[PATCH v1 03/14] cxl/region: Add dynamic DAX region support

[Anisa Su <anisa.su887@gmail.com>]

From: Ira Weiny <iweiny@kernel.org>

CXL DAX regions must allow memory to be added or removed dynamically
to support DCD. In addition to the quantity of memory available, the
location of the memory within a DC partition is dynamic, based on the
extents offered by a device.  CXL DAX regions must accommodate the
dynamic movement of this memory in the management of DAX regions and
devices.

Introduce the concept of a dynamic DAX region. A dynamic region
carries the shareable and read-only properties of the partitions it
decodes, fixed when the region is created: every endpoint decoder
attached to it must point at a partition with exactly those
properties, and the region's 'mode' reports the matching selector.

A dynamic region has no capacity when it is created, so the DAX device
that cxl_dax_region_probe() creates for every region gets size 0
instead of the region size: a seed that claims no capacity the device
has not offered yet.  Its dax_region is created with IORESOURCE_DAX_DCD
rather than IORESOURCE_DAX_KMEM, so the DAX devices on it bind to
device_dax and not to kmem.

Indicate 0 byte available capacity until such time that capacity is
added.

While DCD is disabled, auto region creation and the region 'target'
write refuse endpoint decoders on a DC partition with -ENXIO, as the
decoder 'mode' write already does. The sysfs entries for manual region
creation follow in a separate patch.

Additionally, dynamic regions complicate the range mapping of dax
devices. There is no known use case for range mapping on dynamic
regions. Avoid the complication by preventing range mapping of dax
devices on dynamic regions.

Interleaving is deferred for now.

Based on an original patch by Navneet Singh.

Signed-off-by: Ira Weiny <iweiny@kernel.org>
Co-developed-by: Anisa Su <anisa.su@samsung.com>
Signed-off-by: Anisa Su <anisa.su@samsung.com>
Tested-by: Wonjae Lee <wj28.lee@samsung.com>
Tested-by: Junhee Park <jh9934.park@samsung.com>
Tested-by: Heesoo Kim <habil.kim@samsung.com>
---
 Documentation/ABI/testing/sysfs-bus-cxl |  5 ++-
 drivers/cxl/core/region.c               | 60 ++++++++++++++++++++++---
 drivers/cxl/core/region_dax.c           |  6 +++
 drivers/cxl/cxl.h                       |  4 ++
 drivers/dax/bus.c                       | 10 +++++
 drivers/dax/bus.h                       |  1 +
 drivers/dax/cxl.c                       | 17 ++++++-
 7 files changed, 93 insertions(+), 10 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl
index bcbc44fea6db..69e4f1fa21b7 100644
--- a/Documentation/ABI/testing/sysfs-bus-cxl
+++ b/Documentation/ABI/testing/sysfs-bus-cxl
@@ -543,7 +543,10 @@ Description:
 		(RO) The mode of a region is established at region creation time
 		and dictates the mode of the endpoint decoder that comprise the
 		region. For more details on the possible modes see
-		/sys/bus/cxl/devices/decoderX.Y/mode
+		/sys/bus/cxl/devices/decoderX.Y/mode. A dynamic capacity
+		region reports the selector it was created with: 'dynamic_ram',
+		'dynamic_ram_shared', 'dynamic_ram_ro' or
+		'dynamic_ram_shared_ro'.
 
 
 What:		/sys/bus/cxl/devices/regionZ/resource
diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index f4a9839c73d2..fc9139ce358f 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -495,6 +495,11 @@ static int set_interleave_ways(struct cxl_region *cxlr, int val)
 	int save, rc;
 	u8 iw;
 
+	if (cxlr->mode == CXL_PARTMODE_DYNAMIC_RAM && val != 1) {
+		dev_dbg(&cxlr->dev, "Interleaving and DCD not supported\n");
+		return -EINVAL;
+	}
+
 	rc = ways_to_eiw(val, &iw);
 	if (rc)
 		return rc;
@@ -644,6 +649,8 @@ static ssize_t mode_show(struct device *dev, struct device_attribute *attr,
 		desc = "ram";
 	else if (cxlr->mode == CXL_PARTMODE_PMEM)
 		desc = "pmem";
+	else if (cxlr->mode == CXL_PARTMODE_DYNAMIC_RAM)
+		desc = cxl_dc_mode_name(cxlr->shareable, cxlr->read_only);
 	else
 		desc = "";
 
@@ -2080,6 +2087,20 @@ static int cxl_region_attach(struct cxl_region *cxlr,
 		return -EINVAL;
 	}
 
+	/* A DC region's flavor is fixed; every member partition must match */
+	if (cxlr->mode == CXL_PARTMODE_DYNAMIC_RAM) {
+		struct cxl_dpa_partition *part = &cxlds->part[cxled->part];
+
+		if (part->shareable != cxlr->shareable ||
+		    part->read_only != cxlr->read_only) {
+			dev_dbg(&cxlr->dev, "%s: partition is %s, region is %s\n",
+				dev_name(&cxled->cxld.dev),
+				cxl_dc_mode_name(part->shareable, part->read_only),
+				cxl_dc_mode_name(cxlr->shareable, cxlr->read_only));
+			return -EINVAL;
+		}
+	}
+
 	/* all full of members, or interleave config not established? */
 	if (p->state > CXL_CONFIG_INTERLEAVE_ACTIVE) {
 		dev_dbg(&cxlr->dev, "region already active\n");
@@ -2411,6 +2432,7 @@ static size_t store_targetN(struct cxl_region *cxlr, const char *buf, int pos,
 	if (sysfs_streq(buf, "\n"))
 		rc = detach_target(cxlr, pos);
 	else {
+		struct cxl_endpoint_decoder *cxled;
 		struct device *dev;
 
 		dev = bus_find_device_by_name(&cxl_bus_type, NULL, buf);
@@ -2422,8 +2444,14 @@ static size_t store_targetN(struct cxl_region *cxlr, const char *buf, int pos,
 			goto out;
 		}
 
-		rc = attach_target(cxlr, to_cxl_endpoint_decoder(dev), pos,
-				   TASK_INTERRUPTIBLE);
+		cxled = to_cxl_endpoint_decoder(dev);
+		if (cxlr->mode == CXL_PARTMODE_DYNAMIC_RAM &&
+		    !cxled_dcd_enabled(cxled)) {
+			dev_dbg(dev, "DCD not enabled\n");
+			rc = -ENXIO;
+			goto out;
+		}
+		rc = attach_target(cxlr, cxled, pos, TASK_INTERRUPTIBLE);
 out:
 		put_device(dev);
 	}
@@ -2737,6 +2765,8 @@ void kill_regions(struct cxl_root_decoder *cxlrd)
  * @cxlrd: root decoder
  * @id: memregion id to create, or memregion_free() on failure
  * @mode: mode for the endpoint decoders of this region
+ * @shareable: dynamic region: its partitions must be shareable
+ * @read_only: dynamic region: its partitions must be read-only
  * @type: select whether this is an expander or accelerator (type-2 or type-3)
  *
  * This is the second step of region initialization. Regions exist within an
@@ -2748,7 +2778,8 @@ void kill_regions(struct cxl_root_decoder *cxlrd)
 static struct cxl_region *devm_cxl_add_region(struct cxl_root_decoder *cxlrd,
 					      int id,
 					      enum cxl_partition_mode mode,
-					      enum cxl_decoder_type type)
+					      enum cxl_decoder_type type,
+					      bool shareable, bool read_only)
 {
 	struct cxl_port *port = to_cxl_port(cxlrd->cxlsd.cxld.dev.parent);
 	struct cxl_region *cxlr;
@@ -2760,6 +2791,8 @@ static struct cxl_region *devm_cxl_add_region(struct cxl_root_decoder *cxlrd,
 		return cxlr;
 	cxlr->mode = mode;
 	cxlr->type = type;
+	cxlr->shareable = shareable;
+	cxlr->read_only = read_only;
 
 	dev = &cxlr->dev;
 	rc = dev_set_name(dev, "region%d", id);
@@ -2803,7 +2836,8 @@ static ssize_t create_ram_region_show(struct device *dev,
 
 static struct cxl_region *__create_region(struct cxl_root_decoder *cxlrd,
 					  enum cxl_partition_mode mode, int id,
-					  enum cxl_decoder_type target_type)
+					  enum cxl_decoder_type target_type,
+					  bool shareable, bool read_only)
 {
 	int rc;
 
@@ -2813,6 +2847,7 @@ static struct cxl_region *__create_region(struct cxl_root_decoder *cxlrd,
 	switch (mode) {
 	case CXL_PARTMODE_RAM:
 	case CXL_PARTMODE_PMEM:
+	case CXL_PARTMODE_DYNAMIC_RAM:
 		break;
 	default:
 		dev_err(&cxlrd->cxlsd.cxld.dev, "unsupported mode %d\n", mode);
@@ -2828,7 +2863,8 @@ static struct cxl_region *__create_region(struct cxl_root_decoder *cxlrd,
 		return ERR_PTR(-EBUSY);
 	}
 
-	return devm_cxl_add_region(cxlrd, id, mode, target_type);
+	return devm_cxl_add_region(cxlrd, id, mode, target_type, shareable,
+				   read_only);
 }
 
 static ssize_t create_region_store(struct device *dev, const char *buf,
@@ -2846,7 +2882,8 @@ static ssize_t create_region_store(struct device *dev, const char *buf,
 	if ((rc = ACQUIRE_ERR(mutex_intr, &regions_lock)))
 		return rc;
 
-	cxlr = __create_region(cxlrd, mode, id, CXL_DECODER_HOSTONLYMEM);
+	cxlr = __create_region(cxlrd, mode, id, CXL_DECODER_HOSTONLYMEM,
+			       false, false);
 	if (IS_ERR(cxlr))
 		return PTR_ERR(cxlr);
 
@@ -3808,10 +3845,18 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
 	if (part < 0)
 		return ERR_PTR(-EBUSY);
 
+	if (cxlds->part[part].mode == CXL_PARTMODE_DYNAMIC_RAM &&
+	    !cxled_dcd_enabled(cxled)) {
+		dev_dbg(&cxled->cxld.dev, "DCD not enabled\n");
+		return ERR_PTR(-ENXIO);
+	}
+
 	do {
 		cxlr = __create_region(cxlrd, cxlds->part[part].mode,
 				       atomic_read(&cxlrd->region_id),
-				       cxled->cxld.target_type);
+				       cxled->cxld.target_type,
+				       cxlds->part[part].shareable,
+				       cxlds->part[part].read_only);
 	} while (IS_ERR(cxlr) && PTR_ERR(cxlr) == -EBUSY);
 
 	if (IS_ERR(cxlr)) {
@@ -4262,6 +4307,7 @@ static int cxl_region_probe(struct device *dev)
 
 		return devm_cxl_add_pmem_region(cxlr);
 	case CXL_PARTMODE_RAM:
+	case CXL_PARTMODE_DYNAMIC_RAM:
 		rc = devm_cxl_region_edac_register(cxlr);
 		if (rc)
 			dev_dbg(&cxlr->dev, "CXL EDAC registration for region_id=%d failed\n",
diff --git a/drivers/cxl/core/region_dax.c b/drivers/cxl/core/region_dax.c
index de04f78f6ad8..47c9c52a3902 100644
--- a/drivers/cxl/core/region_dax.c
+++ b/drivers/cxl/core/region_dax.c
@@ -84,6 +84,12 @@ int devm_cxl_add_dax_region(struct cxl_region *cxlr)
 	struct device *dev;
 	int rc;
 
+	if (cxlr->mode == CXL_PARTMODE_DYNAMIC_RAM &&
+	    cxlr->params.interleave_ways != 1) {
+		dev_dbg(&cxlr->dev, "Interleaving DC not supported\n");
+		return -EINVAL;
+	}
+
 	struct cxl_dax_region *cxlr_dax __free(put_cxl_dax_region) =
 		cxl_dax_region_alloc(cxlr);
 	if (IS_ERR(cxlr_dax))
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index baa6df2d362a..d098f7f50bef 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -490,6 +490,8 @@ struct cxl_region_params {
  * @cxl_nvb: nvdimm bridge for coordinating @cxlr_pmem setup / shutdown
  * @cxlr_pmem: (for pmem regions) cached copy of the nvdimm bridge
  * @flags: Region state flags
+ * @shareable: (for DC regions) backing partitions must be shareable
+ * @read_only: (for DC regions) backing partitions must be read-only
  * @params: active + config params for the region
  * @coord: QoS access coordinates for the region
  * @node_notifier: notifier for setting the access coordinates to node
@@ -506,6 +508,8 @@ struct cxl_region {
 	struct cxl_nvdimm_bridge *cxl_nvb;
 	struct cxl_pmem_region *cxlr_pmem;
 	unsigned long flags;
+	bool shareable;
+	bool read_only;
 	struct cxl_region_params params;
 	struct access_coordinate coord[ACCESS_COORDINATE_MAX];
 	struct notifier_block node_notifier;
diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index e40c25401cf0..d8cc1c012f46 100644
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -177,6 +177,11 @@ static bool is_static(struct dax_region *dax_region)
 	return (dax_region->res.flags & IORESOURCE_DAX_STATIC) != 0;
 }
 
+static bool is_dcd(struct dax_region *dax_region)
+{
+	return (dax_region->res.flags & IORESOURCE_DAX_DCD) != 0;
+}
+
 bool static_dev_dax(struct dev_dax *dev_dax)
 {
 	return is_static(dev_dax->region);
@@ -300,6 +305,9 @@ static unsigned long long dax_region_avail_size(struct dax_region *dax_region)
 
 	lockdep_assert_held(&dax_region_rwsem);
 
+	if (is_dcd(dax_region))
+		return 0;
+
 	for_each_dax_region_resource(dax_region, res)
 		size -= resource_size(res);
 	return size;
@@ -1389,6 +1397,8 @@ static umode_t dev_dax_visible(struct kobject *kobj, struct attribute *a, int n)
 		return 0;
 	if (a == &dev_attr_mapping.attr && is_static(dax_region))
 		return 0;
+	if (a == &dev_attr_mapping.attr && is_dcd(dax_region))
+		return 0;
 	if ((a == &dev_attr_align.attr ||
 	     a == &dev_attr_size.attr) && is_static(dax_region))
 		return 0444;
diff --git a/drivers/dax/bus.h b/drivers/dax/bus.h
index bfc31923f3ff..c877daa8df51 100644
--- a/drivers/dax/bus.h
+++ b/drivers/dax/bus.h
@@ -15,6 +15,7 @@ struct dax_region;
 /* dax bus specific ioresource flags */
 #define IORESOURCE_DAX_STATIC BIT(0)
 #define IORESOURCE_DAX_KMEM BIT(1)
+#define IORESOURCE_DAX_DCD BIT(2)
 
 #define DAX_KMEM_UNPLUGGED	(-1) /* Do not create memory blocks */
 
diff --git a/drivers/dax/cxl.c b/drivers/dax/cxl.c
index 3ab39b77843d..43eb18c8a035 100644
--- a/drivers/dax/cxl.c
+++ b/drivers/dax/cxl.c
@@ -13,19 +13,32 @@ static int cxl_dax_region_probe(struct device *dev)
 	struct cxl_region *cxlr = cxlr_dax->cxlr;
 	struct dax_region *dax_region;
 	struct dev_dax_data data;
+	resource_size_t dev_size;
+	unsigned long flags;
 
 	if (nid == NUMA_NO_NODE)
 		nid = memory_add_physaddr_to_nid(cxlr_dax->hpa_range.start);
 
+	if (cxlr->mode == CXL_PARTMODE_DYNAMIC_RAM)
+		flags = IORESOURCE_DAX_DCD;
+	else
+		flags = IORESOURCE_DAX_KMEM;
+
 	dax_region = alloc_dax_region(dev, cxlr->id, &cxlr_dax->hpa_range, nid,
-				      PMD_SIZE, IORESOURCE_DAX_KMEM);
+				      PMD_SIZE, flags);
 	if (!dax_region)
 		return -ENOMEM;
 
+	if (cxlr->mode == CXL_PARTMODE_DYNAMIC_RAM)
+		/* Add empty seed dax device */
+		dev_size = 0;
+	else
+		dev_size = range_len(&cxlr_dax->hpa_range);
+
 	data = (struct dev_dax_data) {
 		.dax_region = dax_region,
 		.id = -1,
-		.size = range_len(&cxlr_dax->hpa_range),
+		.size = dev_size,
 		.memmap_on_memory = true,
 	};
 
-- 
2.43.0