cxl/region: Add volatile region creation support

Expand the region creation infrastructure to enable 'ram'
(volatile-memory) regions. The internals of create_pmem_region_store()
and create_pmem_region_show() are factored out into helpers
__create_region() and __create_region_show() for the 'ram' case to
reuse.

Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>
Reviewed-by: Gregory Price <gregory.price@memverge.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Tested-by: Fan Ni <fan.ni@samsung.com>
Link: https://lore.kernel.org/r/167601995775.1924368.352616146815830591.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl
index 4c4e1cbb116901bf17adbba7236fa46b4f05e287..3acf2f17a73fe6d5c02afa0185524dd8ddcbefeb 100644 (file)
--- a/Documentation/ABI/testing/sysfs-bus-cxl
+++ b/Documentation/ABI/testing/sysfs-bus-cxl
@@ -285,20 +285,20 @@ Description:
                interleave_granularity).
 
 
-What:          /sys/bus/cxl/devices/decoderX.Y/create_pmem_region
-Date:          May, 2022
-KernelVersion: v6.0
+What:          /sys/bus/cxl/devices/decoderX.Y/create_{pmem,ram}_region
+Date:          May, 2022, January, 2023
+KernelVersion: v6.0 (pmem), v6.3 (ram)
 Contact:       linux-cxl@vger.kernel.org
 Description:
                (RW) Write a string in the form 'regionZ' to start the process
-               of defining a new persistent memory region (interleave-set)
-               within the decode range bounded by root decoder 'decoderX.Y'.
-               The value written must match the current value returned from
-               reading this attribute. An atomic compare exchange operation is
-               done on write to assign the requested id to a region and
-               allocate the region-id for the next creation attempt. EBUSY is
-               returned if the region name written does not match the current
-               cached value.
+               of defining a new persistent, or volatile memory region
+               (interleave-set) within the decode range bounded by root decoder
+               'decoderX.Y'. The value written must match the current value
+               returned from reading this attribute. An atomic compare exchange
+               operation is done on write to assign the requested id to a
+               region and allocate the region-id for the next creation attempt.
+               EBUSY is returned if the region name written does not match the
+               current cached value.
 
 
 What:          /sys/bus/cxl/devices/decoderX.Y/delete_region

diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index 8c04672dca5637f3de8149397c4f3494287a13d6..5eb873da5a30734f0e6821672acef55943ab258b 100644 (file)
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -11,6 +11,7 @@ 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_create_ram_region;
 extern struct device_attribute dev_attr_delete_region;
 extern struct device_attribute dev_attr_region;
 extern const struct device_type cxl_pmem_region_type;

diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index 1e541956f60550a6ce89ff541b5050952df8e2c3..9e5df64ea6b5250129141502f71f99194a8b1cd2 100644 (file)
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -294,6 +294,7 @@ static struct attribute *cxl_decoder_root_attrs[] = {
        &dev_attr_cap_type3.attr,
        &dev_attr_target_list.attr,
        SET_CXL_REGION_ATTR(create_pmem_region)
+       SET_CXL_REGION_ATTR(create_ram_region)
        SET_CXL_REGION_ATTR(delete_region)
        NULL,
 };
@@ -305,6 +306,13 @@ static bool can_create_pmem(struct cxl_root_decoder *cxlrd)
        return (cxlrd->cxlsd.cxld.flags & flags) == flags;
 }
 
+static bool can_create_ram(struct cxl_root_decoder *cxlrd)
+{
+       unsigned long flags = CXL_DECODER_F_TYPE3 | CXL_DECODER_F_RAM;
+
+       return (cxlrd->cxlsd.cxld.flags & flags) == flags;
+}
+
 static umode_t cxl_root_decoder_visible(struct kobject *kobj, struct attribute *a, int n)
 {
        struct device *dev = kobj_to_dev(kobj);
@@ -313,7 +321,11 @@ static umode_t cxl_root_decoder_visible(struct kobject *kobj, struct attribute *
        if (a == CXL_REGION_ATTR(create_pmem_region) && !can_create_pmem(cxlrd))
                return 0;
 
-       if (a == CXL_REGION_ATTR(delete_region) && !can_create_pmem(cxlrd))
+       if (a == CXL_REGION_ATTR(create_ram_region) && !can_create_ram(cxlrd))
+               return 0;
+
+       if (a == CXL_REGION_ATTR(delete_region) &&
+           !(can_create_pmem(cxlrd) || can_create_ram(cxlrd)))
                return 0;
 
        return a->mode;

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 285835145e9b4106c08070bf2d957cb1b8c6e10e..e440db8611a41cebea61c78e12b1d3b85da603f0 100644 (file)
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -1689,6 +1689,15 @@ static struct cxl_region *devm_cxl_add_region(struct cxl_root_decoder *cxlrd,
        struct device *dev;
        int rc;
 
+       switch (mode) {
+       case CXL_DECODER_RAM:
+       case CXL_DECODER_PMEM:
+               break;
+       default:
+               dev_err(&cxlrd->cxlsd.cxld.dev, "unsupported mode %d\n", mode);
+               return ERR_PTR(-EINVAL);
+       }
+
        cxlr = cxl_region_alloc(cxlrd, id);
        if (IS_ERR(cxlr))
                return cxlr;
@@ -1717,12 +1726,38 @@ err:
        return ERR_PTR(rc);
 }
 
+static ssize_t __create_region_show(struct cxl_root_decoder *cxlrd, char *buf)
+{
+       return sysfs_emit(buf, "region%u\n", atomic_read(&cxlrd->region_id));
+}
+
 static ssize_t create_pmem_region_show(struct device *dev,
                                       struct device_attribute *attr, char *buf)
 {
-       struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(dev);
+       return __create_region_show(to_cxl_root_decoder(dev), buf);
+}
 
-       return sysfs_emit(buf, "region%u\n", atomic_read(&cxlrd->region_id));
+static ssize_t create_ram_region_show(struct device *dev,
+                                     struct device_attribute *attr, char *buf)
+{
+       return __create_region_show(to_cxl_root_decoder(dev), buf);
+}
+
+static struct cxl_region *__create_region(struct cxl_root_decoder *cxlrd,
+                                         enum cxl_decoder_mode mode, int id)
+{
+       int rc;
+
+       rc = memregion_alloc(GFP_KERNEL);
+       if (rc < 0)
+               return ERR_PTR(rc);
+
+       if (atomic_cmpxchg(&cxlrd->region_id, id, rc) != id) {
+               memregion_free(rc);
+               return ERR_PTR(-EBUSY);
+       }
+
+       return devm_cxl_add_region(cxlrd, id, mode, CXL_DECODER_EXPANDER);
 }
 
 static ssize_t create_pmem_region_store(struct device *dev,
@@ -1731,29 +1766,39 @@ static ssize_t create_pmem_region_store(struct device *dev,
 {
        struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(dev);
        struct cxl_region *cxlr;
-       int id, rc;
+       int rc, id;
 
        rc = sscanf(buf, "region%d\n", &id);
        if (rc != 1)
                return -EINVAL;
 
-       rc = memregion_alloc(GFP_KERNEL);
-       if (rc < 0)
-               return rc;
+       cxlr = __create_region(cxlrd, CXL_DECODER_PMEM, id);
+       if (IS_ERR(cxlr))
+               return PTR_ERR(cxlr);
 
-       if (atomic_cmpxchg(&cxlrd->region_id, id, rc) != id) {
-               memregion_free(rc);
-               return -EBUSY;
-       }
+       return len;
+}
+DEVICE_ATTR_RW(create_pmem_region);
+
+static ssize_t create_ram_region_store(struct device *dev,
+                                      struct device_attribute *attr,
+                                      const char *buf, size_t len)
+{
+       struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(dev);
+       struct cxl_region *cxlr;
+       int rc, id;
 
-       cxlr = devm_cxl_add_region(cxlrd, id, CXL_DECODER_PMEM,
-                                  CXL_DECODER_EXPANDER);
+       rc = sscanf(buf, "region%d\n", &id);
+       if (rc != 1)
+               return -EINVAL;
+
+       cxlr = __create_region(cxlrd, CXL_DECODER_RAM, id);
        if (IS_ERR(cxlr))
                return PTR_ERR(cxlr);
 
        return len;
 }
-DEVICE_ATTR_RW(create_pmem_region);
+DEVICE_ATTR_RW(create_ram_region);
 
 static ssize_t region_show(struct device *dev, struct device_attribute *attr,
                           char *buf)