[PATCH] arm64: Support hard limit of cpu count by nr_cpus
From: Suzuki.Poulose@arm.com (Suzuki K Poulose)
Date: 2016-08-05 10:19:12
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
On 05/08/16 10:58, Kefeng Wang wrote:
quoted hunk ↗ jump to hunk
On 2016/8/5 16:32, Will Deacon wrote:quoted
On Fri, Aug 05, 2016 at 02:03:55PM +0800, Kefeng Wang wrote:quoted
Enable the hard limit of cpu count by nr_cpus on arm64. The code is borrowed from MIPS. Reported-by: Shiyuan Hu <redacted> Signed-off-by: Kefeng Wang <redacted> --- arch/arm64/kernel/setup.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c index 536dce2..597b777 100644 --- a/arch/arm64/kernel/setup.c +++ b/arch/arm64/kernel/setup.c@@ -224,6 +224,21 @@ static void __init request_standard_resources(void) u64 __cpu_logical_map[NR_CPUS] = { [0 ... NR_CPUS-1] = INVALID_HWID }; +static void __init prefill_possible_map(void) +{ + int i, possible = num_possible_cpus(); + + if (possible > nr_cpu_ids) + possible = nr_cpu_ids; + + for (i = 0; i < possible; i++) + set_cpu_possible(i, true); + for (; i < NR_CPUS; i++) + set_cpu_possible(i, false); + + nr_cpu_ids = possible; +}Shouldn't we just avoid marking those CPUs as possible in smp_cpu_setup, rather than rewriting things later on?How about this one, From 0965eebecbc5aea0473df0cb45d32b2fccf72a9a Mon Sep 17 00:00:00 2001 From: Kefeng Wang <redacted> Date: Fri, 5 Aug 2016 17:44:33 +0800 Subject: [PATCH v2] arm64: Support hard limit of cpu count by nr_cpus Enable the hard limit of cpu count by set boot options nr_cpus=x on arm64. Signed-off-by: Kefeng Wang <redacted> --- arch/arm64/kernel/smp.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index 76a6d92..0ac3ff5 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c@@ -496,7 +496,10 @@ static int __init smp_cpu_setup(int cpu) if (cpu_ops[cpu]->cpu_init(cpu)) return -ENODEV; - set_cpu_possible(cpu, true); + if (cpu < nr_cpu_ids) + set_cpu_possible(cpu, true); + else + return -EINVAL; return 0; }
Or is this even better ?
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 490db85..dbd6a5e 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c@@ -659,9 +659,9 @@ void __init smp_init_cpus(void) acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_INTERRUPT, acpi_parse_gic_cpu_interface, 0); - if (cpu_count > NR_CPUS) + if (cpu_count > nr_cpu_ids) pr_warn("no. of cores (%d) greater than configured maximum of %d - clipping\n", - cpu_count, NR_CPUS); + cpu_count, nr_cpu_ids); if (!bootcpu_valid) { pr_err("missing boot CPU MPIDR, not enabling secondaries\n");
@@ -675,7 +675,7 @@ void __init smp_init_cpus(void) * with entries in cpu_logical_map while initializing the cpus. * If the cpu set-up fails, invalidate the cpu_logical_map entry. */ - for (i = 1; i < NR_CPUS; i++) { + for (i = 1; i < nr_cpu_ids; i++) { if (cpu_logical_map(i) != INVALID_HWID) { if (smp_cpu_setup(i)) cpu_logical_map(i) = INVALID_HWID;
Cheers Suzuki