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Commit 2b83809a authored by Suravee Suthikulpanit's avatar Suravee Suthikulpanit Committed by Ingo Molnar
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x86/cpu/amd: Derive L3 shared_cpu_map from cpu_llc_shared_mask 



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: default avatarSuravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: default avatarBorislav 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: default avatarIngo Molnar <mingo@kernel.org>
parent b89b41d0

arch/x86/kernel/cpu/intel_cacheinfo.c

+18 −14
Original line number Diff line number Diff line
@@ -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;