Make num_cache_leaves a per-CPU variable. Otherwise, populate_cache_ leaves() fails on systems with asymmetric number of subleaves in CPUID leaf 0x4. Intel Meteor Lake is an example of such a system.

Cc: Srinivas Pandruvada srinivas.pandruvada@linux.intel.com Cc: Len Brown len.brown@intel.com Cc: "Rafael J. Wysocki" rafael.j.wysocki@intel.com Cc: Zhang Rui rui.zhang@intel.com Cc: Chen Yu yu.c.chen@intel.com Cc: stable@vger.kernel.org Reviewed-by: Len Brown len.brown@intel.com Signed-off-by: Ricardo Neri ricardo.neri-calderon@linux.intel.com --- After this change, all CPUs will traverse CPUID leaf 0x4 when booted for the first time. On systems with asymmetric cache topologies this is useless work.

Creating a list of processor models that have asymmetric cache topologies was considered. The burden of maintaining such list would outweigh the performance benefit of skipping this extra step. --- arch/x86/kernel/cpu/cacheinfo.c | 48 ++++++++++++++++++++------------- 1 file changed, 29 insertions(+), 19 deletions(-)

diff --git a/arch/x86/kernel/cpu/cacheinfo.c b/arch/x86/kernel/cpu/cacheinfo.c index 4063e8991211..6ad51657c853 100644 --- a/arch/x86/kernel/cpu/cacheinfo.c +++ b/arch/x86/kernel/cpu/cacheinfo.c @@ -176,7 +176,18 @@ struct _cpuid4_info_regs { struct amd_northbridge *nb; };

-static unsigned short num_cache_leaves; +static DEFINE_PER_CPU(unsigned short, num_cache_leaves); + +static inline unsigned short get_num_cache_leaves(unsigned int cpu) +{ + return per_cpu(num_cache_leaves, cpu); +} + +static inline void +set_num_cache_leaves(unsigned short nr_leaves, unsigned int cpu) +{ + per_cpu(num_cache_leaves, cpu) = nr_leaves; +}

/* AMD doesn't have CPUID4. Emulate it here to report the same information to the user. This makes some assumptions about the machine: @@ -716,19 +727,21 @@ void cacheinfo_hygon_init_llc_id(struct cpuinfo_x86 *c, int cpu) void init_amd_cacheinfo(struct cpuinfo_x86 *c) {

+ unsigned int cpu = c->cpu_index; + if (boot_cpu_has(X86_FEATURE_TOPOEXT)) { - num_cache_leaves = find_num_cache_leaves(c); + set_num_cache_leaves(find_num_cache_leaves(c), cpu); } else if (c->extended_cpuid_level >= 0x80000006) { if (cpuid_edx(0x80000006) & 0xf000) - num_cache_leaves = 4; + set_num_cache_leaves(4, cpu); else - num_cache_leaves = 3; + set_num_cache_leaves(3, cpu); } }

void init_hygon_cacheinfo(struct cpuinfo_x86 *c) { - num_cache_leaves = find_num_cache_leaves(c); + set_num_cache_leaves(find_num_cache_leaves(c), c->cpu_index); }

void init_intel_cacheinfo(struct cpuinfo_x86 *c) @@ -738,24 +751,21 @@ void init_intel_cacheinfo(struct cpuinfo_x86 *c) unsigned int new_l1d = 0, new_l1i = 0; /* Cache sizes from cpuid(4) */ unsigned int new_l2 = 0, new_l3 = 0, i; /* Cache sizes from cpuid(4) */ unsigned int l2_id = 0, l3_id = 0, num_threads_sharing, index_msb; -#ifdef CONFIG_SMP unsigned int cpu = c->cpu_index; -#endif

if (c->cpuid_level > 3) { - static int is_initialized; - - if (is_initialized == 0) { - /* Init num_cache_leaves from boot CPU */ - num_cache_leaves = find_num_cache_leaves(c); - is_initialized++; - } + /* + * There should be at least one leaf. A non-zero value means + * that the number of leaves has been initialized. + */ + if (!get_num_cache_leaves(cpu)) + set_num_cache_leaves(find_num_cache_leaves(c), cpu);

/* * Whenever possible use cpuid(4), deterministic cache * parameters cpuid leaf to find the cache details */ - for (i = 0; i < num_cache_leaves; i++) { + for (i = 0; i < get_num_cache_leaves(cpu); i++) { struct _cpuid4_info_regs this_leaf = {}; int retval;

@@ -791,14 +801,14 @@ void init_intel_cacheinfo(struct cpuinfo_x86 *c) * Don't use cpuid2 if cpuid4 is supported. For P4, we use cpuid2 for * trace cache */ - if ((num_cache_leaves == 0 || c->x86 == 15) && c->cpuid_level > 1) { + if ((!get_num_cache_leaves(cpu) || c->x86 == 15) && c->cpuid_level > 1) { /* supports eax=2 call */ int j, n; unsigned int regs[4]; unsigned char *dp = (unsigned char *)regs; int only_trace = 0;

- if (num_cache_leaves != 0 && c->x86 == 15) + if (get_num_cache_leaves(cpu) && c->x86 == 15) only_trace = 1;

/* Number of times to iterate */ @@ -1000,12 +1010,12 @@ int init_cache_level(unsigned int cpu) { struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);

- if (!num_cache_leaves) + if (!get_num_cache_leaves(cpu)) return -ENOENT; if (!this_cpu_ci) return -EINVAL; this_cpu_ci->num_levels = 3; - this_cpu_ci->num_leaves = num_cache_leaves; + this_cpu_ci->num_leaves = get_num_cache_leaves(cpu); return 0; }