From 12d3b559b85e75640b79995e1320588d6f0d5630 Mon Sep 17 00:00:00 2001 From: Huacai Chen Date: Sat, 20 Jul 2024 22:40:58 +0800 Subject: [PATCH] LoongArch: Always enumerate MADT and setup logical-physical CPU mapping Some drivers want to use cpu_logical_map(), early_cpu_to_node() and some other CPU mapping APIs, even if we use "nr_cpus=1" to hard limit the CPU number. This is strongly required for the multi-bridges machines. Currently, we stop parsing the MADT if the nr_cpus limit is reached, but to achieve the above goal we should always enumerate the MADT table and setup logical-physical CPU mapping whether there is a nr_cpus limit. Rework the MADT enumeration: 1. Define a flag "cpu_enumerated" to distinguish the first enumeration (cpu_enumerated=0) and the physical hotplug case (cpu_enumerated=1) for set_processor_mask(). 2. If cpu_enumerated=0, stop parsing only when NR_CPUS limit is reached, so we can setup logical-physical CPU mapping; if cpu_enumerated=1, stop parsing when nr_cpu_ids limit is reached, so we can avoid some runtime bugs. Once logical-physical CPU mapping is setup, we will let cpu_enumerated=1. 3. Use find_first_zero_bit() instead of cpumask_next_zero() to find the next zero bit (free logical CPU id) in the cpu_present_mask, because cpumask_next_zero() will stop at nr_cpu_ids. 4. Only touch cpu_possible_mask if cpu_enumerated=0, this is in order to avoid some potential crashes, because cpu_possible_mask is marked as __ro_after_init. 5. In prefill_possible_map(), clear cpu_present_mask bits greater than nr_cpu_ids, in order to avoid a CPU be "present" but not "possible". Signed-off-by: Huacai Chen --- arch/loongarch/kernel/acpi.c | 22 ++++++++++++++++------ arch/loongarch/kernel/setup.c | 4 +++- arch/loongarch/kernel/smp.c | 7 +++---- 3 files changed, 22 insertions(+), 11 deletions(-) diff --git a/arch/loongarch/kernel/acpi.c b/arch/loongarch/kernel/acpi.c index 5cf59c617126..929a497c987e 100644 --- a/arch/loongarch/kernel/acpi.c +++ b/arch/loongarch/kernel/acpi.c @@ -57,15 +57,22 @@ void __iomem *acpi_os_ioremap(acpi_physical_address phys, acpi_size size) return ioremap_cache(phys, size); } +static int cpu_enumerated = 0; + #ifdef CONFIG_SMP static int set_processor_mask(u32 id, u32 flags) { - + int nr_cpus; int cpu, cpuid = id; - if (num_processors >= nr_cpu_ids) { - pr_warn(PREFIX "nr_cpus/possible_cpus limit of %i reached." - " processor 0x%x ignored.\n", nr_cpu_ids, cpuid); + if (!cpu_enumerated) + nr_cpus = NR_CPUS; + else + nr_cpus = nr_cpu_ids; + + if (num_processors >= nr_cpus) { + pr_warn(PREFIX "nr_cpus limit of %i reached." + " processor 0x%x ignored.\n", nr_cpus, cpuid); return -ENODEV; @@ -73,11 +80,13 @@ static int set_processor_mask(u32 id, u32 flags) if (cpuid == loongson_sysconf.boot_cpu_id) cpu = 0; else - cpu = cpumask_next_zero(-1, cpu_present_mask); + cpu = find_first_zero_bit(cpumask_bits(cpu_present_mask), NR_CPUS); + + if (!cpu_enumerated) + set_cpu_possible(cpu, true); if (flags & ACPI_MADT_ENABLED) { num_processors++; - set_cpu_possible(cpu, true); set_cpu_present(cpu, true); __cpu_number_map[cpuid] = cpu; __cpu_logical_map[cpu] = cpuid; @@ -138,6 +147,7 @@ static void __init acpi_process_madt(void) acpi_table_parse_madt(ACPI_MADT_TYPE_EIO_PIC, acpi_parse_eio_master, MAX_IO_PICS); + cpu_enumerated = 1; loongson_sysconf.nr_cpus = num_processors; } diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c index 3d048f1be143..0f0740f0be27 100644 --- a/arch/loongarch/kernel/setup.c +++ b/arch/loongarch/kernel/setup.c @@ -576,8 +576,10 @@ static void __init prefill_possible_map(void) for (i = 0; i < possible; i++) set_cpu_possible(i, true); - for (; i < NR_CPUS; i++) + for (; i < NR_CPUS; i++) { + set_cpu_present(i, false); set_cpu_possible(i, false); + } set_nr_cpu_ids(possible); } diff --git a/arch/loongarch/kernel/smp.c b/arch/loongarch/kernel/smp.c index 1436d2465939..03b2b7669cf5 100644 --- a/arch/loongarch/kernel/smp.c +++ b/arch/loongarch/kernel/smp.c @@ -271,11 +271,10 @@ static void __init fdt_smp_setup(void) if (cpuid >= nr_cpu_ids) continue; - if (cpuid == loongson_sysconf.boot_cpu_id) { + if (cpuid == loongson_sysconf.boot_cpu_id) cpu = 0; - } else { - cpu = cpumask_next_zero(-1, cpu_present_mask); - } + else + cpu = find_first_zero_bit(cpumask_bits(cpu_present_mask), NR_CPUS); num_processors++; set_cpu_possible(cpu, true);