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Subject[PATCH v2] x86/amd: Derive L3 shared_cpu_map from cpu_llc_shared_mask
Date
For system with X86_FEATURE_TOPOEXT, current logic use APIC ID to
calculate shared_cpu_map. However, since APIC IDs are not guaranteed
to be contiguous for cores across different L3 (e.g. family17h system
w/ downcore configuration). This breaks the logic, and results in
incorrect L3 shared_cpu_map.

Instead, always use the previously calculated cpu_llc_shared_mask of
each cpu to derive L3 shared_cpu_map. This has been tested on
family15h and family17h systems, which has L3 and support
X86_FEATURE_TOPOEXT.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
arch/x86/kernel/cpu/intel_cacheinfo.c | 32 ++++++++++++++++++--------------
1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/arch/x86/kernel/cpu/intel_cacheinfo.c b/arch/x86/kernel/cpu/intel_cacheinfo.c
index c55fb2c..24f74932 100644
--- 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(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;
@@ -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;

--
2.7.4
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