Re: [PATCH 1/3] cxl: Add check for result of interleave ways plus granularity combo

[Dave Jiang <dave.jiang@intel.com>]

On 8/9/2022 10:06 AM, Alison Schofield wrote:
> Dave - Haven't reviewed yet, but wanted to drop this tidbit -
>
> On Mon, Aug 08, 2022 at 02:06:57PM -0700, Dave Jiang wrote:
>> Add a helper function to check the combination of interleave ways and
>> interleave granularity together is sane against the interleave mask from
>> the HDM decoder. Add the check to cxl_region_attach() to make sure the
>> region config is sane. Add the check to cxl_port_setup_targets() to make
>> sure the port setup config is also sane.
>>
>> Calculation refers to CXL spec v3 8.2.4.19.13 implementation note #3.
>>
>> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> snip
>
>> +static inline int cxl_interleave_verify(struct cxl_port *port,
>> +					int ways, int granularity)
>> +{
>> +	struct cxl_hdm *cxlhdm = dev_get_drvdata(&port->dev);
>> +	unsigned int addr_mask;
>> +	u16 ig;
>> +	u8 iw;
> s/ig/eig
> s/iw/eiw
> For consistency, let's use the "e" version of these names to mean
> encoded value.

Ok. Good suggestion.


>    
>
>> +	int rc;
>> +
>> +	rc = granularity_to_cxl(granularity, &ig);
>> +	if (rc)
>> +		return rc;
>> +
>> +	rc = ways_to_cxl(ways, &iw);
>> +	if (rc)
>> +		return rc;
>> +
>> +	if (iw == 0)
>> +		return 0;
>> +
>> +	if (iw < CXL_INTERLEAVE_3_WAY)
>> +		addr_mask = GENMASK(ig + 8 + iw - 1, ig + 8);
>> +	else
>> +		addr_mask = GENMASK((ig + iw) / 3 - 1, ig + 8);
>> +
>> +	if (~cxlhdm->interleave_mask & addr_mask)
>> +		return -EINVAL;
>> +
>> +	return 0;
>> +}
>> +
>>   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);
>>
>>