[PATCHv7 2/4] powerpc/setup: Loosen the mapping between cpu logical id and its seq in dt
Wen Xiong
wenxiong at us.ibm.com
Thu Sep 28 13:36:14 PDT 2023
Hi Pingfan,
+ 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[j]));
Intserv is not defined. Should "be32_to_cpu(intserv_node->intserv[j])?
cpu++;
}
+ }
-----Original Message-----
From: Pingfan Liu <piliu at redhat.com>
Sent: Monday, September 25, 2023 2:54 AM
To: linuxppc-dev at lists.ozlabs.org
Cc: Pingfan Liu <piliu at redhat.com>; Michael Ellerman <mpe at ellerman.id.au>; Nicholas Piggin <npiggin at gmail.com>; Christophe Leroy <christophe.leroy at csgroup.eu>; Mahesh Salgaonkar <mahesh at linux.ibm.com>; Wen Xiong <wenxiong at us.ibm.com>; Baoquan He <bhe at redhat.com>; Ming Lei <ming.lei at redhat.com>; kexec at lists.infradead.org
Subject: [EXTERNAL] [PATCHv7 2/4] powerpc/setup: Loosen the mapping between cpu logical id and its seq in dt
*** 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 <piliu at redhat.com>
Cc: Michael Ellerman <mpe at ellerman.id.au>
Cc: Nicholas Piggin <npiggin at gmail.com>
Cc: Christophe Leroy <christophe.leroy at csgroup.eu>
Cc: Mahesh Salgaonkar <mahesh at linux.ibm.com>
Cc: Wen Xiong <wenxiong at us.ibm.com>
Cc: Baoquan He <bhe at redhat.com>
Cc: Ming Lei <ming.lei at redhat.com>
Cc: kexec at lists.infradead.org
To: linuxppc-dev at lists.ozlabs.org
---
arch/powerpc/kernel/prom.c | 25 +++++----
arch/powerpc/kernel/setup-common.c | 87 +++++++++++++++++++++++-------
2 files changed, 85 insertions(+), 27 deletions(-)
diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c index ec82f5bda908..87272a2d8c10 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 works around the hole in paca_ptrs[]. */
+ if (nr_cpu_ids < nthreads)
+ set_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 1b19a9815672..f6d32324b5a5 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -36,6 +36,7 @@
#include <linux/of_platform.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 +492,68 @@ void __init smp_setup_cpu_maps(void)
}
}
- nthreads = len / sizeof(int);
-
- for (j = 0; j < nthreads && cpu < nr_cpu_ids; j++) {
- bool avail;
+ avail = of_device_is_available(dn);
+ if (!avail)
+ avail = !of_property_match_string(dn,
+ "enable-method", "spin-table");
- 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->intserv = (__be32 *)((char *)intserv_node +
+ sizeof(struct interrupt_server_node));
+ intserv_node->len = len;
+ memcpy(intserv_node->intserv, intserv, len);
+ intserv_node->avail = avail;
+ INIT_LIST_HEAD(&intserv_node->node);
+ 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[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
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