Re: [PATCH v27 4/5] sfc: obtain and map cxl range using devm_cxl_probe_mem

[Alejandro Lucero Palau <alucerop@amd.com>]

On 6/9/26 22:58, Dave Jiang wrote:
>
> On 6/9/26 2:57 PM, alejandro.lucero-palau@amd.com wrote:
>> From: Alejandro Lucero <alucerop@amd.com>
>>
>> Use core API for safely obtain the CXL range linked to an HDM committed
>> by the BIOS. Map such a range for being used as the ctpio buffer.
>>
>> A potential user space action through sysfs unbinding or core cxl
>> modules remove will trigger sfc driver device detachment, with that case
>> not racing with this mapping as this is done during driver probe and
>> therefore protected with device lock against those user space actions.
>>
>> Signed-off-by: Alejandro Lucero <alucerop@amd.com>
>> ---
>>   drivers/net/ethernet/sfc/efx.c     |  1 +
>>   drivers/net/ethernet/sfc/efx_cxl.c | 24 ++++++++++++++++++++++++
>>   drivers/net/ethernet/sfc/efx_cxl.h |  3 +++
>>   3 files changed, 28 insertions(+)
>>
>> diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
>> index 90ccbe310386..578054c21e79 100644
>> --- a/drivers/net/ethernet/sfc/efx.c
>> +++ b/drivers/net/ethernet/sfc/efx.c
>> @@ -984,6 +984,7 @@ static void efx_pci_remove(struct pci_dev *pci_dev)
>>   	efx_fini_io(efx);
>>   
>>   	probe_data = container_of(efx, struct efx_probe_data, efx);
>> +	efx_cxl_exit(probe_data);
>>   
>>   	pci_dbg(efx->pci_dev, "shutdown successful\n");
>>   
>> diff --git a/drivers/net/ethernet/sfc/efx_cxl.c b/drivers/net/ethernet/sfc/efx_cxl.c
>> index 4d55c08cf2a1..d5766a40e2cf 100644
>> --- a/drivers/net/ethernet/sfc/efx_cxl.c
>> +++ b/drivers/net/ethernet/sfc/efx_cxl.c
>> @@ -18,6 +18,7 @@ int efx_cxl_init(struct efx_probe_data *probe_data)
>>   {
>>   	struct efx_nic *efx = &probe_data->efx;
>>   	struct pci_dev *pci_dev = efx->pci_dev;
>> +	struct range cxl_pio_range;
>>   	struct efx_cxl *cxl;
>>   	u16 dvsec;
>>   	int rc;
>> @@ -75,9 +76,32 @@ int efx_cxl_init(struct efx_probe_data *probe_data)
>>   		return -ENODEV;
>>   	}
>>   
>> +	cxl->cxlmd = devm_cxl_probe_mem(&cxl->cxlds, &cxl_pio_range);
>> +	if (IS_ERR(cxl->cxlmd)) {
>> +		pci_err(pci_dev, "CXL accel memdev creation failed\n");
>> +		return PTR_ERR(cxl->cxlmd);
>> +	}
>> +
>> +	cxl->ctpio_cxl = ioremap_wc(cxl_pio_range.start,
>> +				    range_len(&cxl_pio_range));
> Should this be devm managed? I think the mapping leaks if efx_pci_probe() fails after calling efx_cxl_init().
>   


No devm under netdev ... but you are right about the leak. I need to add 
a call to efx_cxl_exit inside the error path in the caller.


>> +	if (!cxl->ctpio_cxl) {
>> +		pci_err(pci_dev, "CXL ioremap region (%pra) failed\n",
>> +			&cxl_pio_range);
>> +		return -ENOMEM;
>> +	}
>> +
>> +	probe_data->cxl_pio_initialised = true;
> Should this change be moved to the follow on patch that uses it?


I can do that.


Thanks!


> DJ
>>   	probe_data->cxl = cxl;
>>   
>>   	return 0;
>>   }
>>   
>> +void efx_cxl_exit(struct efx_probe_data *probe_data)
>> +{
>> +	if (!probe_data->cxl)
>> +		return;
>> +
>> +	iounmap(probe_data->cxl->ctpio_cxl);
>> +}
>> +
>>   MODULE_IMPORT_NS("CXL");
>> diff --git a/drivers/net/ethernet/sfc/efx_cxl.h b/drivers/net/ethernet/sfc/efx_cxl.h
>> index 04e46278464d..3e2705cb063f 100644
>> --- a/drivers/net/ethernet/sfc/efx_cxl.h
>> +++ b/drivers/net/ethernet/sfc/efx_cxl.h
>> @@ -20,10 +20,13 @@ struct efx_probe_data;
>>   struct efx_cxl {
>>   	struct cxl_dev_state cxlds;
>>   	struct cxl_memdev *cxlmd;
>> +	void __iomem *ctpio_cxl;
>>   };
>>   
>>   int efx_cxl_init(struct efx_probe_data *probe_data);
>> +void efx_cxl_exit(struct efx_probe_data *probe_data);
>>   #else
>>   static inline int efx_cxl_init(struct efx_probe_data *probe_data) { return 0; }
>> +static inline void efx_cxl_exit(struct efx_probe_data *probe_data) {}
>>   #endif
>>   #endif