Prarit Bhargava: > On 02/07/2018 01:44 PM, Simon Gaiser wrote: >> Prarit Bhargava: >>> 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. >>> >>> 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 <[email protected]> >>> Cc: Thomas Gleixner <[email protected]> >>> Cc: Ingo Molnar <[email protected]> >>> Cc: "H. Peter Anvin" <[email protected]> >>> Cc: [email protected] >>> Cc: Peter Zijlstra <[email protected]> >>> Cc: Andi Kleen <[email protected]> >>> Cc: Dave Hansen <[email protected]> >>> Cc: Piotr Luc <[email protected]> >>> Cc: Kan Liang <[email protected]> >>> Cc: Borislav Petkov <[email protected]> >>> Cc: Stephane Eranian <[email protected]> >>> Cc: Prarit Bhargava <[email protected]> >>> Cc: Arvind Yadav <[email protected]> >>> Cc: Andy Lutomirski <[email protected]> >>> Cc: Christian Borntraeger <[email protected]> >>> Cc: "Kirill A. Shutemov" <[email protected]> >>> Cc: Tom Lendacky <[email protected]> >>> Cc: He Chen <[email protected]> >>> Cc: Mathias Krause <[email protected]> >>> Cc: Tim Chen <[email protected]> >>> Cc: Vitaly Kuznetsov <[email protected]> >>> --- >>> arch/x86/kernel/smpboot.c | 55 >>> +++++++++-------------------------------------- >>> 1 file changed, 10 insertions(+), 45 deletions(-) >>> >>> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c >>> index 838d36ff7ba6..2e3c5a394e79 100644 >>> --- a/arch/x86/kernel/smpboot.c >>> +++ b/arch/x86/kernel/smpboot.c >>> @@ -308,12 +308,6 @@ 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++; >>> if (new != pkg) >>> pr_info("CPU %u Converting physical %u to logical package %u\n", >>> @@ -323,44 +317,6 @@ 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); >>> - >>> - topology_update_package_map(c->phys_proc_id, cpu); >>> -} >>> - >>> void __init smp_store_boot_cpu_info(void) >>> { >>> int id = 0; /* CPU 0 */ >>> @@ -368,7 +324,7 @@ 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); >>> cpu_data(id).set = 1; >>> } >>> >>> @@ -1371,7 +1327,16 @@ 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); >> >> This breaks booting as Xen PV domain for me. The problem seems to be >> that native_smp_cpus_done() is never called on a PV domain. So >> __max_logical_packages is uninitialized and this leads to a NULL >> pointer dereference in coretemp. >> > > I'll see if I can figure out a way to test that.
Ok, thanks. If you need some logs, or if I should test something just
ask.
> Does 947134d9b00f
> ("x86/smpboot: Do not use smp_num_siblings in __max_logical_packages
> calculation") help?
No.
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