4.13-stable review patch. If anyone has any objections, please let me know. ------------------ From: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx> 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@xxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/20170731085159.9455-3-bp@xxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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