On AMD processors that support extended CPUID leaf 0x80000026, use the
extended leaf to parse the topology information. In case of a failure,
fall back to parsing the information from CPUID leaf 0xb.
CPUID leaf 0x80000026 exposes the "CCX" and "CCD (Die)" information on
AMD processors which have been mapped to TOPO_TILE_DOMAIN and
TOPO_DIE_DOMAIN respectively.
Since this information was previously not available via CPUID leaf 0xb
or 0x8000001e, the "die_id", "logical_die_id", "max_die_per_pkg",
"die_cpus", and "die_cpus_list" will differ with this addition on
AMD processors that support extended CPUID leaf 0x80000026 and contain
more than one "CCD (Die)" on the package.
For example, following are the changes in the values reported by
"/sys/kernel/debug/x86/topo/cpus/16" after applying this patch on a 4th
Generation AMD EPYC System (1 x 128C/256T):
(CPU16 is the first CPU of the second CCD on the package)
tip:x86/apic tip:x86/apic
+ this patch
online: 1 1
initial_apicid: 80 80
apicid: 80 80
pkg_id: 0 0
die_id: 0 4 *
cu_id: 255 255
core_id: 64 64
logical_pkg_id: 0 0
logical_die_id: 0 4 *
llc_id: 8 8
l2c_id: 65535 65535
amd_node_id: 0 0
amd_nodes_per_pkg: 1 1
num_threads: 256 256
num_cores: 128 128
max_dies_per_pkg: 1 8 *
max_threads_per_core:2 2
[ prateek: commit log, updated comment in topoext_amd.c, changed has_0xb
to has_topoext, rebased the changes on tip:x86/apic, tested the
changes on 4th Gen AMD EPYC system ]
[ mingo: tidy up the changelog a bit more ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20240314050432.1710-1-kprateek.nayak@amd.com
detect_extended_topology() along with it's early() variant is a classic
example for duct tape engineering:
- It evaluates an array of subleafs with a boatload of local variables
for the relevant topology levels instead of using an array to save the
enumerated information and propagate it to the right level
- It has no boundary checks for subleafs
- It prevents updating the die_id with a crude workaround instead of
checking for leaf 0xb which does not provide die information.
- It's broken vs. the number of dies evaluation as it uses:
num_processors[DIE_LEVEL] / num_processors[CORE_LEVEL]
which "works" only correctly if there is none of the intermediate
topology levels (MODULE/TILE) enumerated.
There is zero value in trying to "fix" that code as the only proper fix is
to rewrite it from scratch.
Implement a sane parser with proper code documentation, which will be used
for the consolidated topology evaluation in the next step.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Tested-by: Wang Wendy <wendy.wang@intel.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20240212153624.830571770@linutronix.de
