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Date: Thu, 16 Aug 2018 09:54:03 +0530
From: Anup Patel <anup@...infault.org>
To: Atish Patra <atish.patra@....com>
Cc: palmer@...ive.com, linux-riscv@...ts.infradead.org,
Mark Rutland <mark.rutland@....com>,
Christoph Hellwig <hch@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>,
"linux-kernel@...r.kernel.org List" <linux-kernel@...r.kernel.org>,
Damien Le Moal <Damien.LeMoal@....com>
Subject: Re: [RFC PATCH 2/5] RISC-V: Use Linux logical cpu number instead of hartid
On Thu, Aug 16, 2018 at 5:26 AM, Atish Patra <atish.patra@....com> wrote:
> Setup the cpu_logical_map during boot. Moreover, every SBI call
> and PLIC context are based on the physical hartid. Use the logical
> cpu to hartid mapping to pass correct hartid to respective functions.
>
> Signed-off-by: Atish Patra <atish.patra@....com>
> ---
> arch/riscv/include/asm/tlbflush.h | 17 +++++++++++++----
> arch/riscv/kernel/cpu.c | 4 +++-
> arch/riscv/kernel/setup.c | 10 ++++++++++
> arch/riscv/kernel/smp.c | 24 +++++++++++++++---------
> arch/riscv/kernel/smpboot.c | 30 ++++++++++++++++++------------
> drivers/clocksource/riscv_timer.c | 12 ++++++++----
> drivers/irqchip/irq-sifive-plic.c | 11 +++++++----
> 7 files changed, 74 insertions(+), 34 deletions(-)
>
> diff --git a/arch/riscv/include/asm/tlbflush.h b/arch/riscv/include/asm/tlbflush.h
> index 85c2d8ba..ecfd9b0e 100644
> --- a/arch/riscv/include/asm/tlbflush.h
> +++ b/arch/riscv/include/asm/tlbflush.h
> @@ -16,6 +16,7 @@
> #define _ASM_RISCV_TLBFLUSH_H
>
> #include <linux/mm_types.h>
> +#include <asm/smp.h>
>
> /*
> * Flush entire local TLB. 'sfence.vma' implicitly fences with the instruction
> @@ -49,13 +50,21 @@ static inline void flush_tlb_range(struct vm_area_struct *vma,
>
> #include <asm/sbi.h>
>
> -#define flush_tlb_all() sbi_remote_sfence_vma(NULL, 0, -1)
> +static inline void remote_sfence_vma(struct cpumask *cmask, unsigned long start,
> + unsigned long size)
> +{
> + struct cpumask hmask;
> +
> + cpuid_to_hartid_mask(cmask, &hmask);
> + sbi_remote_sfence_vma(hmask.bits, start, size);
> +}
> +
> +#define flush_tlb_all() remote_sfence_vma(NULL, 0, -1)
> #define flush_tlb_page(vma, addr) flush_tlb_range(vma, addr, 0)
> #define flush_tlb_range(vma, start, end) \
> - sbi_remote_sfence_vma(mm_cpumask((vma)->vm_mm)->bits, \
> - start, (end) - (start))
> + remote_sfence_vma(mm_cpumask((vma)->vm_mm), start, (end) - (start))
> #define flush_tlb_mm(mm) \
> - sbi_remote_sfence_vma(mm_cpumask(mm)->bits, 0, -1)
> + remote_sfence_vma(mm_cpumask(mm), 0, -1)
>
> #endif /* CONFIG_SMP */
>
> diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
> index ca6c81e5..f8a18ace 100644
> --- a/arch/riscv/kernel/cpu.c
> +++ b/arch/riscv/kernel/cpu.c
> @@ -14,6 +14,7 @@
> #include <linux/init.h>
> #include <linux/seq_file.h>
> #include <linux/of.h>
> +#include <asm/smp.h>
>
> /* Return -1 if not a valid hart */
> int riscv_of_processor_hart(struct device_node *node)
> @@ -79,7 +80,8 @@ static void c_stop(struct seq_file *m, void *v)
> static int c_show(struct seq_file *m, void *v)
> {
> unsigned long hart_id = (unsigned long)v - 1;
> - struct device_node *node = of_get_cpu_node(hart_id, NULL);
> + struct device_node *node = of_get_cpu_node(cpu_logical_map(hart_id),
> + NULL);
The hart_id is misleading name here. It should be cpu_id. Please replace
all instances of hart_id with cpu_id and where hard ID is to be displayed
use cpu_logical_map(cpu_id).
> const char *compat, *isa, *mmu;
>
> seq_printf(m, "hart\t: %lu\n", hart_id);
> diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> index e21ed481..97b586f8 100644
> --- a/arch/riscv/kernel/setup.c
> +++ b/arch/riscv/kernel/setup.c
> @@ -84,6 +84,16 @@ atomic_t hart_lottery;
>
> u64 __cpu_logical_map[NR_CPUS];
>
> +void __init smp_setup_processor_id(void)
> +{
> + int cpu = smp_processor_id();
> +
> + cpu_logical_map(0) = cpu;
I think this should be:
cpu_logical_map(cpu) = hart_id;
Here hart_id for boot CPU will be value of a0 register passed at boot-time.
> +
> + /* Change the boot cpu ID in thread_info */
> + current->thread_info.cpu = 0;
> +}
> +
> #ifdef CONFIG_BLK_DEV_INITRD
> static void __init setup_initrd(void)
> {
> diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
> index d55379ee..4ab70480 100644
> --- a/arch/riscv/kernel/smp.c
> +++ b/arch/riscv/kernel/smp.c
> @@ -97,14 +97,18 @@ void riscv_software_interrupt(void)
> static void
> send_ipi_message(const struct cpumask *to_whom, enum ipi_message_type operation)
> {
> - int i;
> + int cpuid, hartid;
> + struct cpumask hartid_mask;
>
> + cpumask_clear(&hartid_mask);
> mb();
> - for_each_cpu(i, to_whom)
> - set_bit(operation, &ipi_data[i].bits);
> -
> + for_each_cpu(cpuid, to_whom) {
> + set_bit(operation, &ipi_data[cpuid].bits);
> + hartid = cpu_logical_map(cpuid);
> + cpumask_set_cpu(hartid, &hartid_mask);
> + }
> mb();
> - sbi_send_ipi(cpumask_bits(to_whom));
> + sbi_send_ipi(cpumask_bits(&hartid_mask));
> }
>
> void arch_send_call_function_ipi_mask(struct cpumask *mask)
> @@ -146,7 +150,7 @@ void smp_send_reschedule(int cpu)
> void flush_icache_mm(struct mm_struct *mm, bool local)
> {
> unsigned int cpu;
> - cpumask_t others, *mask;
> + cpumask_t others, hmask, *mask;
>
> preempt_disable();
>
> @@ -164,9 +168,11 @@ void flush_icache_mm(struct mm_struct *mm, bool local)
> */
> cpumask_andnot(&others, mm_cpumask(mm), cpumask_of(cpu));
> local |= cpumask_empty(&others);
> - if (mm != current->active_mm || !local)
> - sbi_remote_fence_i(others.bits);
> - else {
> + if (mm != current->active_mm || !local) {
> + cpumask_clear(&hmask);
> + cpuid_to_hartid_mask(&others, &hmask);
> + sbi_remote_fence_i(hmask.bits);
> + } else {
> /*
> * It's assumed that at least one strongly ordered operation is
> * performed on this hart between setting a hart's cpumask bit
> diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
> index 56abab6a..6ab2bb1b 100644
> --- a/arch/riscv/kernel/smpboot.c
> +++ b/arch/riscv/kernel/smpboot.c
> @@ -50,27 +50,33 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
> void __init setup_smp(void)
> {
> struct device_node *dn = NULL;
> - int hart, im_okay_therefore_i_am = 0;
> + int hart, found_boot_cpu = 0;
> + int cpuid = 1;
>
> while ((dn = of_find_node_by_type(dn, "cpu"))) {
> hart = riscv_of_processor_hart(dn);
> - if (hart >= 0) {
> - set_cpu_possible(hart, true);
> - set_cpu_present(hart, true);
> - if (hart == smp_processor_id()) {
> - BUG_ON(im_okay_therefore_i_am);
> - im_okay_therefore_i_am = 1;
> - }
> +
> + if (hart < 0)
> + continue;
> + if (hart == cpu_logical_map(0)) {
> + BUG_ON(found_boot_cpu);
> + found_boot_cpu = 1;
> + continue;
> }
> +
> + cpu_logical_map(cpuid) = hart;
> + set_cpu_possible(cpuid, true);
> + set_cpu_present(cpuid, true);
> + cpuid++;
> }
>
> - BUG_ON(!im_okay_therefore_i_am);
> + BUG_ON(!found_boot_cpu);
> }
>
> int __cpu_up(unsigned int cpu, struct task_struct *tidle)
> {
> + int hartid = cpu_logical_map(cpu);
> tidle->thread_info.cpu = cpu;
> -
> /*
> * On RISC-V systems, all harts boot on their own accord. Our _start
> * selects the first hart to boot the kernel and causes the remainder
> @@ -79,8 +85,8 @@ int __cpu_up(unsigned int cpu, struct task_struct *tidle)
> * the spinning harts that they can continue the boot process.
> */
> smp_mb();
> - __cpu_up_stack_pointer[cpu] = task_stack_page(tidle) + THREAD_SIZE;
> - __cpu_up_task_pointer[cpu] = tidle;
> + __cpu_up_stack_pointer[hartid] = task_stack_page(tidle) + THREAD_SIZE;
> + __cpu_up_task_pointer[hartid] = tidle;
>
> while (!cpu_online(cpu))
> cpu_relax();
> diff --git a/drivers/clocksource/riscv_timer.c b/drivers/clocksource/riscv_timer.c
> index 4e8b347e..f1f205e5 100644
> --- a/drivers/clocksource/riscv_timer.c
> +++ b/drivers/clocksource/riscv_timer.c
> @@ -8,6 +8,7 @@
> #include <linux/cpu.h>
> #include <linux/delay.h>
> #include <linux/irq.h>
> +#include <asm/smp.h>
> #include <asm/sbi.h>
>
> /*
> @@ -84,13 +85,16 @@ void riscv_timer_interrupt(void)
>
> static int __init riscv_timer_init_dt(struct device_node *n)
> {
> - int cpu_id = riscv_of_processor_hart(n), error;
> + int cpuid, hartid, error;
> struct clocksource *cs;
>
> - if (cpu_id != smp_processor_id())
> + hartid = riscv_of_processor_hart(n);
> + cpuid = riscv_hartid_to_cpuid(hartid);
> +
> + if (cpuid != smp_processor_id())
> return 0;
>
> - cs = per_cpu_ptr(&riscv_clocksource, cpu_id);
> + cs = per_cpu_ptr(&riscv_clocksource, cpuid);
> clocksource_register_hz(cs, riscv_timebase);
>
> error = cpuhp_setup_state(CPUHP_AP_RISCV_TIMER_STARTING,
> @@ -98,7 +102,7 @@ static int __init riscv_timer_init_dt(struct device_node *n)
> riscv_timer_starting_cpu, riscv_timer_dying_cpu);
> if (error)
> pr_err("RISCV timer register failed [%d] for cpu = [%d]\n",
> - error, cpu_id);
> + error, cpuid);
> return error;
> }
>
> diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
> index 298685e5..2eb2e78c 100644
> --- a/drivers/irqchip/irq-sifive-plic.c
> +++ b/drivers/irqchip/irq-sifive-plic.c
> @@ -15,6 +15,7 @@
> #include <linux/of_irq.h>
> #include <linux/platform_device.h>
> #include <linux/spinlock.h>
> +#include <asm/smp.h>
>
> /*
> * This driver implements a version of the RISC-V PLIC with the actual layout
> @@ -93,10 +94,11 @@ static inline void plic_toggle(int ctxid, int hwirq, int enable)
> static inline void plic_irq_toggle(struct irq_data *d, int enable)
> {
> int cpu;
> + struct plic_handler *handler;
>
> writel(enable, plic_regs + PRIORITY_BASE + d->hwirq * PRIORITY_PER_ID);
> for_each_cpu(cpu, irq_data_get_affinity_mask(d)) {
> - struct plic_handler *handler = per_cpu_ptr(&plic_handlers, cpu);
> + handler = per_cpu_ptr(&plic_handlers, cpu);
>
> if (handler->present)
> plic_toggle(handler->ctxid, d->hwirq, enable);
> @@ -217,7 +219,7 @@ static int __init plic_init(struct device_node *node,
> struct of_phandle_args parent;
> struct plic_handler *handler;
> irq_hw_number_t hwirq;
> - int cpu;
> + int cpu, hartid;
>
> if (of_irq_parse_one(node, i, &parent)) {
> pr_err("failed to parse parent for context %d.\n", i);
> @@ -228,12 +230,13 @@ static int __init plic_init(struct device_node *node,
> if (parent.args[0] == -1)
> continue;
>
> - cpu = plic_find_hart_id(parent.np);
> - if (cpu < 0) {
> + hartid = plic_find_hart_id(parent.np);
> + if (hartid < 0) {
> pr_warn("failed to parse hart ID for context %d.\n", i);
> continue;
> }
>
> + cpu = riscv_hartid_to_cpuid(hartid);
> handler = per_cpu_ptr(&plic_handlers, cpu);
> handler->present = true;
> handler->ctxid = i;
> --
> 2.7.4
>
Regards,
Anup
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