Re: [PATCH V3 10/20] RISC-V: smpboot: Add ACPI support in smp_setup()

Andrew Jones
2023-03-03T15:49:29Z

On Fri, Mar 03, 2023 at 07:06:37PM +0530, Sunil V L wrote:
> Enable SMP boot on ACPI based platforms by using the RINTC
> structures in the MADT table.
>
> Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
> ---
> arch/riscv/kernel/smpboot.c | 72 ++++++++++++++++++++++++++++++++++++-
> 1 file changed, 71 insertions(+), 1 deletion(-)
>
> diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
> index 26214ddefaa4..27047322d3bb 100644
> --- a/arch/riscv/kernel/smpboot.c
> +++ b/arch/riscv/kernel/smpboot.c
> @@ -8,6 +8,7 @@
> * Copyright (C) 2017 SiFive
> */
>
> +#include <linux/acpi.h>
> #include <linux/arch_topology.h>
> #include <linux/module.h>
> #include <linux/init.h>
> @@ -70,6 +71,72 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
> }
> }
>
> +#ifdef CONFIG_ACPI
> +static unsigned int cpu_count = 1;
> +
> +static int __init acpi_parse_rintc(union acpi_subtable_headers *header, const unsigned long end)
> +{
> + unsigned long hart;
> + static bool found_boot_cpu;
> + struct acpi_madt_rintc *processor = (struct acpi_madt_rintc *)header;
> +
> + /*
> + * Each RINTC structure in MADT will have a flag. If ACPI_MADT_ENABLED
> + * bit in the flag is not enabled, it means OS should not try to enable
> + * the cpu to which RINTC belongs.
> + */
> + if (!(processor->flags & ACPI_MADT_ENABLED))
> + return 0;
> +
> + if (BAD_MADT_ENTRY(processor, end))
> + return -EINVAL;
> +
> + acpi_table_print_madt_entry(&header->common);
> +
> + hart = processor->hart_id;
> + if (hart == INVALID_HARTID) {
> + pr_warn("Invalid hartid\n");
> + return 0;
> + }
> +
> + if (hart == cpuid_to_hartid_map(0)) {
> + BUG_ON(found_boot_cpu);
> + found_boot_cpu = true;
> + early_map_cpu_to_node(0, NUMA_NO_NODE);

We should have kept

static inline int acpi_numa_get_nid(unsigned int cpu) { return NUMA_NO_NODE; }

and only dropped the

#ifdef CONFIG_ACPI_NUMA
int acpi_numa_get_nid(unsigned int cpu);
#else
...
#endif

> + return 0;
> + }
> +
> + if (cpu_count >= NR_CPUS) {
> + pr_warn("NR_CPUS is too small for the number of ACPI tables.\n");
> + return 0;
> + }
> +
> + cpuid_to_hartid_map(cpu_count) = hart;
> + early_map_cpu_to_node(cpu_count, NUMA_NO_NODE);
> + cpu_count++;
> +
> + return 0;
> +}
> +
> +static void __init acpi_parse_and_init_cpus(void)
> +{
> + int cpuid;
> +
> + cpu_set_ops(0);
> +
> + acpi_table_parse_madt(ACPI_MADT_TYPE_RINTC, acpi_parse_rintc, 0);
> +
> + for (cpuid = 1; cpuid < nr_cpu_ids; cpuid++) {
> + if (cpuid_to_hartid_map(cpuid) != INVALID_HARTID) {
> + cpu_set_ops(cpuid);
> + set_cpu_possible(cpuid, true);
> + }
> + }
> +}
> +#else
> +#define acpi_parse_and_init_cpus(...) do { } while (0)
> +#endif
> +
> static void __init of_parse_and_init_cpus(void)
> {
> struct device_node *dn;
> @@ -118,7 +185,10 @@ static void __init of_parse_and_init_cpus(void)
>
> void __init setup_smp(void)
> {
> - of_parse_and_init_cpus();
> + if (acpi_disabled)
> + of_parse_and_init_cpus();
> + else
> + acpi_parse_and_init_cpus();
> }
>
> static int start_secondary_cpu(int cpu, struct task_struct *tidle)
> --
> 2.34.1
>

Thanks,
drew