netdev - Re: [PATCH v2 11/15] cxl: make region type based on endpoint type

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Message-ID: <1cd50929-35f5-d0f1-9a68-d22e28cdf1b6@amd.com>
Date: Tue, 16 Jul 2024 09:13:18 +0100
From: Alejandro Lucero Palau <alucerop@....com>
To: "Li, Ming4" <ming4.li@...el.com>, alejandro.lucero-palau@....com,
 linux-cxl@...r.kernel.org, netdev@...r.kernel.org, dan.j.williams@...el.com,
 martin.habets@...inx.com, edward.cree@....com, davem@...emloft.net,
 kuba@...nel.org, pabeni@...hat.com, edumazet@...gle.com,
 richard.hughes@....com
Subject: Re: [PATCH v2 11/15] cxl: make region type based on endpoint type


On 7/16/24 08:14, Li, Ming4 wrote:
> On 7/16/2024 1:28 AM, alejandro.lucero-palau@....com wrote:
>> From: Alejandro Lucero <alucerop@....com>
>>
>> Current code is expecting Type3 or CXL_DECODER_HOSTONLYMEM devices only.
>> Suport for Type2 implies region type needs to be based on the endpoint
>> type instead.
>>
>> Signed-off-by: Alejandro Lucero <alucerop@....com>
>> ---
>>   drivers/cxl/core/region.c | 14 +++++++++-----
>>   1 file changed, 9 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
>> index ca464bfef77b..5cc71b8868bc 100644
>> --- a/drivers/cxl/core/region.c
>> +++ b/drivers/cxl/core/region.c
>> @@ -2645,7 +2645,8 @@ static ssize_t create_ram_region_show(struct device *dev,
>>   }
>>   
>>   static struct cxl_region *__create_region(struct cxl_root_decoder *cxlrd,
>> -					  enum cxl_decoder_mode mode, int id)
>> +					  enum cxl_decoder_mode mode, int id,
>> +					  enum cxl_decoder_type target_type)
>>   {
>>   	int rc;
>>   
>> @@ -2667,7 +2668,7 @@ static struct cxl_region *__create_region(struct cxl_root_decoder *cxlrd,
>>   		return ERR_PTR(-EBUSY);
>>   	}
>>   
>> -	return devm_cxl_add_region(cxlrd, id, mode, CXL_DECODER_HOSTONLYMEM);
>> +	return devm_cxl_add_region(cxlrd, id, mode, target_type);
>>   }
>>   
>>   static ssize_t create_pmem_region_store(struct device *dev,
>> @@ -2682,7 +2683,8 @@ static ssize_t create_pmem_region_store(struct device *dev,
>>   	if (rc != 1)
>>   		return -EINVAL;
>>   
>> -	cxlr = __create_region(cxlrd, CXL_DECODER_PMEM, id);
>> +	cxlr = __create_region(cxlrd, CXL_DECODER_PMEM, id,
>> +			       CXL_DECODER_HOSTONLYMEM);
>>   	if (IS_ERR(cxlr))
>>   		return PTR_ERR(cxlr);
>>   
>> @@ -2702,7 +2704,8 @@ static ssize_t create_ram_region_store(struct device *dev,
>>   	if (rc != 1)
>>   		return -EINVAL;
>>   
>> -	cxlr = __create_region(cxlrd, CXL_DECODER_RAM, id);
>> +	cxlr = __create_region(cxlrd, CXL_DECODER_RAM, id,
>> +			       CXL_DECODER_HOSTONLYMEM);
>>   	if (IS_ERR(cxlr))
>>   		return PTR_ERR(cxlr);
>>   
>> @@ -3364,7 +3367,8 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
>>   
>>   	do {
>>   		cxlr = __create_region(cxlrd, cxled->mode,
>> -				       atomic_read(&cxlrd->region_id));
>> +				       atomic_read(&cxlrd->region_id),
>> +				       cxled->cxld.target_type);
>>   	} while (IS_ERR(cxlr) && PTR_ERR(cxlr) == -EBUSY);
>>   
>>   	if (IS_ERR(cxlr)) {
> I think that one more check between the type of root decoder and endpoint decoder is necessary in this case. Currently, root decoder type is hard coded to CXL_DECODER_HOSTONLYMEM, but it should be CXL_DECODER_DEVMEM or CXL_DECODER_HOSTONLYMEM based on cfmws->restrictions.
>

I think you are completely right.

I will work on this looking also for other implications.

Thanks


>