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Subject[PATCH 4.13 34/35] x86/cpu/amd: Derive L3 shared_cpu_map from cpu_llc_shared_mask
Date
4.13-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>

commit 2b83809a5e6d619a780876fcaf68cdc42b50d28c upstream.

For systems with X86_FEATURE_TOPOEXT, current logic uses the APIC ID
to calculate shared_cpu_map. However, APIC IDs are not guaranteed to
be contiguous for cores across different L3s (e.g. family17h system
w/ downcore configuration). This breaks the logic, and results in an
incorrect L3 shared_cpu_map.

Instead, always use the previously calculated cpu_llc_shared_mask of
each CPU to derive the L3 shared_cpu_map.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170731085159.9455-3-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/kernel/cpu/intel_cacheinfo.c | 32 ++++++++++++++++++--------------
1 file changed, 18 insertions(+), 14 deletions(-)

--- a/arch/x86/kernel/cpu/intel_cacheinfo.c
+++ b/arch/x86/kernel/cpu/intel_cacheinfo.c
@@ -811,7 +811,24 @@ static int __cache_amd_cpumap_setup(unsi
struct cacheinfo *this_leaf;
int i, sibling;

- if (boot_cpu_has(X86_FEATURE_TOPOEXT)) {
+ /*
+ * For L3, always use the pre-calculated cpu_llc_shared_mask
+ * to derive shared_cpu_map.
+ */
+ if (index == 3) {
+ for_each_cpu(i, cpu_llc_shared_mask(cpu)) {
+ this_cpu_ci = get_cpu_cacheinfo(i);
+ if (!this_cpu_ci->info_list)
+ continue;
+ this_leaf = this_cpu_ci->info_list + index;
+ for_each_cpu(sibling, cpu_llc_shared_mask(cpu)) {
+ if (!cpu_online(sibling))
+ continue;
+ cpumask_set_cpu(sibling,
+ &this_leaf->shared_cpu_map);
+ }
+ }
+ } else if (boot_cpu_has(X86_FEATURE_TOPOEXT)) {
unsigned int apicid, nshared, first, last;

this_leaf = this_cpu_ci->info_list + index;
@@ -837,19 +854,6 @@ static int __cache_amd_cpumap_setup(unsi
continue;
cpumask_set_cpu(sibling,
&this_leaf->shared_cpu_map);
- }
- }
- } else if (index == 3) {
- for_each_cpu(i, cpu_llc_shared_mask(cpu)) {
- this_cpu_ci = get_cpu_cacheinfo(i);
- if (!this_cpu_ci->info_list)
- continue;
- this_leaf = this_cpu_ci->info_list + index;
- for_each_cpu(sibling, cpu_llc_shared_mask(cpu)) {
- if (!cpu_online(sibling))
- continue;
- cpumask_set_cpu(sibling,
- &this_leaf->shared_cpu_map);
}
}
} else

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