@@ -342,3 +342,22 @@ Description:
size attribute, the resulting physical address space determined
by the driver is reflected here. It is therefore not useful to
read this before writing a value to the size attribute.
+
+
+What: /sys/bus/cxl/devices/regionZ/target[0..N]
+Date: May, 2022
+KernelVersion: v5.20
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RW) Write an endpoint decoder object name to 'targetX' where X
+ is the intended position of the endpoint device in the region
+ interleave and N is the 'interleave_ways' setting for the
+ region. ENXIO is returned if the write results in an impossible
+ to map decode scenario, like the endpoint is unreachable at that
+ position relative to the root decoder interleave. EBUSY is
+ returned if the position in the region is already occupied, or
+ if the region is not in a state to accept interleave
+ configuration changes. EINVAL is returned if the object name is
+ not an endpoint decoder. Once all positions have been
+ successfully written a final validation for decode conflicts is
+ performed before activating the region.
@@ -12,9 +12,14 @@ extern struct attribute_group cxl_base_attribute_group;
#ifdef CONFIG_CXL_REGION
extern struct device_attribute dev_attr_create_pmem_region;
extern struct device_attribute dev_attr_delete_region;
+extern struct device_attribute dev_attr_region;
+void cxl_decoder_kill_region(struct cxl_endpoint_decoder *cxled);
#define CXL_REGION_ATTR(x) (&dev_attr_##x.attr)
#define SET_CXL_REGION_ATTR(x) (&dev_attr_##x.attr),
#else
+static inline void cxl_decoder_kill_region(struct cxl_endpoint_decoder *cxled)
+{
+}
#define CXL_REGION_ATTR(x) NULL
#define SET_CXL_REGION_ATTR(x)
#endif
@@ -34,6 +39,7 @@ int cxl_dpa_alloc(struct cxl_endpoint_decoder *cxled, unsigned long long size);
int cxl_dpa_free(struct cxl_endpoint_decoder *cxled);
resource_size_t cxl_dpa_size(struct cxl_endpoint_decoder *cxled);
resource_size_t cxl_dpa_resource_start(struct cxl_endpoint_decoder *cxled);
+extern struct rw_semaphore cxl_dpa_rwsem;
int cxl_memdev_init(void);
void cxl_memdev_exit(void);
@@ -17,7 +17,7 @@
* for enumerating these registers and capabilities.
*/
-static DECLARE_RWSEM(cxl_dpa_rwsem);
+DECLARE_RWSEM(cxl_dpa_rwsem);
static int add_hdm_decoder(struct cxl_port *port, struct cxl_decoder *cxld,
int *target_map)
@@ -319,6 +319,11 @@ int cxl_dpa_free(struct cxl_endpoint_decoder *cxled)
rc = 0;
goto out;
}
+ if (cxled->cxld.region) {
+ dev_dbg(dev, "decoder assigned to: %s\n",
+ dev_name(&cxled->cxld.region->dev));
+ goto out;
+ }
if (cxled->cxld.flags & CXL_DECODER_F_ENABLE) {
dev_dbg(dev, "decoder enabled\n");
rc = -EBUSY;
@@ -395,6 +400,12 @@ int cxl_dpa_alloc(struct cxl_endpoint_decoder *cxled, unsigned long long size)
int rc;
down_write(&cxl_dpa_rwsem);
+ if (cxled->cxld.region) {
+ dev_dbg(dev, "decoder attached to %s\n",
+ dev_name(&cxled->cxld.region->dev));
+ goto out;
+ }
+
if (cxled->cxld.flags & CXL_DECODER_F_ENABLE) {
dev_dbg(dev, "decoder enabled\n");
rc = -EBUSY;
@@ -288,6 +288,7 @@ static struct attribute *cxl_decoder_base_attrs[] = {
&dev_attr_locked.attr,
&dev_attr_interleave_granularity.attr,
&dev_attr_interleave_ways.attr,
+ SET_CXL_REGION_ATTR(region)
NULL,
};
@@ -1583,6 +1584,7 @@ struct cxl_endpoint_decoder *cxl_endpoint_decoder_alloc(struct cxl_port *port)
if (!cxled)
return ERR_PTR(-ENOMEM);
+ cxled->pos = -1;
cxld = &cxled->cxld;
rc = cxl_decoder_init(port, cxld);
if (rc) {
@@ -1687,6 +1689,13 @@ EXPORT_SYMBOL_NS_GPL(cxl_decoder_add, CXL);
static void cxld_unregister(void *dev)
{
+ struct cxl_endpoint_decoder *cxled;
+
+ if (is_endpoint_decoder(dev)) {
+ cxled = to_cxl_endpoint_decoder(dev);
+ cxl_decoder_kill_region(cxled);
+ }
+
device_unregister(dev);
}
@@ -24,6 +24,7 @@
* but is only visible for persistent regions.
* 1. Interleave granularity
* 2. Interleave size
+ * 3. Decoder targets
*/
/*
@@ -141,6 +142,8 @@ static ssize_t interleave_ways_show(struct device *dev,
return rc;
}
+static const struct attribute_group *get_cxl_region_target_group(void);
+
static ssize_t interleave_ways_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t len)
@@ -149,7 +152,7 @@ static ssize_t interleave_ways_store(struct device *dev,
struct cxl_decoder *cxld = &cxlrd->cxlsd.cxld;
struct cxl_region *cxlr = to_cxl_region(dev);
struct cxl_region_params *p = &cxlr->params;
- int rc, val;
+ int rc, val, save;
u8 iw;
rc = kstrtoint(buf, 0, &val);
@@ -178,7 +181,11 @@ static ssize_t interleave_ways_store(struct device *dev,
goto out;
}
+ save = p->interleave_ways;
p->interleave_ways = val;
+ rc = sysfs_update_group(&cxlr->dev.kobj, get_cxl_region_target_group());
+ if (rc)
+ p->interleave_ways = save;
out:
up_write(&cxl_region_rwsem);
if (rc)
@@ -398,9 +405,262 @@ static const struct attribute_group cxl_region_group = {
.is_visible = cxl_region_visible,
};
+static size_t show_targetN(struct cxl_region *cxlr, char *buf, int pos)
+{
+ struct cxl_region_params *p = &cxlr->params;
+ struct cxl_endpoint_decoder *cxled;
+ int rc;
+
+ rc = down_read_interruptible(&cxl_region_rwsem);
+ if (rc)
+ return rc;
+
+ if (pos >= p->interleave_ways) {
+ dev_dbg(&cxlr->dev, "position %d out of range %d\n", pos,
+ p->interleave_ways);
+ rc = -ENXIO;
+ goto out;
+ }
+
+ cxled = p->targets[pos];
+ if (!cxled)
+ rc = sysfs_emit(buf, "\n");
+ else
+ rc = sysfs_emit(buf, "%s\n", dev_name(&cxled->cxld.dev));
+out:
+ up_read(&cxl_region_rwsem);
+
+ return rc;
+}
+
+/*
+ * - Check that the given endpoint is attached to a host-bridge identified
+ * in the root interleave.
+ */
+static int cxl_region_attach(struct cxl_region *cxlr,
+ struct cxl_endpoint_decoder *cxled, int pos)
+{
+ struct cxl_region_params *p = &cxlr->params;
+
+ if (cxled->mode == CXL_DECODER_DEAD) {
+ dev_dbg(&cxlr->dev, "%s dead\n", dev_name(&cxled->cxld.dev));
+ return -ENODEV;
+ }
+
+ if (pos >= p->interleave_ways) {
+ dev_dbg(&cxlr->dev, "position %d out of range %d\n", pos,
+ p->interleave_ways);
+ return -ENXIO;
+ }
+
+ if (p->targets[pos] == cxled)
+ return 0;
+
+ if (p->targets[pos]) {
+ struct cxl_endpoint_decoder *cxled_target = p->targets[pos];
+ struct cxl_memdev *cxlmd_target = cxled_to_memdev(cxled_target);
+
+ dev_dbg(&cxlr->dev, "position %d already assigned to %s:%s\n",
+ pos, dev_name(&cxlmd_target->dev),
+ dev_name(&cxled_target->cxld.dev));
+ return -EBUSY;
+ }
+
+ p->targets[pos] = cxled;
+ cxled->pos = pos;
+ p->nr_targets++;
+
+ return 0;
+}
+
+static void cxl_region_detach(struct cxl_endpoint_decoder *cxled)
+{
+ struct cxl_region *cxlr = cxled->cxld.region;
+ struct cxl_region_params *p;
+
+ lockdep_assert_held_write(&cxl_region_rwsem);
+
+ if (!cxlr)
+ return;
+
+ p = &cxlr->params;
+ get_device(&cxlr->dev);
+
+ if (cxled->pos < 0 || cxled->pos >= p->interleave_ways ||
+ p->targets[cxled->pos] != cxled) {
+ struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
+
+ dev_WARN_ONCE(&cxlr->dev, 1, "expected %s:%s at position %d\n",
+ dev_name(&cxlmd->dev), dev_name(&cxled->cxld.dev),
+ cxled->pos);
+ goto out;
+ }
+
+ p->targets[cxled->pos] = NULL;
+ p->nr_targets--;
+
+ /* notify the region driver that one of its targets has deparated */
+ up_write(&cxl_region_rwsem);
+ device_release_driver(&cxlr->dev);
+ down_write(&cxl_region_rwsem);
+out:
+ put_device(&cxlr->dev);
+}
+
+void cxl_decoder_kill_region(struct cxl_endpoint_decoder *cxled)
+{
+ down_write(&cxl_region_rwsem);
+ cxled->mode = CXL_DECODER_DEAD;
+ cxl_region_detach(cxled);
+ up_write(&cxl_region_rwsem);
+}
+
+static int attach_target(struct cxl_region *cxlr, const char *decoder, int pos)
+{
+ struct device *dev;
+ int rc;
+
+ dev = bus_find_device_by_name(&cxl_bus_type, NULL, decoder);
+ if (!dev)
+ return -ENODEV;
+
+ if (!is_endpoint_decoder(dev)) {
+ put_device(dev);
+ return -EINVAL;
+ }
+
+ rc = down_write_killable(&cxl_region_rwsem);
+ if (rc)
+ goto out;
+ down_read(&cxl_dpa_rwsem);
+ rc = cxl_region_attach(cxlr, to_cxl_endpoint_decoder(dev), pos);
+ up_read(&cxl_dpa_rwsem);
+ up_write(&cxl_region_rwsem);
+out:
+ put_device(dev);
+ return rc;
+}
+
+static int detach_target(struct cxl_region *cxlr, int pos)
+{
+ struct cxl_region_params *p = &cxlr->params;
+ int rc;
+
+ rc = down_write_killable(&cxl_region_rwsem);
+ if (rc)
+ return rc;
+
+ if (pos >= p->interleave_ways) {
+ dev_dbg(&cxlr->dev, "position %d out of range %d\n", pos,
+ p->interleave_ways);
+ rc = -ENXIO;
+ goto out;
+ }
+
+ if (!p->targets[pos]) {
+ rc = 0;
+ goto out;
+ }
+
+ cxl_region_detach(p->targets[pos]);
+ rc = 0;
+out:
+ up_write(&cxl_region_rwsem);
+ return rc;
+}
+
+static size_t store_targetN(struct cxl_region *cxlr, const char *buf, int pos,
+ size_t len)
+{
+ int rc;
+
+ if (sysfs_streq(buf, "\n"))
+ rc = detach_target(cxlr, pos);
+ else
+ rc = attach_target(cxlr, buf, pos);
+
+ if (rc < 0)
+ return rc;
+ return len;
+}
+
+#define TARGET_ATTR_RW(n) \
+static ssize_t target##n##_show( \
+ struct device *dev, struct device_attribute *attr, char *buf) \
+{ \
+ return show_targetN(to_cxl_region(dev), buf, (n)); \
+} \
+static ssize_t target##n##_store(struct device *dev, \
+ struct device_attribute *attr, \
+ const char *buf, size_t len) \
+{ \
+ return store_targetN(to_cxl_region(dev), buf, (n), len); \
+} \
+static DEVICE_ATTR_RW(target##n)
+
+TARGET_ATTR_RW(0);
+TARGET_ATTR_RW(1);
+TARGET_ATTR_RW(2);
+TARGET_ATTR_RW(3);
+TARGET_ATTR_RW(4);
+TARGET_ATTR_RW(5);
+TARGET_ATTR_RW(6);
+TARGET_ATTR_RW(7);
+TARGET_ATTR_RW(8);
+TARGET_ATTR_RW(9);
+TARGET_ATTR_RW(10);
+TARGET_ATTR_RW(11);
+TARGET_ATTR_RW(12);
+TARGET_ATTR_RW(13);
+TARGET_ATTR_RW(14);
+TARGET_ATTR_RW(15);
+
+static struct attribute *target_attrs[] = {
+ &dev_attr_target0.attr,
+ &dev_attr_target1.attr,
+ &dev_attr_target2.attr,
+ &dev_attr_target3.attr,
+ &dev_attr_target4.attr,
+ &dev_attr_target5.attr,
+ &dev_attr_target6.attr,
+ &dev_attr_target7.attr,
+ &dev_attr_target8.attr,
+ &dev_attr_target9.attr,
+ &dev_attr_target10.attr,
+ &dev_attr_target11.attr,
+ &dev_attr_target12.attr,
+ &dev_attr_target13.attr,
+ &dev_attr_target14.attr,
+ &dev_attr_target15.attr,
+ NULL,
+};
+
+static umode_t cxl_region_target_visible(struct kobject *kobj,
+ struct attribute *a, int n)
+{
+ struct device *dev = kobj_to_dev(kobj);
+ struct cxl_region *cxlr = to_cxl_region(dev);
+ struct cxl_region_params *p = &cxlr->params;
+
+ if (n < p->interleave_ways)
+ return a->mode;
+ return 0;
+}
+
+static const struct attribute_group cxl_region_target_group = {
+ .attrs = target_attrs,
+ .is_visible = cxl_region_target_visible,
+};
+
+static const struct attribute_group *get_cxl_region_target_group(void)
+{
+ return &cxl_region_target_group;
+}
+
static const struct attribute_group *region_groups[] = {
&cxl_base_attribute_group,
&cxl_region_group,
+ &cxl_region_target_group,
NULL,
};
@@ -560,6 +820,26 @@ static ssize_t create_pmem_region_store(struct device *dev,
}
DEVICE_ATTR_RW(create_pmem_region);
+static ssize_t region_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct cxl_decoder *cxld = to_cxl_decoder(dev);
+ ssize_t rc;
+
+ rc = down_read_interruptible(&cxl_region_rwsem);
+ if (rc)
+ return rc;
+
+ if (cxld->region)
+ rc = sysfs_emit(buf, "%s\n", dev_name(&cxld->region->dev));
+ else
+ rc = sysfs_emit(buf, "\n");
+ up_read(&cxl_region_rwsem);
+
+ return rc;
+}
+DEVICE_ATTR_RO(region);
+
static struct cxl_region *
cxl_find_region_by_name(struct cxl_root_decoder *cxlrd, const char *name)
{
@@ -255,6 +255,7 @@ enum cxl_decoder_type {
* @interleave_ways: number of cxl_dports in this decode
* @interleave_granularity: data stride per dport
* @target_type: accelerator vs expander (type2 vs type3) selector
+ * @region: currently assigned region for this decoder
* @flags: memory type capabilities and locking
*/
struct cxl_decoder {
@@ -264,14 +265,20 @@ struct cxl_decoder {
int interleave_ways;
int interleave_granularity;
enum cxl_decoder_type target_type;
+ struct cxl_region *region;
unsigned long flags;
};
+/*
+ * CXL_DECODER_DEAD prevents endpoints from being reattached to regions
+ * while cxld_unregister() is running
+ */
enum cxl_decoder_mode {
CXL_DECODER_NONE,
CXL_DECODER_RAM,
CXL_DECODER_PMEM,
CXL_DECODER_MIXED,
+ CXL_DECODER_DEAD,
};
/**
@@ -280,12 +287,14 @@ enum cxl_decoder_mode {
* @dpa_res: actively claimed DPA span of this decoder
* @skip: offset into @dpa_res where @cxld.hpa_range maps
* @mode: which memory type / access-mode-partition this decoder targets
+ * @pos: interleave position in @cxld.region
*/
struct cxl_endpoint_decoder {
struct cxl_decoder cxld;
struct resource *dpa_res;
resource_size_t skip;
enum cxl_decoder_mode mode;
+ int pos;
};
/**
@@ -351,6 +360,8 @@ struct cxl_region_params {
int interleave_ways;
int interleave_granularity;
struct resource *res;
+ struct cxl_endpoint_decoder *targets[CXL_DECODER_MAX_INTERLEAVE];
+ int nr_targets;
};
/**