diff mbox series

[v5,22/27] cxl: allow region creation by type2 drivers

Message ID 20241118164434.7551-23-alejandro.lucero-palau@amd.com (mailing list archive)
State Not Applicable
Headers show
Series cxl: add type2 device basic support | expand

Checks

Context Check Description
netdev/series_format fail Series longer than 15 patches
netdev/tree_selection success Guessed tree name to be net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit fail Errors and warnings before: 12 this patch: 12
netdev/build_tools success Errors and warnings before: 0 (+0) this patch: 0 (+0)
netdev/cc_maintainers warning 6 maintainers not CCed: alison.schofield@intel.com dave.jiang@intel.com dave@stgolabs.net jonathan.cameron@huawei.com ira.weiny@intel.com vishal.l.verma@intel.com
netdev/build_clang success Errors and warnings before: 9 this patch: 9
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 10 this patch: 10
netdev/checkpatch warning WARNING: line length of 84 exceeds 80 columns
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc fail Errors and warnings before: 4 this patch: 5
netdev/source_inline success Was 0 now: 0

Commit Message

Lucero Palau, Alejandro Nov. 18, 2024, 4:44 p.m. UTC 
From: Alejandro Lucero <alucerop@amd.com>

Creating a CXL region requires userspace intervention through the cxl
sysfs files. Type2 support should allow accelerator drivers to create
such cxl region from kernel code.

Adding that functionality and integrating it with current support for
memory expanders.

Based on https://lore.kernel.org/linux-cxl/168592159835.1948938.1647215579839222774.stgit@dwillia2-xfh.jf.intel.com/

Signed-off-by: Alejandro Lucero <alucerop@amd.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/cxl/core/region.c | 147 ++++++++++++++++++++++++++++++++++----
 drivers/cxl/cxlmem.h      |   2 +
 drivers/cxl/port.c        |   5 +-
 include/cxl/cxl.h         |   4 ++
 4 files changed, 142 insertions(+), 16 deletions(-)

Comments

Zhi Wang Nov. 19, 2024, 8:37 p.m. UTC | #1 
On Mon, 18 Nov 2024 16:44:29 +0000
<alejandro.lucero-palau@amd.com> wrote:

> From: Alejandro Lucero <alucerop@amd.com>
> 
> Creating a CXL region requires userspace intervention through the cxl
> sysfs files. Type2 support should allow accelerator drivers to create
> such cxl region from kernel code.
> 
> Adding that functionality and integrating it with current support for
> memory expanders.
> 
> Based on https://lore.kernel.org/linux-cxl/168592159835.1948938.1647215579839222774.stgit@dwillia2-xfh.jf.intel.com/
> 
> Signed-off-by: Alejandro Lucero <alucerop@amd.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
>  drivers/cxl/core/region.c | 147 ++++++++++++++++++++++++++++++++++----
>  drivers/cxl/cxlmem.h      |   2 +
>  drivers/cxl/port.c        |   5 +-
>  include/cxl/cxl.h         |   4 ++
>  4 files changed, 142 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 6652887ea396..70549d42c2e3 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -2256,6 +2256,18 @@ static int cxl_region_detach(struct cxl_endpoint_decoder *cxled)
>  	return rc;
>  }
>  
> +int cxl_accel_region_detach(struct cxl_endpoint_decoder *cxled)
> +{
> +	int rc;
> +
> +	down_write(&cxl_region_rwsem);
> +	cxled->mode = CXL_DECODER_DEAD;
> +	rc = cxl_region_detach(cxled);
> +	up_write(&cxl_region_rwsem);
> +	return rc;
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_accel_region_detach, CXL);
> +
>  void cxl_decoder_kill_region(struct cxl_endpoint_decoder *cxled)
>  {
>  	down_write(&cxl_region_rwsem);
> @@ -2770,6 +2782,14 @@ cxl_find_region_by_name(struct cxl_root_decoder *cxlrd, const char *name)
>  	return to_cxl_region(region_dev);
>  }
>  
> +static void drop_region(struct cxl_region *cxlr)
> +{
> +	struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(cxlr->dev.parent);
> +	struct cxl_port *port = cxlrd_to_port(cxlrd);
> +
> +	devm_release_action(port->uport_dev, unregister_region, cxlr);
> +}
> +
>  static ssize_t delete_region_store(struct device *dev,
>  				   struct device_attribute *attr,
>  				   const char *buf, size_t len)
> @@ -3376,17 +3396,18 @@ static int match_region_by_range(struct device *dev, void *data)
>  	return rc;
>  }
>  
> -/* Establish an empty region covering the given HPA range */
> -static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
> -					   struct cxl_endpoint_decoder *cxled)
> +static void construct_region_end(void)
> +{
> +	up_write(&cxl_region_rwsem);
> +}
> +
> +static struct cxl_region *construct_region_begin(struct cxl_root_decoder *cxlrd,
> +						 struct cxl_endpoint_decoder *cxled)
>  {
>  	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
> -	struct cxl_port *port = cxlrd_to_port(cxlrd);
> -	struct range *hpa = &cxled->cxld.hpa_range;
>  	struct cxl_region_params *p;
>  	struct cxl_region *cxlr;
> -	struct resource *res;
> -	int rc;
> +	int err;

maybe let's keep the original name "rc".
>  
>  	do {
>  		cxlr = __create_region(cxlrd, cxled->mode,
> @@ -3395,8 +3416,7 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
>  	} while (IS_ERR(cxlr) && PTR_ERR(cxlr) == -EBUSY);
>  
>  	if (IS_ERR(cxlr)) {
> -		dev_err(cxlmd->dev.parent,
> -			"%s:%s: %s failed assign region: %ld\n",
> +		dev_err(cxlmd->dev.parent, "%s:%s: %s failed assign region: %ld\n",
>  			dev_name(&cxlmd->dev), dev_name(&cxled->cxld.dev),
>  			__func__, PTR_ERR(cxlr));
>  		return cxlr;
> @@ -3406,13 +3426,33 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
>  	p = &cxlr->params;
>  	if (p->state >= CXL_CONFIG_INTERLEAVE_ACTIVE) {
>  		dev_err(cxlmd->dev.parent,
> -			"%s:%s: %s autodiscovery interrupted\n",
> +			"%s:%s: %s region setup interrupted\n",
>  			dev_name(&cxlmd->dev), dev_name(&cxled->cxld.dev),
>  			__func__);
> -		rc = -EBUSY;
> -		goto err;
> +		err = -EBUSY;
> +		construct_region_end();
> +		drop_region(cxlr);
> +		return ERR_PTR(err);
>  	}
>  
> +	return cxlr;
> +}
> +
> +/* Establish an empty region covering the given HPA range */
> +static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
> +					   struct cxl_endpoint_decoder *cxled)
> +{
> +	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
> +	struct range *hpa = &cxled->cxld.hpa_range;
> +	struct cxl_region_params *p;
> +	struct cxl_region *cxlr;
> +	struct resource *res;
> +	int rc;
> +
> +	cxlr = construct_region_begin(cxlrd, cxled);
> +	if (IS_ERR(cxlr))
> +		return cxlr;
> +
>  	set_bit(CXL_REGION_F_AUTO, &cxlr->flags);
>  
>  	res = kmalloc(sizeof(*res), GFP_KERNEL);
> @@ -3435,6 +3475,7 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
>  			 __func__, dev_name(&cxlr->dev));
>  	}
>  
> +	p = &cxlr->params;
>  	p->res = res;
>  	p->interleave_ways = cxled->cxld.interleave_ways;
>  	p->interleave_granularity = cxled->cxld.interleave_granularity;
> @@ -3452,15 +3493,91 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
>  	/* ...to match put_device() in cxl_add_to_region() */
>  	get_device(&cxlr->dev);
>  	up_write(&cxl_region_rwsem);
> -
> +	construct_region_end();

cxl_region_rwsem seems got up_write() two times. Guess you should remove
it like below since it is now done in construct_region_end().

>  	return cxlr;
>  
>  err:
> -	up_write(&cxl_region_rwsem);
> -	devm_release_action(port->uport_dev, unregister_region, cxlr);
> +	construct_region_end();
> +	drop_region(cxlr);
> +	return ERR_PTR(rc);
> +}
> +
> +static struct cxl_region *
> +__construct_new_region(struct cxl_root_decoder *cxlrd,
> +		       struct cxl_endpoint_decoder *cxled)
> +{
> +	struct cxl_decoder *cxld = &cxlrd->cxlsd.cxld;
> +	struct cxl_region_params *p;
> +	struct cxl_region *cxlr;
> +	int rc;
> +
> +	cxlr = construct_region_begin(cxlrd, cxled);
> +	if (IS_ERR(cxlr))
> +		return cxlr;
> +
> +	rc = set_interleave_ways(cxlr, 1);
> +	if (rc)
> +		goto err;
> +
> +	rc = set_interleave_granularity(cxlr, cxld->interleave_granularity);
> +	if (rc)
> +		goto err;
> +
> +	rc = alloc_hpa(cxlr, resource_size(cxled->dpa_res));
> +	if (rc)
> +		goto err;
> +
> +	down_read(&cxl_dpa_rwsem);
> +	rc = cxl_region_attach(cxlr, cxled, 0);
> +	up_read(&cxl_dpa_rwsem);
> +
> +	if (rc)
> +		goto err;
> +
> +	rc = cxl_region_decode_commit(cxlr);
> +	if (rc)
> +		goto err;
> +
> +	p = &cxlr->params;
> +	p->state = CXL_CONFIG_COMMIT;
> +
> +	construct_region_end();
> +	return cxlr;
> +err:
> +	construct_region_end();
> +	drop_region(cxlr);
>  	return ERR_PTR(rc);
>  }
>  
> +/**
> + * cxl_create_region - Establish a region given an endpoint decoder
> + * @cxlrd: root decoder to allocate HPA
> + * @cxled: endpoint decoder with reserved DPA capacity
> + *
> + * Returns a fully formed region in the commit state and attached to the
> + * cxl_region driver.
> + */
> +struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
> +				     struct cxl_endpoint_decoder *cxled)
> +{
> +	struct cxl_region *cxlr;
> +
> +	mutex_lock(&cxlrd->range_lock);
> +	cxlr = __construct_new_region(cxlrd, cxled);
> +	mutex_unlock(&cxlrd->range_lock);
> +
> +	if (IS_ERR(cxlr))
> +		return cxlr;
> +
> +	if (device_attach(&cxlr->dev) <= 0) {
> +		dev_err(&cxlr->dev, "failed to create region\n");
> +		drop_region(cxlr);
> +		return ERR_PTR(-ENODEV);
> +	}
> +	return cxlr;
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_create_region, CXL);
> +
>  int cxl_add_to_region(struct cxl_port *root, struct cxl_endpoint_decoder *cxled)
>  {
>  	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
> diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
> index 4c1c53c29544..9d874f1cb3bf 100644
> --- a/drivers/cxl/cxlmem.h
> +++ b/drivers/cxl/cxlmem.h
> @@ -874,4 +874,6 @@ struct cxl_hdm {
>  struct seq_file;
>  struct dentry *cxl_debugfs_create_dir(const char *dir);
>  void cxl_dpa_debug(struct seq_file *file, struct cxl_dev_state *cxlds);
> +struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
> +				     struct cxl_endpoint_decoder *cxled);
>  #endif /* __CXL_MEM_H__ */
> diff --git a/drivers/cxl/port.c b/drivers/cxl/port.c
> index acf2ac70f343..ec1f0cfb11a5 100644
> --- a/drivers/cxl/port.c
> +++ b/drivers/cxl/port.c
> @@ -33,6 +33,7 @@ static void schedule_detach(void *cxlmd)
>  static int discover_region(struct device *dev, void *root)
>  {
>  	struct cxl_endpoint_decoder *cxled;
> +	struct cxl_memdev *cxlmd;
>  	int rc;
>  
>  	if (!is_endpoint_decoder(dev))
> @@ -42,7 +43,9 @@ static int discover_region(struct device *dev, void *root)
>  	if ((cxled->cxld.flags & CXL_DECODER_F_ENABLE) == 0)
>  		return 0;
>  
> -	if (cxled->state != CXL_DECODER_STATE_AUTO)
> +	cxlmd = cxled_to_memdev(cxled);
> +	if (cxled->state != CXL_DECODER_STATE_AUTO ||
> +	    cxlmd->cxlds->type == CXL_DEVTYPE_DEVMEM)
>  		return 0;
>  
>  	/*
> diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h
> index 9b5b5472a86b..d295af4f5f9e 100644
> --- a/include/cxl/cxl.h
> +++ b/include/cxl/cxl.h
> @@ -72,4 +72,8 @@ struct cxl_endpoint_decoder *cxl_request_dpa(struct cxl_memdev *cxlmd,
>  					     resource_size_t min,
>  					     resource_size_t max);
>  int cxl_dpa_free(struct cxl_endpoint_decoder *cxled);
> +struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
> +				     struct cxl_endpoint_decoder *cxled);
> +
> +int cxl_accel_region_detach(struct cxl_endpoint_decoder *cxled);
>  #endif
Alejandro Lucero Palau Nov. 20, 2024, 1:51 p.m. UTC | #2 
On 11/19/24 20:37, Zhi Wang wrote:
> On Mon, 18 Nov 2024 16:44:29 +0000
> <alejandro.lucero-palau@amd.com> wrote:
>
>> From: Alejandro Lucero <alucerop@amd.com>
>>
<snip>
>>   
>> -/* Establish an empty region covering the given HPA range */
>> -static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
>> -					   struct cxl_endpoint_decoder *cxled)
>> +static void construct_region_end(void)
>> +{
>> +	up_write(&cxl_region_rwsem);
>> +}
>> +
>> +static struct cxl_region *construct_region_begin(struct cxl_root_decoder *cxlrd,
>> +						 struct cxl_endpoint_decoder *cxled)
>>   {
>>   	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
>> -	struct cxl_port *port = cxlrd_to_port(cxlrd);
>> -	struct range *hpa = &cxled->cxld.hpa_range;
>>   	struct cxl_region_params *p;
>>   	struct cxl_region *cxlr;
>> -	struct resource *res;
>> -	int rc;
>> +	int err;
> maybe let's keep the original name "rc".


Note this is a new function. It comes straight from original Dan's 
patch, and I think he changed that as there is another function doing 
the "return call" which invokes this one as part of the call.


>>   
>>   	do {
>>   		cxlr = __create_region(cxlrd, cxled->mode,
>> @@ -3395,8 +3416,7 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
>>   	} while (IS_ERR(cxlr) && PTR_ERR(cxlr) == -EBUSY);
>>   
>>   	if (IS_ERR(cxlr)) {
>> -		dev_err(cxlmd->dev.parent,
>> -			"%s:%s: %s failed assign region: %ld\n",
>> +		dev_err(cxlmd->dev.parent, "%s:%s: %s failed assign region: %ld\n",
>>   			dev_name(&cxlmd->dev), dev_name(&cxled->cxld.dev),
>>   			__func__, PTR_ERR(cxlr));
>>   		return cxlr;
>> @@ -3406,13 +3426,33 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
>>   	p = &cxlr->params;
>>   	if (p->state >= CXL_CONFIG_INTERLEAVE_ACTIVE) {
>>   		dev_err(cxlmd->dev.parent,
>> -			"%s:%s: %s autodiscovery interrupted\n",
>> +			"%s:%s: %s region setup interrupted\n",
>>   			dev_name(&cxlmd->dev), dev_name(&cxled->cxld.dev),
>>   			__func__);
>> -		rc = -EBUSY;
>> -		goto err;
>> +		err = -EBUSY;
>> +		construct_region_end();
>> +		drop_region(cxlr);
>> +		return ERR_PTR(err);
>>   	}
>>   
>> +	return cxlr;
>> +}
>> +
>> +/* Establish an empty region covering the given HPA range */
>> +static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
>> +					   struct cxl_endpoint_decoder *cxled)
>> +{
>> +	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
>> +	struct range *hpa = &cxled->cxld.hpa_range;
>> +	struct cxl_region_params *p;
>> +	struct cxl_region *cxlr;
>> +	struct resource *res;
>> +	int rc;
>> +
>> +	cxlr = construct_region_begin(cxlrd, cxled);
>> +	if (IS_ERR(cxlr))
>> +		return cxlr;
>> +
>>   	set_bit(CXL_REGION_F_AUTO, &cxlr->flags);
>>   
>>   	res = kmalloc(sizeof(*res), GFP_KERNEL);
>> @@ -3435,6 +3475,7 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
>>   			 __func__, dev_name(&cxlr->dev));
>>   	}
>>   
>> +	p = &cxlr->params;
>>   	p->res = res;
>>   	p->interleave_ways = cxled->cxld.interleave_ways;
>>   	p->interleave_granularity = cxled->cxld.interleave_granularity;
>> @@ -3452,15 +3493,91 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
>>   	/* ...to match put_device() in cxl_add_to_region() */
>>   	get_device(&cxlr->dev);
>>   	up_write(&cxl_region_rwsem);
>> -
>> +	construct_region_end();
> cxl_region_rwsem seems got up_write() two times. Guess you should remove
> it like below since it is now done in construct_region_end().



You are right. I think I messed up that with the code below for handling 
a potential error.

I'll fix it.

Good catch!


>>   	return cxlr;
>>   
>>   err:
>> -	up_write(&cxl_region_rwsem);
>> -	devm_release_action(port->uport_dev, unregister_region, cxlr);
>> +	construct_region_end();
>> +	drop_region(cxlr);
>> +	return ERR_PTR(rc);
>> +}
>> +
diff mbox series

Patch

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 6652887ea396..70549d42c2e3 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -2256,6 +2256,18 @@  static int cxl_region_detach(struct cxl_endpoint_decoder *cxled)
 	return rc;
 }
 
+int cxl_accel_region_detach(struct cxl_endpoint_decoder *cxled)
+{
+	int rc;
+
+	down_write(&cxl_region_rwsem);
+	cxled->mode = CXL_DECODER_DEAD;
+	rc = cxl_region_detach(cxled);
+	up_write(&cxl_region_rwsem);
+	return rc;
+}
+EXPORT_SYMBOL_NS_GPL(cxl_accel_region_detach, CXL);
+
 void cxl_decoder_kill_region(struct cxl_endpoint_decoder *cxled)
 {
 	down_write(&cxl_region_rwsem);
@@ -2770,6 +2782,14 @@  cxl_find_region_by_name(struct cxl_root_decoder *cxlrd, const char *name)
 	return to_cxl_region(region_dev);
 }
 
+static void drop_region(struct cxl_region *cxlr)
+{
+	struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(cxlr->dev.parent);
+	struct cxl_port *port = cxlrd_to_port(cxlrd);
+
+	devm_release_action(port->uport_dev, unregister_region, cxlr);
+}
+
 static ssize_t delete_region_store(struct device *dev,
 				   struct device_attribute *attr,
 				   const char *buf, size_t len)
@@ -3376,17 +3396,18 @@  static int match_region_by_range(struct device *dev, void *data)
 	return rc;
 }
 
-/* Establish an empty region covering the given HPA range */
-static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
-					   struct cxl_endpoint_decoder *cxled)
+static void construct_region_end(void)
+{
+	up_write(&cxl_region_rwsem);
+}
+
+static struct cxl_region *construct_region_begin(struct cxl_root_decoder *cxlrd,
+						 struct cxl_endpoint_decoder *cxled)
 {
 	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
-	struct cxl_port *port = cxlrd_to_port(cxlrd);
-	struct range *hpa = &cxled->cxld.hpa_range;
 	struct cxl_region_params *p;
 	struct cxl_region *cxlr;
-	struct resource *res;
-	int rc;
+	int err;
 
 	do {
 		cxlr = __create_region(cxlrd, cxled->mode,
@@ -3395,8 +3416,7 @@  static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
 	} while (IS_ERR(cxlr) && PTR_ERR(cxlr) == -EBUSY);
 
 	if (IS_ERR(cxlr)) {
-		dev_err(cxlmd->dev.parent,
-			"%s:%s: %s failed assign region: %ld\n",
+		dev_err(cxlmd->dev.parent, "%s:%s: %s failed assign region: %ld\n",
 			dev_name(&cxlmd->dev), dev_name(&cxled->cxld.dev),
 			__func__, PTR_ERR(cxlr));
 		return cxlr;
@@ -3406,13 +3426,33 @@  static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
 	p = &cxlr->params;
 	if (p->state >= CXL_CONFIG_INTERLEAVE_ACTIVE) {
 		dev_err(cxlmd->dev.parent,
-			"%s:%s: %s autodiscovery interrupted\n",
+			"%s:%s: %s region setup interrupted\n",
 			dev_name(&cxlmd->dev), dev_name(&cxled->cxld.dev),
 			__func__);
-		rc = -EBUSY;
-		goto err;
+		err = -EBUSY;
+		construct_region_end();
+		drop_region(cxlr);
+		return ERR_PTR(err);
 	}
 
+	return cxlr;
+}
+
+/* Establish an empty region covering the given HPA range */
+static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
+					   struct cxl_endpoint_decoder *cxled)
+{
+	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
+	struct range *hpa = &cxled->cxld.hpa_range;
+	struct cxl_region_params *p;
+	struct cxl_region *cxlr;
+	struct resource *res;
+	int rc;
+
+	cxlr = construct_region_begin(cxlrd, cxled);
+	if (IS_ERR(cxlr))
+		return cxlr;
+
 	set_bit(CXL_REGION_F_AUTO, &cxlr->flags);
 
 	res = kmalloc(sizeof(*res), GFP_KERNEL);
@@ -3435,6 +3475,7 @@  static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
 			 __func__, dev_name(&cxlr->dev));
 	}
 
+	p = &cxlr->params;
 	p->res = res;
 	p->interleave_ways = cxled->cxld.interleave_ways;
 	p->interleave_granularity = cxled->cxld.interleave_granularity;
@@ -3452,15 +3493,91 @@  static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
 	/* ...to match put_device() in cxl_add_to_region() */
 	get_device(&cxlr->dev);
 	up_write(&cxl_region_rwsem);
-
+	construct_region_end();
 	return cxlr;
 
 err:
-	up_write(&cxl_region_rwsem);
-	devm_release_action(port->uport_dev, unregister_region, cxlr);
+	construct_region_end();
+	drop_region(cxlr);
+	return ERR_PTR(rc);
+}
+
+static struct cxl_region *
+__construct_new_region(struct cxl_root_decoder *cxlrd,
+		       struct cxl_endpoint_decoder *cxled)
+{
+	struct cxl_decoder *cxld = &cxlrd->cxlsd.cxld;
+	struct cxl_region_params *p;
+	struct cxl_region *cxlr;
+	int rc;
+
+	cxlr = construct_region_begin(cxlrd, cxled);
+	if (IS_ERR(cxlr))
+		return cxlr;
+
+	rc = set_interleave_ways(cxlr, 1);
+	if (rc)
+		goto err;
+
+	rc = set_interleave_granularity(cxlr, cxld->interleave_granularity);
+	if (rc)
+		goto err;
+
+	rc = alloc_hpa(cxlr, resource_size(cxled->dpa_res));
+	if (rc)
+		goto err;
+
+	down_read(&cxl_dpa_rwsem);
+	rc = cxl_region_attach(cxlr, cxled, 0);
+	up_read(&cxl_dpa_rwsem);
+
+	if (rc)
+		goto err;
+
+	rc = cxl_region_decode_commit(cxlr);
+	if (rc)
+		goto err;
+
+	p = &cxlr->params;
+	p->state = CXL_CONFIG_COMMIT;
+
+	construct_region_end();
+	return cxlr;
+err:
+	construct_region_end();
+	drop_region(cxlr);
 	return ERR_PTR(rc);
 }
 
+/**
+ * cxl_create_region - Establish a region given an endpoint decoder
+ * @cxlrd: root decoder to allocate HPA
+ * @cxled: endpoint decoder with reserved DPA capacity
+ *
+ * Returns a fully formed region in the commit state and attached to the
+ * cxl_region driver.
+ */
+struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
+				     struct cxl_endpoint_decoder *cxled)
+{
+	struct cxl_region *cxlr;
+
+	mutex_lock(&cxlrd->range_lock);
+	cxlr = __construct_new_region(cxlrd, cxled);
+	mutex_unlock(&cxlrd->range_lock);
+
+	if (IS_ERR(cxlr))
+		return cxlr;
+
+	if (device_attach(&cxlr->dev) <= 0) {
+		dev_err(&cxlr->dev, "failed to create region\n");
+		drop_region(cxlr);
+		return ERR_PTR(-ENODEV);
+	}
+	return cxlr;
+}
+EXPORT_SYMBOL_NS_GPL(cxl_create_region, CXL);
+
 int cxl_add_to_region(struct cxl_port *root, struct cxl_endpoint_decoder *cxled)
 {
 	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
index 4c1c53c29544..9d874f1cb3bf 100644
--- a/drivers/cxl/cxlmem.h
+++ b/drivers/cxl/cxlmem.h
@@ -874,4 +874,6 @@  struct cxl_hdm {
 struct seq_file;
 struct dentry *cxl_debugfs_create_dir(const char *dir);
 void cxl_dpa_debug(struct seq_file *file, struct cxl_dev_state *cxlds);
+struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
+				     struct cxl_endpoint_decoder *cxled);
 #endif /* __CXL_MEM_H__ */
diff --git a/drivers/cxl/port.c b/drivers/cxl/port.c
index acf2ac70f343..ec1f0cfb11a5 100644
--- a/drivers/cxl/port.c
+++ b/drivers/cxl/port.c
@@ -33,6 +33,7 @@  static void schedule_detach(void *cxlmd)
 static int discover_region(struct device *dev, void *root)
 {
 	struct cxl_endpoint_decoder *cxled;
+	struct cxl_memdev *cxlmd;
 	int rc;
 
 	if (!is_endpoint_decoder(dev))
@@ -42,7 +43,9 @@  static int discover_region(struct device *dev, void *root)
 	if ((cxled->cxld.flags & CXL_DECODER_F_ENABLE) == 0)
 		return 0;
 
-	if (cxled->state != CXL_DECODER_STATE_AUTO)
+	cxlmd = cxled_to_memdev(cxled);
+	if (cxled->state != CXL_DECODER_STATE_AUTO ||
+	    cxlmd->cxlds->type == CXL_DEVTYPE_DEVMEM)
 		return 0;
 
 	/*
diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h
index 9b5b5472a86b..d295af4f5f9e 100644
--- a/include/cxl/cxl.h
+++ b/include/cxl/cxl.h
@@ -72,4 +72,8 @@  struct cxl_endpoint_decoder *cxl_request_dpa(struct cxl_memdev *cxlmd,
 					     resource_size_t min,
 					     resource_size_t max);
 int cxl_dpa_free(struct cxl_endpoint_decoder *cxled);
+struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
+				     struct cxl_endpoint_decoder *cxled);
+
+int cxl_accel_region_detach(struct cxl_endpoint_decoder *cxled);
 #endif