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Date: Wed, 26 Aug 2015 14:56:50 +0200
From: Tomasz Nowicki <tomasz.nowicki@...aro.org>
To: Lukasz Anaczkowski <lukasz.anaczkowski@...el.com>,
tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
x86@...nel.org, jason@...edaemon.net
CC: rjw@...ysocki.net, len.brown@...el.com, pavel@....cz,
linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-acpi@...r.kernel.org, Yinghai Lu <yinghai@...nel.org>
Subject: Re: [PATCH] x86, acpi: Handle lapic/x2apic entries in MADT
On 03.08.2015 20:26, Lukasz Anaczkowski wrote:
> v2: Fixed ARM64 syntax error
>
> From the ACPI spec:
> "Logical processors with APIC ID values less than 0xFF
> (whether in XAPIC or X2APIC mode) must use the Processor LAPIC
> structure [...]. Logical processors with APIC ID values 0xFF and
> greater must use the Processor Local x2APIC structure."
>
> Because of above, BIOS is first enumerating cores with HT with
> LAPIC values (<0xFF) and then rest with X2APIC values (>=0xFF).
>
> With current kernel code, where enumeration is in order:
> BSP, X2APIC, LAPIC
> enumeration on machine with more than 255 CPUs (each core with 4 HT)
> first X2APIC IDs get low logical CPU IDs (1..x) and then LAPIC IDs
> get higher logical CPU IDs (50..y), as in example below:
>
> Core LCpu ApicId LCpu ApicId LCpu ApicId LCpu ApicId
> 0 0 0000 97 0001 145 0002 193 0003
> 1 50 0004 98 0005 146 0006 194 0007
> 2 51 0010 99 0011 147 0012 195 0013
> 3 52 0014 100 0015 148 0016 196 0017
> 4 53 0018 101 0019 149 001a 197 001b
> 5 54 001c 102 001d 150 001e 198 001f
> ...
> 62 95 00f8 143 00f9 191 00fa 239 00fb
> 63 37 00ff 96 00fc 144 00fd 192 00fe
> 64 1 0100 13 0101 25 0102 38 0103
> 65 2 0104 14 0105 26 0106 39 0107
> ...
>
> (Core - physical core, LCpu - logical CPU, ApicId - ID assigned
> by BIOS).
>
> This is wrong for the following reasons:
> () it's hard to predict how cores and threads will be enumerated
> () when it's hard to predict, s/w threads cannot be properly affinitized
> causing significant performance impact due to e.g. inproper cache
> sharing
> () enumeration is inconsistent with how threads are enumerated on
> other Intel Xeon processors
>
> To fix this, each LAPIC/X2APIC entry from MADT table needs to be
> handled at the same time when processing it, thus adding
> acpi_subtable_proc structure which stores
> () ACPI table id
> () handler that processes table
> () counter how many items has been processed
> and passing it to acpi_table_parse_entries().
>
> Also, order in which MADT LAPIC/X2APIC handlers are passed is
> reversed to achieve correct CPU enumeration.
>
> In scenario when someone boots kernel with options 'maxcpus=72 nox2apic',
> in result less cores may be booted, since some of the CPUs the kernel
> will try to use will have APIC ID >= 0xFF. In such case, one
> should not pass 'nox2apic'.
>
> Disclimer: code parsing MADT LAPIC/X2APIC has not been touched since 2009,
> when X2APIC support was initially added. I do not know why MADT parsing
> code was added in the reversed order in the first place.
> I guess it didn't matter at that time since nobody cared about cores
> with APIC IDs >= 0xFF, right?
>
> This patch is based on work of "Yinghai Lu <yinghai@...nel.org>"
> previously published at https://lkml.org/lkml/2013/1/21/563,
> thus putting Yinghai Lu as 'Signed-off-by', as well.
>
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> Signed-off-by: Lukasz Anaczkowski <lukasz.anaczkowski@...el.com>
> ---
> arch/x86/kernel/acpi/boot.c | 29 +++++++++++++-----
> drivers/acpi/numa.c | 28 ++++++++++++-----
> drivers/acpi/tables.c | 75 ++++++++++++++++++++++++++++-----------------
> drivers/irqchip/irq-gic.c | 15 ++++++---
> include/linux/acpi.h | 13 ++++++--
> 5 files changed, 111 insertions(+), 49 deletions(-)
>
> diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
> index e49ee24..fb4a9d6 100644
> --- a/arch/x86/kernel/acpi/boot.c
> +++ b/arch/x86/kernel/acpi/boot.c
> @@ -981,6 +981,7 @@ static int __init acpi_parse_madt_lapic_entries(void)
> {
> int count;
> int x2count = 0;
> + struct acpi_subtable_proc madt_proc[2];
>
> if (!cpu_has_apic)
> return -ENODEV;
> @@ -1004,10 +1005,16 @@ static int __init acpi_parse_madt_lapic_entries(void)
> acpi_parse_sapic, MAX_LOCAL_APIC);
>
> if (!count) {
> - x2count = acpi_table_parse_madt(ACPI_MADT_TYPE_LOCAL_X2APIC,
> - acpi_parse_x2apic, MAX_LOCAL_APIC);
> - count = acpi_table_parse_madt(ACPI_MADT_TYPE_LOCAL_APIC,
> - acpi_parse_lapic, MAX_LOCAL_APIC);
> + memset(madt_proc, 0, sizeof(madt_proc));
> + madt_proc[0].id = ACPI_MADT_TYPE_LOCAL_APIC;
> + madt_proc[0].handler = acpi_parse_lapic;
> + madt_proc[1].id = ACPI_MADT_TYPE_LOCAL_X2APIC;
> + madt_proc[1].handler = acpi_parse_x2apic;
> + acpi_table_parse_entries_array(ACPI_SIG_MADT,
> + sizeof(struct acpi_table_madt),
> + madt_proc, ARRAY_SIZE(madt_proc), MAX_LOCAL_APIC);
> + count = madt_proc[0].count;
> + x2count = madt_proc[1].count;
> }
> if (!count && !x2count) {
> printk(KERN_ERR PREFIX "No LAPIC entries present\n");
> @@ -1019,10 +1026,16 @@ static int __init acpi_parse_madt_lapic_entries(void)
> return count;
> }
>
> - x2count = acpi_table_parse_madt(ACPI_MADT_TYPE_LOCAL_X2APIC_NMI,
> - acpi_parse_x2apic_nmi, 0);
> - count = acpi_table_parse_madt(ACPI_MADT_TYPE_LOCAL_APIC_NMI,
> - acpi_parse_lapic_nmi, 0);
> + memset(madt_proc, 0, sizeof(madt_proc));
> + madt_proc[0].id = ACPI_MADT_TYPE_LOCAL_X2APIC_NMI;
> + madt_proc[0].handler = acpi_parse_x2apic_nmi;
> + madt_proc[1].id = ACPI_MADT_TYPE_LOCAL_APIC_NMI;
> + madt_proc[1].handler = acpi_parse_lapic_nmi;
> + acpi_table_parse_entries_array(ACPI_SIG_MADT,
> + sizeof(struct acpi_table_madt),
> + madt_proc, ARRAY_SIZE(madt_proc), 0);
> + count = madt_proc[0].count;
> + x2count = madt_proc[1].count;
> if (count < 0 || x2count < 0) {
> printk(KERN_ERR PREFIX "Error parsing LAPIC NMI entry\n");
> /* TBD: Cleanup to allow fallback to MPS */
> diff --git a/drivers/acpi/numa.c b/drivers/acpi/numa.c
> index acaa3b4..a000195 100644
> --- a/drivers/acpi/numa.c
> +++ b/drivers/acpi/numa.c
> @@ -314,9 +314,15 @@ static int __init
> acpi_table_parse_srat(enum acpi_srat_type id,
> acpi_tbl_entry_handler handler, unsigned int max_entries)
> {
> - return acpi_table_parse_entries(ACPI_SIG_SRAT,
> - sizeof(struct acpi_table_srat), id,
> - handler, max_entries);
> + struct acpi_subtable_proc srat_proc;
> +
> + memset(&srat_proc, 0, sizeof(srat_proc));
> + srat_proc.id = id;
> + srat_proc.handler = handler;
> +
> + return acpi_table_parse_entries_array(ACPI_SIG_SRAT,
> + sizeof(struct acpi_table_srat),
> + &srat_proc, 1, max_entries);
> }
>
> int __init acpi_numa_init(void)
> @@ -331,10 +337,18 @@ int __init acpi_numa_init(void)
>
> /* SRAT: Static Resource Affinity Table */
> if (!acpi_table_parse(ACPI_SIG_SRAT, acpi_parse_srat)) {
> - acpi_table_parse_srat(ACPI_SRAT_TYPE_X2APIC_CPU_AFFINITY,
> - acpi_parse_x2apic_affinity, 0);
> - acpi_table_parse_srat(ACPI_SRAT_TYPE_CPU_AFFINITY,
> - acpi_parse_processor_affinity, 0);
> + struct acpi_subtable_proc srat_proc[2];
> +
> + memset(srat_proc, 0, sizeof(srat_proc));
> + srat_proc[0].id = ACPI_SRAT_TYPE_X2APIC_CPU_AFFINITY;
> + srat_proc[0].handler = acpi_parse_x2apic_affinity;
> + srat_proc[1].id = ACPI_SRAT_TYPE_CPU_AFFINITY;
> + srat_proc[1].handler = acpi_parse_processor_affinity;
> +
> + acpi_table_parse_entries_array(ACPI_SIG_SRAT,
> + sizeof(struct acpi_table_srat),
> + srat_proc, ARRAY_SIZE(srat_proc), 0);
> +
> cnt = acpi_table_parse_srat(ACPI_SRAT_TYPE_MEMORY_AFFINITY,
> acpi_parse_memory_affinity,
> NR_NODE_MEMBLKS);
> diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
> index 2e19189..1217e41 100644
> --- a/drivers/acpi/tables.c
> +++ b/drivers/acpi/tables.c
> @@ -216,25 +216,27 @@ void acpi_table_print_madt_entry(struct acpi_subtable_header *header)
>
> int __init
> acpi_parse_entries(char *id, unsigned long table_size,
> - acpi_tbl_entry_handler handler,
> struct acpi_table_header *table_header,
> - int entry_id, unsigned int max_entries)
> + struct acpi_subtable_proc *proc, int proc_num,
> + unsigned int max_entries)
> {
> struct acpi_subtable_header *entry;
> int count = 0;
> unsigned long table_end;
> + int i;
>
> - if (acpi_disabled)
> + if (acpi_disabled) {
> + proc[0].count = -ENODEV;
> return -ENODEV;
> -
> - if (!id || !handler)
> - return -EINVAL;
> -
> - if (!table_size)
> + }
> + if (!table_size) {
> + proc[0].count = -EINVAL;
> return -EINVAL;
> + }
>
> if (!table_header) {
> pr_warn("%4.4s not present\n", id);
> + proc[0].count = -ENODEV;
> return -ENODEV;
> }
>
> @@ -247,12 +249,17 @@ acpi_parse_entries(char *id, unsigned long table_size,
>
> while (((unsigned long)entry) + sizeof(struct acpi_subtable_header) <
> table_end) {
> - if (entry->type == entry_id
> - && (!max_entries || count < max_entries)) {
> - if (handler(entry, table_end))
> + for (i = 0; i < proc_num; i++) {
> + if (entry->type != proc[i].id)
> + continue;
> + if (max_entries && count++ >= max_entries)
> + continue;
> + if (proc[i].handler(entry, table_end)) {
> + proc[i].count = -EINVAL;
> return -EINVAL;
> -
> - count++;
> + }
> + proc[i].count++;
> + break;
> }
>
> /*
> @@ -260,7 +267,11 @@ acpi_parse_entries(char *id, unsigned long table_size,
> * infinite loop.
> */
> if (entry->length == 0) {
> - pr_err("[%4.4s:0x%02x] Invalid zero length\n", id, entry_id);
> + pr_err("[%4.4s:0x%02x ", id, proc[0].id);
> + for (i = 1; i < proc_num; i++)
> + pr_cont(" 0x%02x", proc[i].id);
> + pr_cont("] Invalid zero length\n");
> + proc[0].count = -EINVAL;
> return -EINVAL;
> }
>
> @@ -269,18 +280,20 @@ acpi_parse_entries(char *id, unsigned long table_size,
> }
>
> if (max_entries && count > max_entries) {
> - pr_warn("[%4.4s:0x%02x] ignored %i entries of %i found\n",
> - id, entry_id, count - max_entries, count);
> + pr_warn("[%4.4s:0x%02x ", id, proc[0].id);
> + for (i = 1; i < proc_num; i++)
> + pr_cont(" 0x%02x", proc[i].id);
> + pr_cont("] ignored %i entries of %i found\n",
> + count-max_entries, count);
> }
>
> return count;
> }
>
> int __init
> -acpi_table_parse_entries(char *id,
> +acpi_table_parse_entries_array(char *id,
> unsigned long table_size,
> - int entry_id,
> - acpi_tbl_entry_handler handler,
> + struct acpi_subtable_proc *proc, int proc_num,
> unsigned int max_entries)
> {
> struct acpi_table_header *table_header = NULL;
> @@ -288,11 +301,10 @@ acpi_table_parse_entries(char *id,
> int count;
> u32 instance = 0;
>
> - if (acpi_disabled)
> + if (acpi_disabled) {
> + proc[0].count = -ENODEV;
> return -ENODEV;
> -
> - if (!id || !handler)
> - return -EINVAL;
> + }
>
> if (!strncmp(id, ACPI_SIG_MADT, 4))
> instance = acpi_apic_instance;
> @@ -300,11 +312,12 @@ acpi_table_parse_entries(char *id,
> acpi_get_table_with_size(id, instance, &table_header, &tbl_size);
> if (!table_header) {
> pr_warn("%4.4s not present\n", id);
> + proc[0].count = -ENODEV;
> return -ENODEV;
> }
>
> - count = acpi_parse_entries(id, table_size, handler, table_header,
> - entry_id, max_entries);
> + count = acpi_parse_entries(id, table_size, table_header,
> + proc, proc_num, max_entries);
>
> early_acpi_os_unmap_memory((char *)table_header, tbl_size);
> return count;
> @@ -314,9 +327,15 @@ int __init
> acpi_table_parse_madt(enum acpi_madt_type id,
> acpi_tbl_entry_handler handler, unsigned int max_entries)
> {
> - return acpi_table_parse_entries(ACPI_SIG_MADT,
> - sizeof(struct acpi_table_madt), id,
> - handler, max_entries);
> + struct acpi_subtable_proc madt_proc;
> +
> + memset(&madt_proc, 0, sizeof(madt_proc));
> + madt_proc.id = id;
> + madt_proc.handler = handler;
> +
> + return acpi_table_parse_entries_array(ACPI_SIG_MADT,
> + sizeof(struct acpi_table_madt),
> + &madt_proc, 1, max_entries);
> }
>
> /**
> diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
> index 4dd8826..d98b866 100644
> --- a/drivers/irqchip/irq-gic.c
> +++ b/drivers/irqchip/irq-gic.c
> @@ -1091,12 +1091,16 @@ gic_v2_acpi_init(struct acpi_table_header *table)
> {
> void __iomem *cpu_base, *dist_base;
> int count;
> + struct acpi_subtable_proc gic_proc;
> +
> + memset(&gic_proc, 0, sizeof(gic_proc));
> + gic_proc.id = ACPI_MADT_TYPE_GENERIC_INTERRUPT;
> + gic_proc.handler = gic_acpi_parse_madt_cpu;
>
> /* Collect CPU base addresses */
> count = acpi_parse_entries(ACPI_SIG_MADT,
> sizeof(struct acpi_table_madt),
> - gic_acpi_parse_madt_cpu, table,
> - ACPI_MADT_TYPE_GENERIC_INTERRUPT, 0);
> + table, &gic_proc, 1, 0);
> if (count <= 0) {
> pr_err("No valid GICC entries exist\n");
> return -EINVAL;
> @@ -1106,10 +1110,13 @@ gic_v2_acpi_init(struct acpi_table_header *table)
> * Find distributor base address. We expect one distributor entry since
> * ACPI 5.1 spec neither support multi-GIC instances nor GIC cascade.
> */
> + memset(&gic_proc, 0, sizeof(gic_proc));
> + gic_proc.id = ACPI_MADT_TYPE_GENERIC_DISTRIBUTOR;
> + gic_proc.handler = gic_acpi_parse_madt_distributor;
> +
> count = acpi_parse_entries(ACPI_SIG_MADT,
> sizeof(struct acpi_table_madt),
> - gic_acpi_parse_madt_distributor, table,
> - ACPI_MADT_TYPE_GENERIC_DISTRIBUTOR, 0);
> + table, &gic_proc, 1, 0);
> if (count <= 0) {
> pr_err("No valid GICD entries exist\n");
> return -EINVAL;
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index d2445fa..59b17e8 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -135,6 +135,12 @@ static inline void acpi_initrd_override(void *data, size_t size)
> (!entry) || (unsigned long)entry + sizeof(*entry) > end || \
> ((struct acpi_subtable_header *)entry)->length < sizeof(*entry))
>
> +struct acpi_subtable_proc {
> + int id;
> + acpi_tbl_entry_handler handler;
> + int count;
> +};
> +
> char * __acpi_map_table (unsigned long phys_addr, unsigned long size);
> void __acpi_unmap_table(char *map, unsigned long size);
> int early_acpi_boot_init(void);
> @@ -145,10 +151,13 @@ int acpi_numa_init (void);
>
> int acpi_table_init (void);
> int acpi_table_parse(char *id, acpi_tbl_table_handler handler);
> +int acpi_table_parse_entries_array(char *id, unsigned long table_size,
> + struct acpi_subtable_proc *proc, int proc_num,
> + unsigned int max_entries);
> int __init acpi_parse_entries(char *id, unsigned long table_size,
> - acpi_tbl_entry_handler handler,
> struct acpi_table_header *table_header,
> - int entry_id, unsigned int max_entries);
> + struct acpi_subtable_proc *proc, int proc_num,
> + unsigned int max_entries);
> int __init acpi_table_parse_entries(char *id, unsigned long table_size,
> int entry_id,
> acpi_tbl_entry_handler handler,
>
You rename acpi_table_parse_entries -> acpi_table_parse_entries_array,
should acpi_table_parse_entries suppose to be removed above?
Tomasz
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