Re: [RFC Patch v1 1/3] cxl/core: Fix caching dport GPF DVSEC issue

[Jonathan Cameron]

On Fri, 21 Mar 2025 00:41:54 -0700
Davidlohr Bueso <dave@xxxxxxxxxxxx> wrote:

> On Wed, 19 Mar 2025, Li Ming wrote:
> 
> >Per Table 8-2 in CXL r3.2 section 8.1.1 and CXL r3.2 section 8.1.6, only
> >CXL Downstream switch ports and CXL root ports have GPF DVSEC for CXL
> >Port(DVSEC ID 04h).
> >
> >CXL subsystem has a gpf_dvsec in struct cxl_port which is used to cache
> >the offset of a GPF DVSEC in PCIe configuration space. It will be
> >updated during the first EP attaching to the cxl_port, so the gpf_dvsec
> >can only cache the GPF DVSEC offset of the dport which the first EP is
> >under. Will not have chance to update it during other EPs attaching.
> >That means CXL subsystem will use the same GPF DVSEC offset for all
> >dports under the port, it will be a problem if the GPF DVSEC offset
> >cached in cxl_port is not the right offset for a dport.
> >
> >Moving gpf_dvsec from struct cxl_port to struct cxl_dport, make every
> >cxl dport has their own GPF DVSEC offset caching, and each cxl dport
> >uses its own GPF DVSEC offset for GPF DVSEC accessing.  
> 
> This conversion looks good if necessary.
> 
> Reviewed-by: Davidlohr Bueso <dave@xxxxxxxxxxxx>

Whilst I somewhat doubt we'll see this in the wild, they could indeed
be different.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>