[RFC part2 PATCH 2/9] ARM64 / ACPI: Prefill cpu possible/present maps and map logical cpu id to APIC id

Hanjun Guo
2013-12-03T16:40:05Z

When boot the kernel with MADT, the cpu possible and present maps should be
prefilled for cpu topology and acpi based cpu hot-plug.

The logic cpu id maps to APIC id (GIC id) is also implemented, it is needed
for acpi processor drivers.

Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
---
arch/arm64/include/asm/acpi.h | 10 ++--
arch/arm64/kernel/setup.c | 2 +
arch/arm64/kernel/smp.c | 2 +
drivers/acpi/plat/arm-core.c | 118 +++++++++++++++++++++++++++++++++++++++++
4 files changed, 129 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
index be2951c..423a32c 100644
--- a/arch/arm64/include/asm/acpi.h
+++ b/arch/arm64/include/asm/acpi.h
@@ -76,9 +76,6 @@ static inline void acpi_disable_pci(void)
/* FIXME: this function should be moved to topology.h when it's ready */
void arch_fix_phys_package_id(int num, u32 slot);

-/* temperally define -1 to make acpi core compilerable */
-#define cpu_physical_id(cpu) -1
-
/* Low-level suspend routine. */
extern int (*acpi_suspend_lowlevel)(void);
#define acpi_wakeup_address (0)
@@ -86,6 +83,13 @@ extern int (*acpi_suspend_lowlevel)(void);
#define MAX_GIC_CPU_INTERFACE 256
#define MAX_GIC_DISTRIBUTOR 1 /* should be the same as MAX_GIC_NR */

+/* map logic cpu id to physical GIC id */
+extern int arm_cpu_to_apicid[NR_CPUS];
+extern int boot_cpu_apic_id;
+#define cpu_physical_id(cpu) arm_cpu_to_apicid[cpu]
+
+extern void prefill_possible_map(void);
+
#else /* !CONFIG_ACPI */
#define acpi_disabled 1 /* ACPI sometimes enabled on ARM */
#define acpi_noirq 1 /* ACPI sometimes enabled on ARM */
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 8199360..08f11e2 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -231,7 +231,9 @@ void __init setup_arch(char **cmdline_p)
*/
acpi_boot_table_init();
early_acpi_boot_init();
+ boot_cpu_apic_id = read_cpuid_mpidr() & MPIDR_HWID_BITMASK;
acpi_boot_init();
+ prefill_possible_map();

paging_init();
request_standard_resources();
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index a0c2ca6..1428024 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -420,7 +420,9 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
if (err)
continue;

+#ifndef CONFIG_ACPI
set_cpu_present(cpu, true);
+#endif
max_cpus--;
}
}
diff --git a/drivers/acpi/plat/arm-core.c b/drivers/acpi/plat/arm-core.c
index 45ff625..8527ecc 100644
--- a/drivers/acpi/plat/arm-core.c
+++ b/drivers/acpi/plat/arm-core.c
@@ -58,6 +58,13 @@ EXPORT_SYMBOL(acpi_pci_disabled);
*/
static u64 acpi_lapic_addr __initdata;

+/* available_cpus here means enabled cpu in MADT */
+int available_cpus;
+
+/* Map logic cpu id to physical GIC id. */
+int arm_cpu_to_apicid[NR_CPUS] = { [0 ... NR_CPUS-1] = -1 };
+int boot_cpu_apic_id = -1;
+
#define BAD_MADT_ENTRY(entry, end) ( \
(!entry) || (unsigned long)entry + sizeof(*entry) > end || \
((struct acpi_subtable_header *)entry)->length < sizeof(*entry))
@@ -142,6 +149,39 @@ static int __init acpi_parse_madt(struct acpi_table_header *table)
* Please refer to chapter5.2.12.14/15 of ACPI 5.0
*/

+static void acpi_register_gic_cpu_interface(int id, u8 enabled)
+{
+ int cpu;
+
+ if (id >= MAX_GIC_CPU_INTERFACE) {
+ pr_info(PREFIX "skipped apicid that is too big\n");
+ return;
+ }
+
+ total_cpus++;
+ if (!enabled)
+ return;
+
+ available_cpus++;
+
+ /* allocate a logic cpu id for the new comer */
+ if (boot_cpu_apic_id == id) {
+ /*
+ * boot_cpu_init() already hold bit 0 in cpu_present_mask
+ * for BSP, no need to allocte again.
+ */
+ cpu = 0;
+ } else {
+ cpu = cpumask_next_zero(-1, cpu_present_mask);
+ }
+
+ /* map the logic cpu id to APIC id */
+ arm_cpu_to_apicid[cpu] = id;
+
+ set_cpu_present(cpu, true);
+ set_cpu_possible(cpu, true);
+}
+
static int __init
acpi_parse_gic(struct acpi_subtable_header *header, const unsigned long end)
{
@@ -154,6 +194,16 @@ acpi_parse_gic(struct acpi_subtable_header *header, const unsigned long end)

acpi_table_print_madt_entry(header);

+ /*
+ * We need to register disabled CPU as well to permit
+ * counting disabled CPUs. This allows us to size
+ * cpus_possible_map more accurately, to permit
+ * to not preallocating memory for all NR_CPUS
+ * when we use CPU hotplug.
+ */
+ acpi_register_gic_cpu_interface(processor->gic_id,
+ processor->flags & ACPI_MADT_ENABLED);
+
return 0;
}

@@ -196,6 +246,19 @@ static int __init acpi_parse_madt_gic_entries(void)
return count;
}

+#ifdef CONFIG_SMP
+ if (available_cpus == 0) {
+ pr_info(PREFIX "Found 0 CPUs; assuming 1\n");
+ /* FIXME: should be the real GIC id read from hardware */
+ arm_cpu_to_apicid[available_cpus] = 0;
+ available_cpus = 1; /* We've got at least one of these */
+ }
+#endif
+
+ /* Make boot-up look pretty */
+ pr_info("%d CPUs available, %d CPUs total\n", available_cpus,
+ total_cpus);
+
return 0;
}

@@ -221,6 +284,61 @@ static int __init acpi_parse_madt_gic_distributor_entries(void)
return 0;
}

+static int setup_possible_cpus __initdata = -1;
+static int __init _setup_possible_cpus(char *str)
+{
+ get_option(&str, &setup_possible_cpus);
+ return 0;
+}
+early_param("possible_cpus", _setup_possible_cpus);
+
+/*
+ * cpu_possible_mask should be static, it cannot change as cpu's
+ * are onlined, or offlined. The reason is per-cpu data-structures
+ * are allocated by some modules at init time, and dont expect to
+ * do this dynamically on cpu arrival/departure.
+ * cpu_present_mask on the other hand can change dynamically.
+ * In case when cpu_hotplug is not compiled, then we resort to current
+ * behaviour, which is cpu_possible == cpu_present.
+ * - Ashok Raj
+ *
+ * Three ways to find out the number of additional hotplug CPUs:
+ * - If the BIOS specified disabled CPUs in ACPI/mptables use that.
+ * - The user can overwrite it with possible_cpus=NUM
+ * - Otherwise don't reserve additional CPUs.
+ * We do this because additional CPUs waste a lot of memory.
+ * -AK
+ */
+void __init prefill_possible_map(void)
+{
+ int i;
+ int possible, disabled_cpus;
+
+ disabled_cpus = total_cpus - available_cpus;
+
+ if (setup_possible_cpus == -1) {
+ if (disabled_cpus > 0)
+ setup_possible_cpus = disabled_cpus;
+ else
+ setup_possible_cpus = 0;
+ }
+
+ possible = available_cpus + setup_possible_cpus;
+
+ pr_info("SMP: the system is limited to %d CPUs\n", nr_cpu_ids);
+
+ if (possible > nr_cpu_ids)
+ possible = nr_cpu_ids;
+
+ pr_info("SMP: Allowing %d CPUs, %d hotplug CPUs\n",
+ possible, max((possible - available_cpus), 0));
+
+ for (i = 0; i < possible; i++)
+ set_cpu_possible(i, true);
+ for (; i < NR_CPUS; i++)
+ set_cpu_possible(i, false);
+}
+
int acpi_gsi_to_irq(u32 gsi, unsigned int *irq)
{
*irq = gsi_to_irq(gsi);
--
1.7.9.5