Re: [PATCH v6 (proposal)] powerpc/cpu: enable nr_cpus for crash kernel
From: Christophe Leroy <hidden>
Date: 2024-01-25 19:45:55
Also in:
kexec
Hi, Le 22/05/2018 à 10:23, Pingfan Liu a écrit :
For kexec -p, the boot cpu can be not the cpu0, this causes the problem to alloc paca[]. In theory, there is no requirement to assign cpu's logical id as its present seq by device tree. But we have something like cpu_first_thread_sibling(), which makes assumption on the mapping inside a core. Hence partially changing the mapping, i.e. unbind the mapping of core while keep the mapping inside a core. After this patch, the core with boot-cpu will always be mapped into core 0. And at present, the code to discovery cpu spreads over two functions: early_init_dt_scan_cpus() and smp_setup_cpu_maps(). This patch tries to fold smp_setup_cpu_maps() into the "previous" one
This patch is pretty old and doesn't apply anymore. If still relevant can you please rebase and resubmit. Thanks Christophe
quoted hunk ↗ jump to hunk
Signed-off-by: Pingfan Liu <redacted> --- v5 -> v6: simplify the loop logic (Hope it can answer Benjamin's concern) concentrate the cpu recovery code to early stage (Hope it can answer Michael's concern) Todo: (if this method is accepted) fold the whole smp_setup_cpu_maps() arch/powerpc/include/asm/smp.h | 1 + arch/powerpc/kernel/prom.c | 123 ++++++++++++++++++++++++++++--------- arch/powerpc/kernel/setup-common.c | 58 ++--------------- drivers/of/fdt.c | 2 +- include/linux/of_fdt.h | 2 + 5 files changed, 103 insertions(+), 83 deletions(-)diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h index fac963e..80c7693 100644 --- a/arch/powerpc/include/asm/smp.h +++ b/arch/powerpc/include/asm/smp.h@@ -30,6 +30,7 @@ #include <asm/percpu.h> extern int boot_cpuid; +extern int threads_in_core; extern int spinning_secondaries; extern void cpu_die(void);diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c index 4922162..2ae0b4a 100644 --- a/arch/powerpc/kernel/prom.c +++ b/arch/powerpc/kernel/prom.c@@ -77,7 +77,6 @@ unsigned long tce_alloc_start, tce_alloc_end; u64 ppc64_rma_size; #endif static phys_addr_t first_memblock_size; -static int __initdata boot_cpu_count; static int __init early_parse_mem(char *p) {@@ -305,6 +304,14 @@ static void __init check_cpu_feature_properties(unsigned long node) } } +struct bootinfo { + int boot_thread_id; + unsigned int cpu_cnt; + int cpu_hwids[NR_CPUS]; + bool avail[NR_CPUS]; +}; +static struct bootinfo *bt_info; + static int __init early_init_dt_scan_cpus(unsigned long node, const char *uname, int depth, void *data)@@ -312,10 +319,12 @@ static int __init early_init_dt_scan_cpus(unsigned long node, const char *type = of_get_flat_dt_prop(node, "device_type", NULL); const __be32 *prop; const __be32 *intserv; - int i, nthreads; + int i, nthreads, maxidx; int len; - int found = -1; - int found_thread = 0; + int found_thread = -1; + struct bootinfo *info = data; + bool avail; + int rotate_cnt, id; /* We are scanning "cpu" nodes only */ if (type == NULL || strcmp(type, "cpu") != 0)@@ -325,8 +334,15 @@ static int __init early_init_dt_scan_cpus(unsigned long node, intserv = of_get_flat_dt_prop(node, "ibm,ppc-interrupt-server#s", &len); if (!intserv) intserv = of_get_flat_dt_prop(node, "reg", &len); + avail = of_fdt_device_is_available(initial_boot_params, node); +#if 0 + //todo + if (!avail) + avail = !of_fdt_property_match_string(node, + "enable-method", "spin-table"); +#endif - nthreads = len / sizeof(int); + threads_in_core = nthreads = len / sizeof(int); /* * Now see if any of these threads match our boot cpu.@@ -338,9 +354,10 @@ static int __init early_init_dt_scan_cpus(unsigned long node, * booted proc. */ if (fdt_version(initial_boot_params) >= 2) { + info->cpu_hwids[info->cpu_cnt] = + be32_to_cpu(intserv[i]); if (be32_to_cpu(intserv[i]) == fdt_boot_cpuid_phys(initial_boot_params)) { - found = boot_cpu_count; found_thread = i; } } else {@@ -351,22 +368,37 @@ static int __init early_init_dt_scan_cpus(unsigned long node, */ if (of_get_flat_dt_prop(node, "linux,boot-cpu", NULL) != NULL) - found = boot_cpu_count; + found_thread = info->cpu_cnt; } + info->avail[info->cpu_cnt] = avail; + #ifdef CONFIG_SMP /* logical cpu id is always 0 on UP kernels */ - boot_cpu_count++; + info->cpu_cnt++; #endif } /* Not the boot CPU */ - if (found < 0) + if (found_thread < 0) return 0; - DBG("boot cpu: logical %d physical %d\n", found, + /* always mapping boot-core to core 0 to cope with kexec -p */ + maxidx = info->cpu_cnt - 1; + rotate_cnt = nthreads; + while (rotate_cnt-- > 0) { + avail = info->avail[maxidx]; + id = info->cpu_hwids[maxidx]; + for (i = maxidx; i > 0; i--) { + info->avail[i] = info->avail[i - 1]; + info->cpu_hwids[i] = info->cpu_hwids[i - 1]; + } + info->avail[i] = avail; + info->cpu_hwids[i] = id; + } + + info->boot_thread_id = found_thread; + DBG("boot cpu: logical %d physical %d\n", found_thread, be32_to_cpu(intserv[found_thread])); - boot_cpuid = found; - set_hard_smp_processor_id(found, be32_to_cpu(intserv[found_thread])); /* * PAPR defines "logical" PVR values for cpus that@@ -675,6 +707,55 @@ static void __init tm_init(void) static void tm_init(void) { } #endif /* CONFIG_PPC_TRANSACTIONAL_MEM */ +static void early_setup_cpu_mapping(void) +{ + unsigned int cpu, cnt; + int nr_cpus_aligned; + + bt_info = __va(memblock_alloc(sizeof(struct bootinfo), + sizeof(unsigned long))); + memset(bt_info, 0, sizeof(struct bootinfo)); + bt_info->boot_thread_id = -1; + /* Retrieve CPU related informations from the flat tree + * (altivec support, boot CPU ID, ...) + */ + of_scan_flat_dt(early_init_dt_scan_cpus, bt_info); + + if (bt_info->boot_thread_id < 0) { + pr_err("Failed to identify boot CPU !\n"); + BUG(); + } + + boot_cpuid = bt_info->boot_thread_id; + /* work around subcore mode */ + nr_cpus_aligned = _ALIGN_UP(nr_cpu_ids, threads_in_core); + if (nr_cpus_aligned != nr_cpu_ids) { + pr_info("nr_cpus is forced to be aligned up from: %d to: %d\n", + nr_cpu_ids, nr_cpus_aligned); + nr_cpu_ids = nr_cpus_aligned; + } + cnt = (nr_cpu_ids < bt_info->cpu_cnt) ? nr_cpu_ids + : bt_info->cpu_cnt; + + allocate_pacas(); + for (cpu = 0; cpu < cnt; cpu++) { + set_cpu_present(cpu, bt_info->avail[cpu]); + DBG("set cpu present: %d -> hwid:%d\n", + cpu, bt_info->cpu_hwids[cpu]); + set_hard_smp_processor_id(cpu, bt_info->cpu_hwids[cpu]); + set_cpu_possible(cpu, true); + } + +#if defined(CONFIG_SMP) && defined(CONFIG_PPC64) + /* We'll later wait for secondaries to check in; there are + * NCPUS-1 non-boot CPUs :-) + */ + spinning_secondaries = bt_info->cpu_cnt - 1; +#endif + memblock_free(__pa(bt_info), sizeof(struct bootinfo)); + bt_info = NULL; +} + void __init early_init_devtree(void *params) { phys_addr_t limit;@@ -745,27 +826,11 @@ void __init early_init_devtree(void *params) * FIXME .. and the initrd too? */ move_device_tree(); - allocate_pacas(); - DBG("Scanning CPUs ...\n"); dt_cpu_ftrs_scan(); - /* Retrieve CPU related informations from the flat tree - * (altivec support, boot CPU ID, ...) - */ - of_scan_flat_dt(early_init_dt_scan_cpus, NULL); - if (boot_cpuid < 0) { - printk("Failed to identify boot CPU !\n"); - BUG(); - } - -#if defined(CONFIG_SMP) && defined(CONFIG_PPC64) - /* We'll later wait for secondaries to check in; there are - * NCPUS-1 non-boot CPUs :-) - */ - spinning_secondaries = boot_cpu_count - 1; -#endif + early_setup_cpu_mapping(); mmu_early_init_devtree();diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c index 66f7cc6..46d034a 100644 --- a/arch/powerpc/kernel/setup-common.c +++ b/arch/powerpc/kernel/setup-common.c@@ -86,7 +86,9 @@ struct machdep_calls *machine_id; EXPORT_SYMBOL(machine_id); int boot_cpuid = -1; +int threads_in_core = 1; EXPORT_SYMBOL_GPL(boot_cpuid); +EXPORT_SYMBOL_GPL(threads_in_core); /* * These are used in binfmt_elf.c to put aux entries on the stack@@ -460,61 +462,11 @@ void __init smp_setup_cpu_maps(void) { struct device_node *dn; int cpu = 0; - int nthreads = 1; - - DBG("smp_setup_cpu_maps()\n"); - - for_each_node_by_type(dn, "cpu") { - const __be32 *intserv; - __be32 cpu_be; - int j, len; - - DBG(" * %pOF...\n", dn); - - intserv = of_get_property(dn, "ibm,ppc-interrupt-server#s", - &len); - if (intserv) { - DBG(" ibm,ppc-interrupt-server#s -> %d threads\n", - nthreads); - } else { - DBG(" no ibm,ppc-interrupt-server#s -> 1 thread\n"); - intserv = of_get_property(dn, "reg", &len); - if (!intserv) { - cpu_be = cpu_to_be32(cpu); - intserv = &cpu_be; /* assume logical == phys */ - len = 4; - } - } - - nthreads = len / sizeof(int); - - 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"); - - set_cpu_present(cpu, avail); - set_hard_smp_processor_id(cpu, be32_to_cpu(intserv[j])); - set_cpu_possible(cpu, true); - cpu++; - } - - if (cpu >= nr_cpu_ids) { - of_node_put(dn); - break; - } - } /* If no SMT supported, nthreads is forced to 1 */ if (!cpu_has_feature(CPU_FTR_SMT)) { DBG(" SMT disabled ! nthreads forced to 1\n"); - nthreads = 1; + threads_in_core = 1; } #ifdef CONFIG_PPC64@@ -539,7 +491,7 @@ void __init smp_setup_cpu_maps(void) /* Double maxcpus for processors which have SMT capability */ if (cpu_has_feature(CPU_FTR_SMT)) - maxcpus *= nthreads; + maxcpus *= threads_in_core; if (maxcpus > nr_cpu_ids) { printk(KERN_WARNING@@ -565,7 +517,7 @@ void __init smp_setup_cpu_maps(void) * every CPU in the system. If that is not the case, then some code * here will have to be reworked */ - cpu_init_thread_core_maps(nthreads); + cpu_init_thread_core_maps(threads_in_core); /* Now that possible cpus are set, set nr_cpu_ids for later use */ setup_nr_cpu_ids();diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c index 84aa9d6..16d6b02 100644 --- a/drivers/of/fdt.c +++ b/drivers/of/fdt.c@@ -130,7 +130,7 @@ bool of_fdt_is_big_endian(const void *blob, unsigned long node) return false; } -static bool of_fdt_device_is_available(const void *blob, unsigned long node) +bool of_fdt_device_is_available(const void *blob, unsigned long node) { const char *status = fdt_getprop(blob, node, "status", NULL);diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h index b9cd9eb..28756c5 100644 --- a/include/linux/of_fdt.h +++ b/include/linux/of_fdt.h@@ -30,6 +30,8 @@ extern void *of_fdt_get_property(const void *blob, int *size); extern bool of_fdt_is_big_endian(const void *blob, unsigned long node); +extern bool of_fdt_device_is_available(const void *blob, + unsigned long node); extern int of_fdt_match(const void *blob, unsigned long node, const char *const *compat); extern void *of_fdt_unflatten_tree(const unsigned long *blob,