Re: [PATCH v6 1/9] cxl/hdm: Add helpers to restore and commit memdev decoders

[Dave Jiang]

On 5/28/26 4:06 AM, Richard Cheng wrote:
> On Thu, May 28, 2026 at 08:31:46AM +0800, Srirangan Madhavan wrote:

<-- snip -->

>> +static int cxl_restore_dvsec_range(struct cxl_memdev *cxlmd,
>> +				   struct cxl_endpoint_decoder *cxled)
>> +{
>> +	struct cxl_dev_state *cxlds = cxlmd->cxlds;
>> +	struct cxl_decoder *cxld = &cxled->cxld;
>> +	struct pci_dev *pdev = to_pci_dev(cxlds->dev);
>> +	u64 base = cxld->hpa_range.start;
>> +	u64 size = range_len(&cxld->hpa_range);
>> +	u32 lo;
>> +	int dvsec = cxlds->cxl_dvsec;
>> +	int id = cxld->id;
>> +	int rc;
>> +
>> +	if (!dvsec)
>> +		return 0;
>> +
>> +	if (id >= CXL_DVSEC_RANGE_MAX)
>> +		return 0;
>> +
>> +	rc = pci_write_config_dword(pdev, dvsec + PCI_DVSEC_CXL_RANGE_BASE_HIGH(id),
>> +				    upper_32_bits(base));
>> +	if (rc)
>> +		return rc;
>> +
>> +	rc = pci_read_config_dword(pdev, dvsec + PCI_DVSEC_CXL_RANGE_BASE_LOW(id),
>> +				   &lo);
>> +	if (rc)
>> +		return rc;
> 
> Here pci_read/write* returns positive values on failure, and you pass the value up.
> Eventually surfacing through cxl_reset_store to userspace where sysfs thinks positive
> values as "bytes written".
> 
> I think this might need a fix ?
Great catch! Not something I ever thought about before WRT pci_read/write*. I think to get errno it needs pcibios_err_to_errno() wrapper called. The sysfs exposure definitely needs to be audited.