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x86/cpu/amd: Derive L3 shared_cpu_map from cpu_llc_shared_mask
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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 <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
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ssuthiku-amd authored and Ingo Molnar committed Aug 10, 2017
1 parent b89b41d commit 2b83809
Showing 1 changed file with 18 additions and 14 deletions.
32 changes: 18 additions & 14 deletions arch/x86/kernel/cpu/intel_cacheinfo.c
Original file line number Diff line number Diff line change
Expand Up @@ -811,7 +811,24 @@ static int __cache_amd_cpumap_setup(unsigned int cpu, int index,
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;
Expand Down Expand Up @@ -839,19 +856,6 @@ static int __cache_amd_cpumap_setup(unsigned int cpu, int index,
&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
return 0;

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