Messages in this thread Patch in this message | | | From | Prarit Bhargava <> | Subject | [PATCH v5 3/3] x86/smpboot: Fix __max_logical_packages estimate | Date | Sun, 5 Nov 2017 11:54:28 -0500 |
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A system booted with a small number of cores enabled per package panics because the estimate of __max_logical_packages is too low. This occurs when the total number of active cores across all packages is less than the maximum core count for a single package.
ie) On a 4 package system with 20 cores/package where only 4 cores are enabled on each package, the value of __max_logical_packages is calculated as DIV_ROUND_UP(16 / 20) = 1 and not 4.
Here's an example of the panic:
smpboot: Booting Node 1, Processors #1 OK smpboot: Package 1 of CPU 1 exceeds BIOS package data 1. ------------[ cut here ]------------ kernel BUG at arch/x86/kernel/cpu/common.c:1087! invalid opcode: 0000 [#1] SMP Modules linked in: CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.14.0-rc2+ #4
Calculate __max_logical_packages after the cpu enumeration has completed. Use the boot cpu's data to extrapolate the number of packages.
Signed-off-by: Prarit Bhargava <prarit@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: x86@kernel.org Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Piotr Luc <piotr.luc@intel.com> Cc: Kan Liang <kan.liang@intel.com> Cc: Borislav Petkov <bp@suse.de> Cc: Stephane Eranian <eranian@google.com> Cc: Arvind Yadav <arvind.yadav.cs@gmail.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: He Chen <he.chen@linux.intel.com> Cc: Mathias Krause <minipli@googlemail.com> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> --- arch/x86/kernel/smpboot.c | 57 +++++++++-------------------------------------- 1 file changed, 10 insertions(+), 47 deletions(-)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 580261f8a2bf..c122720dfb34 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -317,12 +317,6 @@ int topology_update_package_map(unsigned int pkg, unsigned int cpu) if (new >= 0) goto found; - if (logical_packages >= __max_logical_packages) { - pr_warn("Package %u of CPU %u exceeds BIOS package data %u.\n", - logical_packages, cpu, __max_logical_packages); - return -ENOSPC; - } - new = logical_packages++; /* Allocate and copy a new array */ @@ -346,46 +340,6 @@ int topology_update_package_map(unsigned int pkg, unsigned int cpu) return 0; } -static void __init smp_init_package_map(struct cpuinfo_x86 *c, unsigned int cpu) -{ - unsigned int ncpus; - - /* - * Today neither Intel nor AMD support heterogenous systems. That - * might change in the future.... - * - * While ideally we'd want '* smp_num_siblings' in the below @ncpus - * computation, this won't actually work since some Intel BIOSes - * report inconsistent HT data when they disable HT. - * - * In particular, they reduce the APIC-IDs to only include the cores, - * but leave the CPUID topology to say there are (2) siblings. - * This means we don't know how many threads there will be until - * after the APIC enumeration. - * - * By not including this we'll sometimes over-estimate the number of - * logical packages by the amount of !present siblings, but this is - * still better than MAX_LOCAL_APIC. - * - * We use total_cpus not nr_cpu_ids because nr_cpu_ids can be limited - * on the command line leading to a similar issue as the HT disable - * problem because the hyperthreads are usually enumerated after the - * primary cores. - */ - ncpus = boot_cpu_data.x86_max_cores; - if (!ncpus) { - pr_warn("x86_max_cores == zero !?!?"); - ncpus = 1; - } - - __max_logical_packages = DIV_ROUND_UP(total_cpus, ncpus); - pr_info("Max logical packages: %u\n", __max_logical_packages); - - logical_packages = 0; - - topology_update_package_map(c->phys_proc_id, cpu); -} - void __init smp_store_boot_cpu_info(void) { int id = 0; /* CPU 0 */ @@ -393,7 +347,7 @@ void __init smp_store_boot_cpu_info(void) *c = boot_cpu_data; c->cpu_index = id; - smp_init_package_map(c, id); + topology_update_package_map(c->phys_proc_id, id); } /* @@ -1393,7 +1347,16 @@ void __init native_smp_prepare_boot_cpu(void) void __init native_smp_cpus_done(unsigned int max_cpus) { + int ncpus; + pr_debug("Boot done\n"); + /* + * Today neither Intel nor AMD support heterogenous systems so + * extrapolate the boot cpu's data to all packages. + */ + ncpus = cpu_data(0).booted_cores * smp_num_siblings; + __max_logical_packages = DIV_ROUND_UP(nr_cpu_ids, ncpus); + pr_info("Max logical packages: %u\n", __max_logical_packages); if (x86_has_numa_in_package) set_sched_topology(x86_numa_in_package_topology); -- 2.15.0.rc0.39.g2f0e14e64
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