RE: [PATCH] EDAC/{i10nm,skx,skx_common}: Support multiple clumps

[Zhuo, Qiuxu]

> From: Kyle Meyer <kyle.meyer@xxxxxxx>
> Sent: Friday, December 6, 2024 8:57 AM
> To: Luck, Tony <tony.luck@xxxxxxxxx>
> Cc: bp@xxxxxxxxx; james.morse@xxxxxxx; mchehab@xxxxxxxxxx;
> rric@xxxxxxxxxx; linux-edac@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH] EDAC/{i10nm,skx,skx_common}: Support multiple
> clumps
> 
> On Thu, Dec 05, 2024 at 03:57:55PM -0800, Luck, Tony wrote:
> > > +int skx_get_src_id(struct skx_dev *d, int off, u8 *id) { #ifdef
> > > +CONFIG_NUMA
> > > +	return skx_get_pkg_id(d, id);
> > > +#else
> > > +	u32 reg;
> > > +
> > > +	if (pci_read_config_dword(d->util_all, off, &reg)) {
> > > +		skx_printk(KERN_ERR, "Failed to read src id\n");
> > > +		return -ENODEV;
> > > +	}
> > > +
> > > +	*id = GET_BITFIELD(reg, 12, 14);
> > > +	return 0;
> > > +#endif
> >
> > Doh ... I alwasy forget about IS_ENABLED(). This can be written:
> >
> >
> > int skx_get_src_id(struct skx_dev *d, int off, u8 *id) {
> > 	u32 reg;
> >
> > 	if (IS_ENABLED(CONFIG_NUMA))
> > 		return skx_get_pkg_id(d, id);
> >
> > 	if (pci_read_config_dword(d->util_all, off, &reg)) {
> > 		skx_printk(KERN_ERR, "Failed to read src id\n");
> > 		return -ENODEV;
> > 	}
> >
> > 	*id = GET_BITFIELD(reg, 12, 14);
> > 	return 0;
> > }
> 
> Looks good.
> 
> > 1) Does this work? I tried on a non-clumpy system that is NUMA.
> 
> Yes, I just tested this on a Sapphire Rapids system with multiple UPI domains.
> 
> > 2) Is it better (assuming #fidef factored off into a .h file)?
> 
> IMO, yes, but there's one subtle difference. EDAC will not load on systems that
> have a single UPI domain when CONFIG_NUMA is enabled but numa=off,
> because
> pcibus_to_node() in skx_get_pkg_id() will return NUMA_NO_NODE (-1). Is
> that a case that we need to worry about?

I think we need to make the EDAC load/work even in this case. 
Regardless of CONFIG_NUMA or whether numa=off is set or not, could we do it like this:

int skx_get_src_id(struct skx_dev *d, int off, u8 *id)
{
        u32 reg;

        if (!skx_get_pkg_id(d, id))
                return 0;

        if (pci_read_config_dword(d->util_all, off, &reg)) {
                skx_printk(KERN_ERR, "Failed to read src id\n");
                return -ENODEV;
        }

        *id = GET_BITFIELD(reg, 12, 14);
        return 0;
}

-Qiuxu