[PATCH v6 (proposal)] powerpc/cpu: enable nr_cpus for crash kernel
Pingfan Liu
piliu at redhat.com
Mon Jan 29 23:28:18 PST 2024
Hi Christophe,
The latest series is
https://lore.kernel.org/linuxppc-dev/20231017022806.4523-1-piliu@redhat.com/
And Michael has his implement on:
https://lore.kernel.org/all/20231229120107.2281153-3-mpe@ellerman.id.au/T/#m46128446bce1095631162a1927415733a3bf0633
Thanks,
Pingfan
On Fri, Jan 26, 2024 at 3:40 AM Christophe Leroy
<christophe.leroy at csgroup.eu> wrote:
>
> 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
>
> >
> > Signed-off-by: Pingfan Liu <kernelfans at gmail.com>
> > ---
> > 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,
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