Re: [PATCH v29 4/5] sfc: obtain and map cxl range using devm_cxl_probe_mem

["Dan Williams (nvidia)" <djbw@kernel.org>]

sashiko-bot@ wrote:
> Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
> - [High] Resource Teardown Ordering Violation in efx_pci_remove
> - [High] Missing Hardware State Restoration for CXL HDM Decoders After FLR
> --
> 
> commit cd561fb9993e195accb646b7a8524a13a2dd0b79
> Author: Alejandro Lucero <alucerop@amd.com>
> Subject: sfc: obtain and map cxl range using devm_cxl_probe_mem
> 
> This commit introduces CXL support to the sfc driver by creating a CXL
> memory device using devm_cxl_probe_mem() and mapping the CXL range for
> CTPIO buffer usage.
> 
> > diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
> > --- 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);
> 
> [Severity: High]
> Does this tear down resources in the correct order?
> 
> efx_fini_io() calls pci_disable_device() which disables memory decoding for
> the endpoint.
> 
> Because the CXL memdev and its sysfs interfaces are managed by devres
> (created via devm_cxl_probe_mem() during probe), they remain active until
> devres_release_all() runs after efx_pci_remove() returns.
> 
> If userspace (e.g., CXL utilities, udev) accesses the CXL sysfs attributes
> in this window, the CXL core will attempt to read memory-mapped component
> registers on the disabled device.
> 
> Could this result in PCIe Unsupported Requests (UR) and a fatal AER fault or
> kernel panic?
> 
> >  
> >  	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
> > --- a/drivers/net/ethernet/sfc/efx_cxl.c
> > +++ b/drivers/net/ethernet/sfc/efx_cxl.c
> 
> [ ... ]
> 
> > @@ -73,9 +74,31 @@ int efx_cxl_init(struct efx_probe_data *probe_data)
> >  		return -ENODEV;
> >  	}
> >  
> > +	cxl->cxlmd = devm_cxl_probe_mem(&cxl->cxlds, &cxl_pio_range);
> 
> [Severity: High]
> Is there a mechanism to restore the CXL HDM decoders after a Function Level
> Reset (FLR)?

FLR does not impact CXL settings.