* [PATCH v6 1/1] x86/acpi, x86/boot: Add multiprocessor wake-up support
@ 2021-06-01 14:21 Kuppuswamy Sathyanarayanan
2021-06-01 17:36 ` Rafael J. Wysocki
0 siblings, 1 reply; 3+ messages in thread
From: Kuppuswamy Sathyanarayanan @ 2021-06-01 14:21 UTC (permalink / raw)
To: Rafael J Wysocki, Thomas Gleixner, Ingo Molnar, H . Peter Anvin,
Peter Zijlstra
Cc: Len Brown, Kuppuswamy Sathyanarayanan, Sean Christopherson,
Andi Kleen, x86, linux-kernel, linux-acpi
As per ACPI specification r6.4, sec 5.2.12.19, a new sub
structure – multiprocessor wake-up structure - is added to the
ACPI Multiple APIC Description Table (MADT) to describe the
information of the mailbox. If a platform firmware produces the
multiprocessor wake-up structure, then OS may use this new
mailbox-based mechanism to wake up the APs.
Add ACPI MADT wake table parsing support for x86 platform and if
MADT wake table is present, update apic->wakeup_secondary_cpu with
new API which uses MADT wake mailbox to wake-up CPU.
Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
---
Changes since v5:
* None ( CCed ACPI list)
Changes since v4:
* Used smp_store_release() in place of WRITE_ONCE().
* Addressed some checkpatch warnings.
Changes since v3:
* Removed acpi_mp_wake_mailbox_init() and moved init code to
acpi_wakeup_cpu().
* Removed redundant NULL pointer check for acpi_mp_wake_mailbox.
* Added comments/debug prints as per Rafael's suggestion.
* Removed MADT/SVKL ACPI patches from this patchset. It will be
merged via ACPICA submission.
arch/x86/include/asm/apic.h | 3 ++
arch/x86/kernel/acpi/boot.c | 96 +++++++++++++++++++++++++++++++++++++
arch/x86/kernel/apic/apic.c | 8 ++++
3 files changed, 107 insertions(+)
diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 412b51e059c8..3e94e1f402ea 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -487,6 +487,9 @@ static inline unsigned int read_apic_id(void)
return apic->get_apic_id(reg);
}
+typedef int (*wakeup_cpu_handler)(int apicid, unsigned long start_eip);
+extern void acpi_wake_cpu_handler_update(wakeup_cpu_handler handler);
+
extern int default_apic_id_valid(u32 apicid);
extern int default_acpi_madt_oem_check(char *, char *);
extern void default_setup_apic_routing(void);
diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 14cd3186dc77..c51134eb55d0 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -65,6 +65,10 @@ int acpi_fix_pin2_polarity __initdata;
static u64 acpi_lapic_addr __initdata = APIC_DEFAULT_PHYS_BASE;
#endif
+static struct acpi_madt_multiproc_wakeup_mailbox *acpi_mp_wake_mailbox;
+static u64 acpi_mp_wake_mailbox_paddr;
+static physid_mask_t apic_id_wakemap = PHYSID_MASK_NONE;
+
#ifdef CONFIG_X86_IO_APIC
/*
* Locks related to IOAPIC hotplug
@@ -329,6 +333,68 @@ acpi_parse_lapic_nmi(union acpi_subtable_headers * header, const unsigned long e
return 0;
}
+static int acpi_wakeup_cpu(int apicid, unsigned long start_ip)
+{
+ u8 timeout = 0xFF;
+
+ /* Remap mailbox memory only for the first call to acpi_wakeup_cpu() */
+ if (physids_empty(apic_id_wakemap)) {
+ acpi_mp_wake_mailbox = memremap(acpi_mp_wake_mailbox_paddr,
+ sizeof(*acpi_mp_wake_mailbox),
+ MEMREMAP_WB);
+ }
+
+ /*
+ * According to the ACPI specification r6.4, sec 5.2.12.19, the
+ * mailbox-based wakeup mechanism cannot be used more than once
+ * for the same CPU, so skip sending wake commands to already
+ * awake CPU.
+ */
+ if (physid_isset(apicid, apic_id_wakemap)) {
+ pr_err("CPU already awake (APIC ID %x), skipping wakeup\n",
+ apicid);
+ return -EINVAL;
+ }
+
+ /*
+ * Mailbox memory is shared between firmware and OS. Firmware will
+ * listen on mailbox command address, and once it receives the wakeup
+ * command, CPU associated with the given apicid will be booted. So,
+ * the value of apic_id and wakeup_vector has to be set before updating
+ * the wakeup command. So use smp_store_release to let the compiler know
+ * about it and preserve the order of writes.
+ */
+ smp_store_release(&acpi_mp_wake_mailbox->apic_id, apicid);
+ smp_store_release(&acpi_mp_wake_mailbox->wakeup_vector, start_ip);
+ smp_store_release(&acpi_mp_wake_mailbox->command,
+ ACPI_MP_WAKE_COMMAND_WAKEUP);
+
+ /*
+ * After writing wakeup command, wait for maximum timeout of 0xFF
+ * for firmware to reset the command address back zero to indicate
+ * the successful reception of command.
+ * NOTE: 255 as timeout value is decided based on our experiments.
+ *
+ * XXX: Change the timeout once ACPI specification comes up with
+ * standard maximum timeout value.
+ */
+ while (READ_ONCE(acpi_mp_wake_mailbox->command) && timeout--)
+ cpu_relax();
+
+ if (timeout) {
+ /*
+ * If the CPU wakeup process is successful, store the
+ * status in apic_id_wakemap to prevent re-wakeup
+ * requests.
+ */
+ physid_set(apicid, apic_id_wakemap);
+ return 0;
+ }
+
+ /* If timed out (timeout == 0), return error */
+ return -EIO;
+}
+
#endif /*CONFIG_X86_LOCAL_APIC */
#ifdef CONFIG_X86_IO_APIC
@@ -1086,6 +1152,30 @@ static int __init acpi_parse_madt_lapic_entries(void)
}
return 0;
}
+
+static int __init acpi_parse_mp_wake(union acpi_subtable_headers *header,
+ const unsigned long end)
+{
+ struct acpi_madt_multiproc_wakeup *mp_wake;
+
+ if (acpi_mp_wake_mailbox)
+ return -EINVAL;
+
+ if (!IS_ENABLED(CONFIG_SMP))
+ return -ENODEV;
+
+ mp_wake = (struct acpi_madt_multiproc_wakeup *)header;
+ if (BAD_MADT_ENTRY(mp_wake, end))
+ return -EINVAL;
+
+ acpi_table_print_madt_entry(&header->common);
+
+ acpi_mp_wake_mailbox_paddr = mp_wake->base_address;
+
+ acpi_wake_cpu_handler_update(acpi_wakeup_cpu);
+
+ return 0;
+}
#endif /* CONFIG_X86_LOCAL_APIC */
#ifdef CONFIG_X86_IO_APIC
@@ -1284,6 +1374,12 @@ static void __init acpi_process_madt(void)
smp_found_config = 1;
}
+
+ /*
+ * Parse MADT MP Wake entry.
+ */
+ acpi_table_parse_madt(ACPI_MADT_TYPE_MULTIPROC_WAKEUP,
+ acpi_parse_mp_wake, 1);
}
if (error == -EINVAL) {
/*
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 4f26700f314d..f1b90a4b89e8 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -2554,6 +2554,14 @@ u32 x86_msi_msg_get_destid(struct msi_msg *msg, bool extid)
}
EXPORT_SYMBOL_GPL(x86_msi_msg_get_destid);
+void __init acpi_wake_cpu_handler_update(wakeup_cpu_handler handler)
+{
+ struct apic **drv;
+
+ for (drv = __apicdrivers; drv < __apicdrivers_end; drv++)
+ (*drv)->wakeup_secondary_cpu = handler;
+}
+
/*
* Override the generic EOI implementation with an optimized version.
* Only called during early boot when only one CPU is active and with
--
2.25.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v6 1/1] x86/acpi, x86/boot: Add multiprocessor wake-up support
2021-06-01 14:21 [PATCH v6 1/1] x86/acpi, x86/boot: Add multiprocessor wake-up support Kuppuswamy Sathyanarayanan
@ 2021-06-01 17:36 ` Rafael J. Wysocki
2021-06-08 23:19 ` Kuppuswamy, Sathyanarayanan
0 siblings, 1 reply; 3+ messages in thread
From: Rafael J. Wysocki @ 2021-06-01 17:36 UTC (permalink / raw)
To: Kuppuswamy Sathyanarayanan
Cc: Rafael J Wysocki, Thomas Gleixner, Ingo Molnar, H . Peter Anvin,
Peter Zijlstra, Len Brown, Kuppuswamy Sathyanarayanan,
Sean Christopherson, Andi Kleen, the arch/x86 maintainers,
Linux Kernel Mailing List, ACPI Devel Maling List
On Tue, Jun 1, 2021 at 4:21 PM Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@linux.intel.com> wrote:
>
> As per ACPI specification r6.4, sec 5.2.12.19, a new sub
> structure – multiprocessor wake-up structure - is added to the
> ACPI Multiple APIC Description Table (MADT) to describe the
> information of the mailbox. If a platform firmware produces the
> multiprocessor wake-up structure, then OS may use this new
> mailbox-based mechanism to wake up the APs.
>
> Add ACPI MADT wake table parsing support for x86 platform and if
> MADT wake table is present, update apic->wakeup_secondary_cpu with
> new API which uses MADT wake mailbox to wake-up CPU.
>
> Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
> Reviewed-by: Andi Kleen <ak@linux.intel.com>
All of my comments have been addressed, so
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
>
> Changes since v5:
> * None ( CCed ACPI list)
>
> Changes since v4:
> * Used smp_store_release() in place of WRITE_ONCE().
> * Addressed some checkpatch warnings.
>
> Changes since v3:
> * Removed acpi_mp_wake_mailbox_init() and moved init code to
> acpi_wakeup_cpu().
> * Removed redundant NULL pointer check for acpi_mp_wake_mailbox.
> * Added comments/debug prints as per Rafael's suggestion.
> * Removed MADT/SVKL ACPI patches from this patchset. It will be
> merged via ACPICA submission.
>
> arch/x86/include/asm/apic.h | 3 ++
> arch/x86/kernel/acpi/boot.c | 96 +++++++++++++++++++++++++++++++++++++
> arch/x86/kernel/apic/apic.c | 8 ++++
> 3 files changed, 107 insertions(+)
>
> diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
> index 412b51e059c8..3e94e1f402ea 100644
> --- a/arch/x86/include/asm/apic.h
> +++ b/arch/x86/include/asm/apic.h
> @@ -487,6 +487,9 @@ static inline unsigned int read_apic_id(void)
> return apic->get_apic_id(reg);
> }
>
> +typedef int (*wakeup_cpu_handler)(int apicid, unsigned long start_eip);
> +extern void acpi_wake_cpu_handler_update(wakeup_cpu_handler handler);
> +
> extern int default_apic_id_valid(u32 apicid);
> extern int default_acpi_madt_oem_check(char *, char *);
> extern void default_setup_apic_routing(void);
> diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
> index 14cd3186dc77..c51134eb55d0 100644
> --- a/arch/x86/kernel/acpi/boot.c
> +++ b/arch/x86/kernel/acpi/boot.c
> @@ -65,6 +65,10 @@ int acpi_fix_pin2_polarity __initdata;
> static u64 acpi_lapic_addr __initdata = APIC_DEFAULT_PHYS_BASE;
> #endif
>
> +static struct acpi_madt_multiproc_wakeup_mailbox *acpi_mp_wake_mailbox;
> +static u64 acpi_mp_wake_mailbox_paddr;
> +static physid_mask_t apic_id_wakemap = PHYSID_MASK_NONE;
> +
> #ifdef CONFIG_X86_IO_APIC
> /*
> * Locks related to IOAPIC hotplug
> @@ -329,6 +333,68 @@ acpi_parse_lapic_nmi(union acpi_subtable_headers * header, const unsigned long e
> return 0;
> }
>
> +static int acpi_wakeup_cpu(int apicid, unsigned long start_ip)
> +{
> + u8 timeout = 0xFF;
> +
> + /* Remap mailbox memory only for the first call to acpi_wakeup_cpu() */
> + if (physids_empty(apic_id_wakemap)) {
> + acpi_mp_wake_mailbox = memremap(acpi_mp_wake_mailbox_paddr,
> + sizeof(*acpi_mp_wake_mailbox),
> + MEMREMAP_WB);
> + }
> +
> + /*
> + * According to the ACPI specification r6.4, sec 5.2.12.19, the
> + * mailbox-based wakeup mechanism cannot be used more than once
> + * for the same CPU, so skip sending wake commands to already
> + * awake CPU.
> + */
> + if (physid_isset(apicid, apic_id_wakemap)) {
> + pr_err("CPU already awake (APIC ID %x), skipping wakeup\n",
> + apicid);
> + return -EINVAL;
> + }
> +
> + /*
> + * Mailbox memory is shared between firmware and OS. Firmware will
> + * listen on mailbox command address, and once it receives the wakeup
> + * command, CPU associated with the given apicid will be booted. So,
> + * the value of apic_id and wakeup_vector has to be set before updating
> + * the wakeup command. So use smp_store_release to let the compiler know
> + * about it and preserve the order of writes.
> + */
> + smp_store_release(&acpi_mp_wake_mailbox->apic_id, apicid);
> + smp_store_release(&acpi_mp_wake_mailbox->wakeup_vector, start_ip);
> + smp_store_release(&acpi_mp_wake_mailbox->command,
> + ACPI_MP_WAKE_COMMAND_WAKEUP);
> +
> + /*
> + * After writing wakeup command, wait for maximum timeout of 0xFF
> + * for firmware to reset the command address back zero to indicate
> + * the successful reception of command.
> + * NOTE: 255 as timeout value is decided based on our experiments.
> + *
> + * XXX: Change the timeout once ACPI specification comes up with
> + * standard maximum timeout value.
> + */
> + while (READ_ONCE(acpi_mp_wake_mailbox->command) && timeout--)
> + cpu_relax();
> +
> + if (timeout) {
> + /*
> + * If the CPU wakeup process is successful, store the
> + * status in apic_id_wakemap to prevent re-wakeup
> + * requests.
> + */
> + physid_set(apicid, apic_id_wakemap);
> + return 0;
> + }
> +
> + /* If timed out (timeout == 0), return error */
> + return -EIO;
> +}
> +
> #endif /*CONFIG_X86_LOCAL_APIC */
>
> #ifdef CONFIG_X86_IO_APIC
> @@ -1086,6 +1152,30 @@ static int __init acpi_parse_madt_lapic_entries(void)
> }
> return 0;
> }
> +
> +static int __init acpi_parse_mp_wake(union acpi_subtable_headers *header,
> + const unsigned long end)
> +{
> + struct acpi_madt_multiproc_wakeup *mp_wake;
> +
> + if (acpi_mp_wake_mailbox)
> + return -EINVAL;
> +
> + if (!IS_ENABLED(CONFIG_SMP))
> + return -ENODEV;
> +
> + mp_wake = (struct acpi_madt_multiproc_wakeup *)header;
> + if (BAD_MADT_ENTRY(mp_wake, end))
> + return -EINVAL;
> +
> + acpi_table_print_madt_entry(&header->common);
> +
> + acpi_mp_wake_mailbox_paddr = mp_wake->base_address;
> +
> + acpi_wake_cpu_handler_update(acpi_wakeup_cpu);
> +
> + return 0;
> +}
> #endif /* CONFIG_X86_LOCAL_APIC */
>
> #ifdef CONFIG_X86_IO_APIC
> @@ -1284,6 +1374,12 @@ static void __init acpi_process_madt(void)
>
> smp_found_config = 1;
> }
> +
> + /*
> + * Parse MADT MP Wake entry.
> + */
> + acpi_table_parse_madt(ACPI_MADT_TYPE_MULTIPROC_WAKEUP,
> + acpi_parse_mp_wake, 1);
> }
> if (error == -EINVAL) {
> /*
> diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
> index 4f26700f314d..f1b90a4b89e8 100644
> --- a/arch/x86/kernel/apic/apic.c
> +++ b/arch/x86/kernel/apic/apic.c
> @@ -2554,6 +2554,14 @@ u32 x86_msi_msg_get_destid(struct msi_msg *msg, bool extid)
> }
> EXPORT_SYMBOL_GPL(x86_msi_msg_get_destid);
>
> +void __init acpi_wake_cpu_handler_update(wakeup_cpu_handler handler)
> +{
> + struct apic **drv;
> +
> + for (drv = __apicdrivers; drv < __apicdrivers_end; drv++)
> + (*drv)->wakeup_secondary_cpu = handler;
> +}
> +
> /*
> * Override the generic EOI implementation with an optimized version.
> * Only called during early boot when only one CPU is active and with
> --
> 2.25.1
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v6 1/1] x86/acpi, x86/boot: Add multiprocessor wake-up support
2021-06-01 17:36 ` Rafael J. Wysocki
@ 2021-06-08 23:19 ` Kuppuswamy, Sathyanarayanan
0 siblings, 0 replies; 3+ messages in thread
From: Kuppuswamy, Sathyanarayanan @ 2021-06-08 23:19 UTC (permalink / raw)
To: Rafael J. Wysocki, Thomas Gleixner, Peter Zijlstra
Cc: Rafael J Wysocki, Ingo Molnar, H . Peter Anvin, Len Brown,
Kuppuswamy Sathyanarayanan, Sean Christopherson, Andi Kleen,
the arch/x86 maintainers, Linux Kernel Mailing List,
ACPI Devel Maling List
On 6/1/21 10:36 AM, Rafael J. Wysocki wrote:
>> As per ACPI specification r6.4, sec 5.2.12.19, a new sub
>> structure – multiprocessor wake-up structure - is added to the
>> ACPI Multiple APIC Description Table (MADT) to describe the
>> information of the mailbox. If a platform firmware produces the
>> multiprocessor wake-up structure, then OS may use this new
>> mailbox-based mechanism to wake up the APs.
>>
>> Add ACPI MADT wake table parsing support for x86 platform and if
>> MADT wake table is present, update apic->wakeup_secondary_cpu with
>> new API which uses MADT wake mailbox to wake-up CPU.
>>
>> Co-developed-by: Sean Christopherson<sean.j.christopherson@intel.com>
>> Signed-off-by: Sean Christopherson<sean.j.christopherson@intel.com>
>> Signed-off-by: Kuppuswamy Sathyanarayanan<sathyanarayanan.kuppuswamy@linux.intel.com>
>> Reviewed-by: Andi Kleen<ak@linux.intel.com>
> All of my comments have been addressed, so
>
> Reviewed-by: Rafael J. Wysocki<rafael.j.wysocki@intel.com>
Thomas/Peter Z,
Gentle ping. Any comments?
>
--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-06-08 23:19 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-06-01 14:21 [PATCH v6 1/1] x86/acpi, x86/boot: Add multiprocessor wake-up support Kuppuswamy Sathyanarayanan
2021-06-01 17:36 ` Rafael J. Wysocki
2021-06-08 23:19 ` Kuppuswamy, Sathyanarayanan
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).