[PATCH linux v2 2/9] x86/acpi: store ACPI ids from MADT for future usage

From: Vitaly Kuznetsov
Date: Thu Jun 30 2016 - 11:59:14 EST


Currently we don't save ACPI ids (unlike LAPIC ids which go to
x86_cpu_to_apicid) from MADT and we may need this information later.
Particularly, ACPI ids is the only existent way for a PVHVM Xen guest
to figure out Xen's idea of its vCPUs ids before these CPUs boot and
in some cases these ids diverge from Linux's cpu ids.

Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
arch/x86/include/asm/cpu.h | 1 +
arch/x86/include/asm/smp.h | 2 ++
arch/x86/kernel/acpi/boot.c | 16 ++++++++++++----
arch/x86/kernel/apic/apic.c | 2 ++
arch/x86/kernel/setup_percpu.c | 3 +++
5 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h
index 678637a..a7fb9dd 100644
--- a/arch/x86/include/asm/cpu.h
+++ b/arch/x86/include/asm/cpu.h
@@ -16,6 +16,7 @@ extern void prefill_possible_map(void);
static inline void prefill_possible_map(void) {}

#define cpu_physical_id(cpu) boot_cpu_physical_apicid
+#define cpu_acpi_id(cpu) 0
#define safe_smp_processor_id() 0
#define stack_smp_processor_id() 0

diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
index 66b0573..c47b42b 100644
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -33,6 +33,7 @@ static inline struct cpumask *cpu_llc_shared_mask(int cpu)
}

DECLARE_EARLY_PER_CPU_READ_MOSTLY(u16, x86_cpu_to_apicid);
+DECLARE_EARLY_PER_CPU_READ_MOSTLY(u32, x86_cpu_to_acpiid);
DECLARE_EARLY_PER_CPU_READ_MOSTLY(u16, x86_bios_cpu_apicid);
#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86_32)
DECLARE_EARLY_PER_CPU_READ_MOSTLY(int, x86_cpu_to_logical_apicid);
@@ -147,6 +148,7 @@ void x86_idle_thread_init(unsigned int cpu, struct task_struct *idle);
void smp_store_boot_cpu_info(void);
void smp_store_cpu_info(int id);
#define cpu_physical_id(cpu) per_cpu(x86_cpu_to_apicid, cpu)
+#define cpu_acpi_id(cpu) per_cpu(x86_cpu_to_acpiid, cpu)

#else /* !CONFIG_SMP */
#define wbinvd_on_cpu(cpu) wbinvd()
diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 9414f84..6738e5c 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -161,13 +161,15 @@ static int __init acpi_parse_madt(struct acpi_table_header *table)
/**
* acpi_register_lapic - register a local apic and generates a logic cpu number
* @id: local apic id to register
+ * @acpiid: ACPI id to register
* @enabled: this cpu is enabled or not
*
* Returns the logic cpu number which maps to the local apic
*/
-static int acpi_register_lapic(int id, u8 enabled)
+static int acpi_register_lapic(int id, u32 acpiid, u8 enabled)
{
unsigned int ver = 0;
+ int cpu;

if (id >= MAX_LOCAL_APIC) {
printk(KERN_INFO PREFIX "skipped apicid that is too big\n");
@@ -182,7 +184,11 @@ static int acpi_register_lapic(int id, u8 enabled)
if (boot_cpu_physical_apicid != -1U)
ver = apic_version[boot_cpu_physical_apicid];

- return generic_processor_info(id, ver);
+ cpu = generic_processor_info(id, ver);
+ if (cpu >= 0)
+ early_per_cpu(x86_cpu_to_acpiid, cpu) = acpiid;
+
+ return cpu;
}

static int __init
@@ -212,7 +218,7 @@ acpi_parse_x2apic(struct acpi_subtable_header *header, const unsigned long end)
if (!apic->apic_id_valid(apic_id) && enabled)
printk(KERN_WARNING PREFIX "x2apic entry ignored\n");
else
- acpi_register_lapic(apic_id, enabled);
+ acpi_register_lapic(apic_id, processor->uid, enabled);
#else
printk(KERN_WARNING PREFIX "x2apic entry ignored\n");
#endif
@@ -240,6 +246,7 @@ acpi_parse_lapic(struct acpi_subtable_header * header, const unsigned long end)
* when we use CPU hotplug.
*/
acpi_register_lapic(processor->id, /* APIC ID */
+ processor->processor_id, /* ACPI ID */
processor->lapic_flags & ACPI_MADT_ENABLED);

return 0;
@@ -258,6 +265,7 @@ acpi_parse_sapic(struct acpi_subtable_header *header, const unsigned long end)
acpi_table_print_madt_entry(header);

acpi_register_lapic((processor->id << 8) | processor->eid,/* APIC ID */
+ processor->processor_id, /* ACPI ID */
processor->lapic_flags & ACPI_MADT_ENABLED);

return 0;
@@ -714,7 +722,7 @@ int acpi_map_cpu(acpi_handle handle, phys_cpuid_t physid, int *pcpu)
{
int cpu;

- cpu = acpi_register_lapic(physid, ACPI_MADT_ENABLED);
+ cpu = acpi_register_lapic(physid, U32_MAX, ACPI_MADT_ENABLED);
if (cpu < 0) {
pr_info(PREFIX "Unable to map lapic to logical cpu number\n");
return cpu;
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 60078a6..db2326f 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -92,8 +92,10 @@ static int apic_extnmi = APIC_EXTNMI_BSP;
*/
DEFINE_EARLY_PER_CPU_READ_MOSTLY(u16, x86_cpu_to_apicid, BAD_APICID);
DEFINE_EARLY_PER_CPU_READ_MOSTLY(u16, x86_bios_cpu_apicid, BAD_APICID);
+DEFINE_EARLY_PER_CPU_READ_MOSTLY(u32, x86_cpu_to_acpiid, U32_MAX);
EXPORT_EARLY_PER_CPU_SYMBOL(x86_cpu_to_apicid);
EXPORT_EARLY_PER_CPU_SYMBOL(x86_bios_cpu_apicid);
+EXPORT_EARLY_PER_CPU_SYMBOL(x86_cpu_to_acpiid);

#ifdef CONFIG_X86_32

diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index e4fcb87..7a40e06 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -236,6 +236,8 @@ void __init setup_per_cpu_areas(void)
early_per_cpu_map(x86_cpu_to_apicid, cpu);
per_cpu(x86_bios_cpu_apicid, cpu) =
early_per_cpu_map(x86_bios_cpu_apicid, cpu);
+ per_cpu(x86_cpu_to_acpiid, cpu) =
+ early_per_cpu_map(x86_cpu_to_acpiid, cpu);
#endif
#ifdef CONFIG_X86_32
per_cpu(x86_cpu_to_logical_apicid, cpu) =
@@ -271,6 +273,7 @@ void __init setup_per_cpu_areas(void)
#ifdef CONFIG_X86_LOCAL_APIC
early_per_cpu_ptr(x86_cpu_to_apicid) = NULL;
early_per_cpu_ptr(x86_bios_cpu_apicid) = NULL;
+ early_per_cpu_ptr(x86_cpu_to_acpiid) = NULL;
#endif
#ifdef CONFIG_X86_32
early_per_cpu_ptr(x86_cpu_to_logical_apicid) = NULL;
--
2.5.5