*** Idea *** For kexec -p, the boot cpu can be not the cpu0, this causes the problem of allocating memory for paca_ptrs[]. However, in theory, there is no requirement to assign cpu's logical id as its present sequence in the device tree. But there is something like cpu_first_thread_sibling(), which makes assumption on the mapping inside a core. Hence partially loosening the mapping, i.e. unbind the mapping of core while keep the mapping inside a core.
*** Implement *** At this early stage, there are plenty of memory to utilize. Hence, this patch allocates interim memory to link the cpu info on a list, then reorder cpus by changing the list head. As a result, there is a rotate shift between the sequence number in dt and the cpu logical number. *** Result *** After this patch, a boot-cpu's logical id will always be mapped into the range [0,threads_per_core). Besides this, at this phase, all threads in the boot core are forced to be onlined. This restriction will be lifted in a later patch with extra effort. Signed-off-by: Pingfan Liu <pi...@redhat.com> Cc: Michael Ellerman <m...@ellerman.id.au> Cc: Nicholas Piggin <npig...@gmail.com> Cc: Christophe Leroy <christophe.le...@csgroup.eu> Cc: Mahesh Salgaonkar <mah...@linux.ibm.com> Cc: Wen Xiong <wenxi...@us.ibm.com> Cc: Baoquan He <b...@redhat.com> Cc: Ming Lei <ming....@redhat.com> Cc: Sourabh Jain <sourabhj...@linux.ibm.com> Cc: Hari Bathini <hbath...@linux.ibm.com> Cc: ke...@lists.infradead.org To: linuxppc-dev@lists.ozlabs.org --- arch/powerpc/kernel/prom.c | 25 +++++---- arch/powerpc/kernel/setup-common.c | 84 +++++++++++++++++++++++------- 2 files changed, 82 insertions(+), 27 deletions(-) diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c index ec82f5bda908..7ed9034912ca 100644 --- a/arch/powerpc/kernel/prom.c +++ b/arch/powerpc/kernel/prom.c @@ -76,7 +76,9 @@ u64 ppc64_rma_size; unsigned int boot_cpu_node_count __ro_after_init; #endif static phys_addr_t first_memblock_size; +#ifdef CONFIG_SMP static int __initdata boot_cpu_count; +#endif static int __init early_parse_mem(char *p) { @@ -331,8 +333,7 @@ static int __init early_init_dt_scan_cpus(unsigned long node, const __be32 *intserv; int i, nthreads; int len; - int found = -1; - int found_thread = 0; + bool found = false; /* We are scanning "cpu" nodes only */ if (type == NULL || strcmp(type, "cpu") != 0) @@ -355,8 +356,15 @@ static int __init early_init_dt_scan_cpus(unsigned long node, for (i = 0; i < nthreads; i++) { if (be32_to_cpu(intserv[i]) == fdt_boot_cpuid_phys(initial_boot_params)) { - found = boot_cpu_count; - found_thread = i; + /* + * always map the boot-cpu logical id into the + * range of [0, thread_per_core) + */ + boot_cpuid = i; + found = true; + /* This forces all threads in a core to be online */ + if (nr_cpu_ids % nthreads != 0) + set_nr_cpu_ids(ALIGN(nr_cpu_ids, nthreads)); } #ifdef CONFIG_SMP /* logical cpu id is always 0 on UP kernels */ @@ -365,14 +373,13 @@ static int __init early_init_dt_scan_cpus(unsigned long node, } /* Not the boot CPU */ - if (found < 0) + if (!found) return 0; - DBG("boot cpu: logical %d physical %d\n", found, - be32_to_cpu(intserv[found_thread])); - boot_cpuid = found; + DBG("boot cpu: logical %d physical %d\n", boot_cpuid, + be32_to_cpu(intserv[boot_cpuid])); - boot_cpu_hwid = be32_to_cpu(intserv[found_thread]); + boot_cpu_hwid = be32_to_cpu(intserv[boot_cpuid]); /* * PAPR defines "logical" PVR values for cpus that diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c index 707f0490639d..9802c7e5ee2f 100644 --- a/arch/powerpc/kernel/setup-common.c +++ b/arch/powerpc/kernel/setup-common.c @@ -36,6 +36,7 @@ #include <linux/of_irq.h> #include <linux/hugetlb.h> #include <linux/pgtable.h> +#include <linux/list.h> #include <asm/io.h> #include <asm/paca.h> #include <asm/processor.h> @@ -425,6 +426,13 @@ static void __init cpu_init_thread_core_maps(int tpc) u32 *cpu_to_phys_id = NULL; +struct interrupt_server_node { + struct list_head node; + bool avail; + int len; + __be32 intserv[]; +}; + /** * setup_cpu_maps - initialize the following cpu maps: * cpu_possible_mask @@ -446,11 +454,16 @@ u32 *cpu_to_phys_id = NULL; void __init smp_setup_cpu_maps(void) { struct device_node *dn; - int cpu = 0; - int nthreads = 1; + int shift = 0, cpu = 0; + int j, nthreads = 1; + int len; + struct interrupt_server_node *intserv_node, *n; + struct list_head *bt_node, head; + bool avail, found_boot_cpu = false; DBG("smp_setup_cpu_maps()\n"); + INIT_LIST_HEAD(&head); cpu_to_phys_id = memblock_alloc(nr_cpu_ids * sizeof(u32), __alignof__(u32)); if (!cpu_to_phys_id) @@ -460,7 +473,6 @@ void __init smp_setup_cpu_maps(void) for_each_node_by_type(dn, "cpu") { const __be32 *intserv; __be32 cpu_be; - int j, len; DBG(" * %pOF...\n", dn); @@ -480,29 +492,65 @@ void __init smp_setup_cpu_maps(void) } } - nthreads = len / sizeof(int); + avail = of_device_is_available(dn); + if (!avail) + avail = !of_property_match_string(dn, + "enable-method", "spin-table"); - for (j = 0; j < nthreads && cpu < nr_cpu_ids; j++) { - bool avail; - DBG(" thread %d -> cpu %d (hard id %d)\n", - j, cpu, be32_to_cpu(intserv[j])); - - avail = of_device_is_available(dn); - if (!avail) - avail = !of_property_match_string(dn, - "enable-method", "spin-table"); + intserv_node = memblock_alloc(sizeof(struct interrupt_server_node) + len, + __alignof__(u32)); + if (!intserv_node) + panic("%s: Failed to allocate %zu bytes align=0x%zx\n", + __func__, + sizeof(struct interrupt_server_node) + len, + __alignof__(u32)); + intserv_node->len = len; + memcpy(intserv_node->intserv, intserv, len); + intserv_node->avail = avail; + list_add_tail(&intserv_node->node, &head); + + if (!found_boot_cpu) { + nthreads = len / sizeof(int); + for (j = 0 ; j < nthreads; j++) { + if (be32_to_cpu(intserv[j]) == boot_cpu_hwid) { + bt_node = &intserv_node->node; + found_boot_cpu = true; + /* + * Record the round-shift between dt + * seq and cpu logical number + */ + shift = cpu - j; + break; + } + + cpu++; + } + } + } + cpu = 0; + list_del_init(&head); + /* Select the primary thread, the boot cpu's slibing, as the logic 0 */ + list_add_tail(&head, bt_node); + pr_info("the round shift between dt seq and the cpu logic number: %d\n", shift); + list_for_each_entry(intserv_node, &head, node) { + + avail = intserv_node->avail; + nthreads = intserv_node->len / sizeof(int); + for (j = 0; j < nthreads && cpu < nr_cpu_ids; j++) { set_cpu_present(cpu, avail); set_cpu_possible(cpu, true); - cpu_to_phys_id[cpu] = be32_to_cpu(intserv[j]); + cpu_to_phys_id[cpu] = be32_to_cpu(intserv_node->intserv[j]); + DBG(" thread %d -> cpu %d (hard id %d)\n", + j, cpu, be32_to_cpu(intserv_node->intserv[j])); cpu++; } + } - if (cpu >= nr_cpu_ids) { - of_node_put(dn); - break; - } + list_for_each_entry_safe(intserv_node, n, &head, node) { + len = sizeof(struct interrupt_server_node) + intserv_node->len; + memblock_free(intserv_node, len); } /* If no SMT supported, nthreads is forced to 1 */ -- 2.31.1