs_remove_group(&adev->dev->kobj, &group);
@@ -1108,6 +1207,53 @@ static int amdgpu_ras_interrupt_remove_all(struct amdgpu_device *adev)
 /* ih end */
 
 /* recovery begin */
+
+/* return 0 on success.
+ * caller need free bps.
+ */
+static int amdgpu_ras_badpages_read(struct amdgpu_device *adev,
+		struct ras_badpage **bps, unsigned int *count)
+{
+	struct amdgpu_ras *con = amdgpu_ras_get_context(adev);
+	struct ras_err_handler_data *data;
+	int i = 0;
+	int ret = 0;
+
+	if (!con || !con->eh_data || !bps || !count)
+		return -EINVAL;
+
+	mutex_lock(&con->recovery_lock);
+	data = con->eh_data;
+	if (!data || data->count == 0) {
+		*bps = NULL;
+		goto out;
+	}
+
+	*bps = kmalloc(sizeof(struct ras_badpage) * data->count, GFP_KERNEL);
+	if (!*bps) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	for (; i < data->count; i++) {
+		(*bps)[i] = (struct ras_badpage){
+			.bp = data->bps[i].bp,
+			.size = AMDGPU_GPU_PAGE_SIZE,
+			.flags = 0,
+		};
+
+		if (data->last_reserved <= i)
+			(*bps)[i].flags = 1;
+		else if (data->bps[i].bo == NULL)
+			(*bps)[i].flags = 2;
+	}
+
+	*count = data->count;
+out:
+	mutex_unlock(&con->recovery_lock);
+	return ret;
+}
+
 static void amdgpu_ras_do_recovery(struct work_struct *work)
 {
 	struct amdgpu_ras *ras =

drivers/gpu/drm/amd/amdgpu/amdgpu_ras.h

@@ -93,6 +93,7 @@ struct amdgpu_ras {
 	struct dentry *ent;
 	/* sysfs */
 	struct device_attribute features_attr;
+	struct bin_attribute badpages_attr;
 	/* block array */
 	struct ras_manager *objs;