linux-kernel - RE: [PATCH v2 0/7] x86/resctrl : Support L3 Smart Data Cache Injection Allocation Enforcement (SDCIAE)

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Message-ID: <SJ1PR11MB60837B532254E7B23BC27E84FC052@SJ1PR11MB6083.namprd11.prod.outlook.com>
Date: Wed, 18 Dec 2024 23:27:11 +0000
From: "Luck, Tony" <tony.luck@...el.com>
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Subject: RE: [PATCH v2 0/7] x86/resctrl : Support L3 Smart Data Cache
 Injection Allocation Enforcement (SDCIAE)

I don't have an AMD system, so I added a couple of hacks to the code to pretend I did.
My hacks might have missed something, so the below test may not fail for you.

My test:

# echo 1 > info/L3/io_alloc
# cat info/L3/bit_usage

This gave me a console splat starting with:

[  163.801078] invalid mode for closid 14

That happened because in rdt_bit_usage_show()

                for (i = 0; i < closids_supported(); i++) {
                        if (!closid_allocated(i))
                                continue;
                        ctrl_val = resctrl_arch_get_config(r, dom, i,
                                                           s->conf_type);
                        mode = rdtgroup_mode_by_closid(i);

CLOSID 14 is my highest. It's supported, and allocated.

rdtgroup_mode_by_closid() searches rdt_all_groups to find
one using CLOSID 14, but there isn't one. So it returns
RDT_NUM_MODES

Maybe RDT_NUM_MODES isn't invalid in the switch()
Looks like it should be same action as RDT_MODE_SHAREABLE?

-Tony