diff mbox series

[v5,24/27] cxl: add region flag for precluding a device memory to be used for dax

Message ID 20241118164434.7551-25-alejandro.lucero-palau@amd.com
State New
Headers show
Series cxl: add type2 device basic support | expand

Commit Message

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

By definition a type2 cxl device will use the host managed memory for
specific functionality, therefore it should not be available to other
uses. However, a dax interface could be just good enough in some cases.

Add a flag to a cxl region for specifically state to not create a dax
device. Allow a Type2 driver to set that flag at region creation time.

Signed-off-by: Alejandro Lucero <alucerop@amd.com>
---
 drivers/cxl/core/region.c | 10 +++++++++-
 drivers/cxl/cxl.h         |  3 +++
 drivers/cxl/cxlmem.h      |  3 ++-
 include/cxl/cxl.h         |  3 ++-
 4 files changed, 16 insertions(+), 3 deletions(-)

Comments

Zhi Wang Nov. 19, 2024, 8:39 p.m. UTC | #1 
On Mon, 18 Nov 2024 16:44:31 +0000
<alejandro.lucero-palau@amd.com> wrote:

Minor comment: maybe no_dax would be better than "avoid dax".

> From: Alejandro Lucero <alucerop@amd.com>
> 
> By definition a type2 cxl device will use the host managed memory for
> specific functionality, therefore it should not be available to other
> uses. However, a dax interface could be just good enough in some cases.
> 
> Add a flag to a cxl region for specifically state to not create a dax
> device. Allow a Type2 driver to set that flag at region creation time.
> 
> Signed-off-by: Alejandro Lucero <alucerop@amd.com>
> ---
>  drivers/cxl/core/region.c | 10 +++++++++-
>  drivers/cxl/cxl.h         |  3 +++
>  drivers/cxl/cxlmem.h      |  3 ++-
>  include/cxl/cxl.h         |  3 ++-
>  4 files changed, 16 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 70549d42c2e3..eff3ad788077 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -3558,7 +3558,8 @@ __construct_new_region(struct cxl_root_decoder *cxlrd,
>   * cxl_region driver.
>   */
>  struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
> -				     struct cxl_endpoint_decoder *cxled)
> +				     struct cxl_endpoint_decoder *cxled,
> +				     bool avoid_dax)
>  {
>  	struct cxl_region *cxlr;
>  
> @@ -3574,6 +3575,10 @@ struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
>  		drop_region(cxlr);
>  		return ERR_PTR(-ENODEV);
>  	}
> +
> +	if (avoid_dax)
> +		set_bit(CXL_REGION_F_AVOID_DAX, &cxlr->flags);
> +
>  	return cxlr;
>  }
>  EXPORT_SYMBOL_NS_GPL(cxl_create_region, CXL);
> @@ -3713,6 +3718,9 @@ static int cxl_region_probe(struct device *dev)
>  	case CXL_DECODER_PMEM:
>  		return devm_cxl_add_pmem_region(cxlr);
>  	case CXL_DECODER_RAM:
> +		if (test_bit(CXL_REGION_F_AVOID_DAX, &cxlr->flags))
> +			return 0;
> +
>  		/*
>  		 * The region can not be manged by CXL if any portion of
>  		 * it is already online as 'System RAM'
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index 1e0e797b9303..ee3385db5663 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -512,6 +512,9 @@ struct cxl_region_params {
>   */
>  #define CXL_REGION_F_NEEDS_RESET 1
>  
> +/* Allow Type2 drivers to specify if a dax region should not be created. */
> +#define CXL_REGION_F_AVOID_DAX 2
> +
>  /**
>   * struct cxl_region - CXL region
>   * @dev: This region's device
> diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
> index 9d874f1cb3bf..cc2e2a295f3d 100644
> --- a/drivers/cxl/cxlmem.h
> +++ b/drivers/cxl/cxlmem.h
> @@ -875,5 +875,6 @@ 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);
> +				     struct cxl_endpoint_decoder *cxled,
> +				     bool avoid_dax);
>  #endif /* __CXL_MEM_H__ */
> diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h
> index d295af4f5f9e..2a8ebabfc1dd 100644
> --- a/include/cxl/cxl.h
> +++ b/include/cxl/cxl.h
> @@ -73,7 +73,8 @@ struct cxl_endpoint_decoder *cxl_request_dpa(struct cxl_memdev *cxlmd,
>  					     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);
> +				     struct cxl_endpoint_decoder *cxled,
> +				     bool avoid_dax);
>  
>  int cxl_accel_region_detach(struct cxl_endpoint_decoder *cxled);
>  #endif
Alejandro Lucero Palau Nov. 20, 2024, 1:55 p.m. UTC | #2 
On 11/19/24 20:39, Zhi Wang wrote:
> On Mon, 18 Nov 2024 16:44:31 +0000
> <alejandro.lucero-palau@amd.com> wrote:
>
> Minor comment: maybe no_dax would be better than "avoid dax".


It makes sense.

I'll do the change.

Thanks


>> From: Alejandro Lucero <alucerop@amd.com>
>>
>> By definition a type2 cxl device will use the host managed memory for
>> specific functionality, therefore it should not be available to other
>> uses. However, a dax interface could be just good enough in some cases.
>>
>> Add a flag to a cxl region for specifically state to not create a dax
>> device. Allow a Type2 driver to set that flag at region creation time.
>>
>> Signed-off-by: Alejandro Lucero <alucerop@amd.com>
>> ---
>>   drivers/cxl/core/region.c | 10 +++++++++-
>>   drivers/cxl/cxl.h         |  3 +++
>>   drivers/cxl/cxlmem.h      |  3 ++-
>>   include/cxl/cxl.h         |  3 ++-
>>   4 files changed, 16 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
>> index 70549d42c2e3..eff3ad788077 100644
>> --- a/drivers/cxl/core/region.c
>> +++ b/drivers/cxl/core/region.c
>> @@ -3558,7 +3558,8 @@ __construct_new_region(struct cxl_root_decoder *cxlrd,
>>    * cxl_region driver.
>>    */
>>   struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
>> -				     struct cxl_endpoint_decoder *cxled)
>> +				     struct cxl_endpoint_decoder *cxled,
>> +				     bool avoid_dax)
>>   {
>>   	struct cxl_region *cxlr;
>>   
>> @@ -3574,6 +3575,10 @@ struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
>>   		drop_region(cxlr);
>>   		return ERR_PTR(-ENODEV);
>>   	}
>> +
>> +	if (avoid_dax)
>> +		set_bit(CXL_REGION_F_AVOID_DAX, &cxlr->flags);
>> +
>>   	return cxlr;
>>   }
>>   EXPORT_SYMBOL_NS_GPL(cxl_create_region, CXL);
>> @@ -3713,6 +3718,9 @@ static int cxl_region_probe(struct device *dev)
>>   	case CXL_DECODER_PMEM:
>>   		return devm_cxl_add_pmem_region(cxlr);
>>   	case CXL_DECODER_RAM:
>> +		if (test_bit(CXL_REGION_F_AVOID_DAX, &cxlr->flags))
>> +			return 0;
>> +
>>   		/*
>>   		 * The region can not be manged by CXL if any portion of
>>   		 * it is already online as 'System RAM'
>> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
>> index 1e0e797b9303..ee3385db5663 100644
>> --- a/drivers/cxl/cxl.h
>> +++ b/drivers/cxl/cxl.h
>> @@ -512,6 +512,9 @@ struct cxl_region_params {
>>    */
>>   #define CXL_REGION_F_NEEDS_RESET 1
>>   
>> +/* Allow Type2 drivers to specify if a dax region should not be created. */
>> +#define CXL_REGION_F_AVOID_DAX 2
>> +
>>   /**
>>    * struct cxl_region - CXL region
>>    * @dev: This region's device
>> diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
>> index 9d874f1cb3bf..cc2e2a295f3d 100644
>> --- a/drivers/cxl/cxlmem.h
>> +++ b/drivers/cxl/cxlmem.h
>> @@ -875,5 +875,6 @@ 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);
>> +				     struct cxl_endpoint_decoder *cxled,
>> +				     bool avoid_dax);
>>   #endif /* __CXL_MEM_H__ */
>> diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h
>> index d295af4f5f9e..2a8ebabfc1dd 100644
>> --- a/include/cxl/cxl.h
>> +++ b/include/cxl/cxl.h
>> @@ -73,7 +73,8 @@ struct cxl_endpoint_decoder *cxl_request_dpa(struct cxl_memdev *cxlmd,
>>   					     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);
>> +				     struct cxl_endpoint_decoder *cxled,
>> +				     bool avoid_dax);
>>   
>>   int cxl_accel_region_detach(struct cxl_endpoint_decoder *cxled);
>>   #endif
Ben Cheatham Nov. 22, 2024, 8:46 p.m. UTC | #3 
On 11/18/24 10:44 AM, alejandro.lucero-palau@amd.com wrote:
> From: Alejandro Lucero <alucerop@amd.com>
> 
> By definition a type2 cxl device will use the host managed memory for
> specific functionality, therefore it should not be available to other
> uses. However, a dax interface could be just good enough in some cases.
> 
> Add a flag to a cxl region for specifically state to not create a dax
> device. Allow a Type2 driver to set that flag at region creation time.
> 
> Signed-off-by: Alejandro Lucero <alucerop@amd.com>
> ---
>  drivers/cxl/core/region.c | 10 +++++++++-
>  drivers/cxl/cxl.h         |  3 +++
>  drivers/cxl/cxlmem.h      |  3 ++-
>  include/cxl/cxl.h         |  3 ++-
>  4 files changed, 16 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 70549d42c2e3..eff3ad788077 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -3558,7 +3558,8 @@ __construct_new_region(struct cxl_root_decoder *cxlrd,
>   * cxl_region driver.
>   */
>  struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
> -				     struct cxl_endpoint_decoder *cxled)
> +				     struct cxl_endpoint_decoder *cxled,
> +				     bool avoid_dax)
>  {
>  	struct cxl_region *cxlr;
>  
> @@ -3574,6 +3575,10 @@ struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
>  		drop_region(cxlr);
>  		return ERR_PTR(-ENODEV);
>  	}
> +
> +	if (avoid_dax)
> +		set_bit(CXL_REGION_F_AVOID_DAX, &cxlr->flags);
> +
>  	return cxlr;
>  }
>  EXPORT_SYMBOL_NS_GPL(cxl_create_region, CXL);
> @@ -3713,6 +3718,9 @@ static int cxl_region_probe(struct device *dev)
>  	case CXL_DECODER_PMEM:
>  		return devm_cxl_add_pmem_region(cxlr);
>  	case CXL_DECODER_RAM:
> +		if (test_bit(CXL_REGION_F_AVOID_DAX, &cxlr->flags))
> +			return 0;

I think it's possible for a type 2 device to have pmem as well, and
it looks like these are the only two options at the moment, so I would
just move this check to before the switch statement.

> +
>  		/*
>  		 * The region can not be manged by CXL if any portion of
>  		 * it is already online as 'System RAM'
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index 1e0e797b9303..ee3385db5663 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -512,6 +512,9 @@ struct cxl_region_params {
>   */
>  #define CXL_REGION_F_NEEDS_RESET 1
>  
> +/* Allow Type2 drivers to specify if a dax region should not be created. */
> +#define CXL_REGION_F_AVOID_DAX 2
> +

I would like to see flags such that the device could choose the region type 
(system ram, device-dax, or none). I think that adding the ability
for device-dax would add a patch or two, so that may be a good follow up
patch.

>  /**
>   * struct cxl_region - CXL region
>   * @dev: This region's device
> diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
> index 9d874f1cb3bf..cc2e2a295f3d 100644
> --- a/drivers/cxl/cxlmem.h
> +++ b/drivers/cxl/cxlmem.h
> @@ -875,5 +875,6 @@ 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);
> +				     struct cxl_endpoint_decoder *cxled,
> +				     bool avoid_dax);
>  #endif /* __CXL_MEM_H__ */
> diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h
> index d295af4f5f9e..2a8ebabfc1dd 100644
> --- a/include/cxl/cxl.h
> +++ b/include/cxl/cxl.h
> @@ -73,7 +73,8 @@ struct cxl_endpoint_decoder *cxl_request_dpa(struct cxl_memdev *cxlmd,
>  					     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);
> +				     struct cxl_endpoint_decoder *cxled,
> +				     bool avoid_dax);
>  
>  int cxl_accel_region_detach(struct cxl_endpoint_decoder *cxled);
>  #endif
diff mbox series

Patch

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 70549d42c2e3..eff3ad788077 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -3558,7 +3558,8 @@  __construct_new_region(struct cxl_root_decoder *cxlrd,
  * cxl_region driver.
  */
 struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
-				     struct cxl_endpoint_decoder *cxled)
+				     struct cxl_endpoint_decoder *cxled,
+				     bool avoid_dax)
 {
 	struct cxl_region *cxlr;
 
@@ -3574,6 +3575,10 @@  struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
 		drop_region(cxlr);
 		return ERR_PTR(-ENODEV);
 	}
+
+	if (avoid_dax)
+		set_bit(CXL_REGION_F_AVOID_DAX, &cxlr->flags);
+
 	return cxlr;
 }
 EXPORT_SYMBOL_NS_GPL(cxl_create_region, CXL);
@@ -3713,6 +3718,9 @@  static int cxl_region_probe(struct device *dev)
 	case CXL_DECODER_PMEM:
 		return devm_cxl_add_pmem_region(cxlr);
 	case CXL_DECODER_RAM:
+		if (test_bit(CXL_REGION_F_AVOID_DAX, &cxlr->flags))
+			return 0;
+
 		/*
 		 * The region can not be manged by CXL if any portion of
 		 * it is already online as 'System RAM'
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 1e0e797b9303..ee3385db5663 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -512,6 +512,9 @@  struct cxl_region_params {
  */
 #define CXL_REGION_F_NEEDS_RESET 1
 
+/* Allow Type2 drivers to specify if a dax region should not be created. */
+#define CXL_REGION_F_AVOID_DAX 2
+
 /**
  * struct cxl_region - CXL region
  * @dev: This region's device
diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
index 9d874f1cb3bf..cc2e2a295f3d 100644
--- a/drivers/cxl/cxlmem.h
+++ b/drivers/cxl/cxlmem.h
@@ -875,5 +875,6 @@  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);
+				     struct cxl_endpoint_decoder *cxled,
+				     bool avoid_dax);
 #endif /* __CXL_MEM_H__ */
diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h
index d295af4f5f9e..2a8ebabfc1dd 100644
--- a/include/cxl/cxl.h
+++ b/include/cxl/cxl.h
@@ -73,7 +73,8 @@  struct cxl_endpoint_decoder *cxl_request_dpa(struct cxl_memdev *cxlmd,
 					     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);
+				     struct cxl_endpoint_decoder *cxled,
+				     bool avoid_dax);
 
 int cxl_accel_region_detach(struct cxl_endpoint_decoder *cxled);
 #endif