diff mbox series

[3/3] x86/acpi, x86/boot: Add multiprocessor wake-up support

Message ID 20210422192442.706906-4-sathyanarayanan.kuppuswamy@linux.intel.com (mailing list archive)
State Superseded, archived
Headers show
Series Add multiprocessor wake-up support | expand

Commit Message

Kuppuswamy Sathyanarayanan April 22, 2021, 7:24 p.m. UTC 
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>
---
 arch/x86/include/asm/apic.h     |  3 ++
 arch/x86/kernel/acpi/boot.c     | 56 +++++++++++++++++++++++++++++++++
 arch/x86/kernel/apic/probe_32.c |  8 +++++
 arch/x86/kernel/apic/probe_64.c |  8 +++++
 4 files changed, 75 insertions(+)

Comments

Thomas Gleixner April 22, 2021, 11:04 p.m. UTC | #1 
Kuppuswamy!

On Thu, Apr 22 2021 at 12:24, Kuppuswamy Sathyanarayanan wrote:
> +static int acpi_wakeup_cpu(int apicid, unsigned long start_ip)
> +{
> +	acpi_mp_wake_mailbox_init();
> +
> +	if (!acpi_mp_wake_mailbox)
> +		return -EINVAL;
> +
> +	WRITE_ONCE(acpi_mp_wake_mailbox->apic_id, apicid);
> +	WRITE_ONCE(acpi_mp_wake_mailbox->wakeup_vector, start_ip);
> +	WRITE_ONCE(acpi_mp_wake_mailbox->command, ACPI_MP_WAKE_COMMAND_WAKEUP);

What's the point of using WRITE_ONCE() here? Where is the required
READ_ONCE() counterpart and the required documentation in form of a
comment?

> +static int __init acpi_parse_mp_wake(union acpi_subtable_headers *header,
> +				      const unsigned long end)
> +{
...
> +	acpi_wake_cpu_handler_update(acpi_wakeup_cpu);
...

> +++ b/arch/x86/kernel/apic/probe_32.c
> @@ -207,3 +207,11 @@ int __init default_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
>  	}
>  	return 0;
>  }
> +
> +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;
> +}
> diff --git a/arch/x86/kernel/apic/probe_64.c b/arch/x86/kernel/apic/probe_64.c
> index c46720f185c0..986dbb68d3c4 100644
> --- a/arch/x86/kernel/apic/probe_64.c
> +++ b/arch/x86/kernel/apic/probe_64.c
> @@ -50,3 +50,11 @@ int __init default_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
>  	}
>  	return 0;
>  }
> +
> +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;
> +}

What's the reason for having two verbatim copies of the same function
which has no dependency on CONFIG_*_32/64 at all?

Thanks,

        tglx
Kuppuswamy Sathyanarayanan April 22, 2021, 11:39 p.m. UTC | #2 
On 4/22/21 4:04 PM, Thomas Gleixner wrote:
> Kuppuswamy!
> 
> On Thu, Apr 22 2021 at 12:24, Kuppuswamy Sathyanarayanan wrote:
>> +static int acpi_wakeup_cpu(int apicid, unsigned long start_ip)
>> +{
>> +	acpi_mp_wake_mailbox_init();
>> +
>> +	if (!acpi_mp_wake_mailbox)
>> +		return -EINVAL;
>> +
>> +	WRITE_ONCE(acpi_mp_wake_mailbox->apic_id, apicid);
>> +	WRITE_ONCE(acpi_mp_wake_mailbox->wakeup_vector, start_ip);
>> +	WRITE_ONCE(acpi_mp_wake_mailbox->command, ACPI_MP_WAKE_COMMAND_WAKEUP);
> 
> What's the point of using WRITE_ONCE() here? Where is the required
> READ_ONCE() counterpart and the required documentation in form of a
> comment?

mailbox memory is shared between firmware and OS. We use WRITE_ONCE to notify
compiler about it, and also to preserve the order of writes to these
addresses. As per MADT Wake protocol, once OS update the mailbox command
address with ACPI_MP_*_WAKEUP command, firmware will be bring the AP out sleep
state and trigger the boot process.
Since its a one way communication, we don't need to read the mailbox address
again. So there is no corresponding READ_ONCE() call.

I will add some comments about it in next version.

> 
>> +static int __init acpi_parse_mp_wake(union acpi_subtable_headers *header,
>> +				      const unsigned long end)
>> +{
> ...
>> +	acpi_wake_cpu_handler_update(acpi_wakeup_cpu);
> ...
> 
>> +++ b/arch/x86/kernel/apic/probe_32.c
>> @@ -207,3 +207,11 @@ int __init default_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
>>   	}
>>   	return 0;
>>   }
>> +
>> +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;
>> +}
>> diff --git a/arch/x86/kernel/apic/probe_64.c b/arch/x86/kernel/apic/probe_64.c
>> index c46720f185c0..986dbb68d3c4 100644
>> --- a/arch/x86/kernel/apic/probe_64.c
>> +++ b/arch/x86/kernel/apic/probe_64.c
>> @@ -50,3 +50,11 @@ int __init default_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
>>   	}
>>   	return 0;
>>   }
>> +
>> +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;
>> +}
> 
> What's the reason for having two verbatim copies of the same function
> which has no dependency on CONFIG_*_32/64 at all?

Initially I thought all ACPI related functions are grouped in probe_*.c.
After some review, now I know its incorrect. I will move the function
definition to apic.c

> 
> Thanks,
> 
>          tglx
>
diff mbox series

Patch

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..a4a6b97910e1 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -65,6 +65,9 @@  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;
+
 #ifdef CONFIG_X86_IO_APIC
 /*
  * Locks related to IOAPIC hotplug
@@ -329,6 +332,29 @@  acpi_parse_lapic_nmi(union acpi_subtable_headers * header, const unsigned long e
 	return 0;
 }
 
+static void acpi_mp_wake_mailbox_init(void)
+{
+	if (acpi_mp_wake_mailbox)
+		return;
+
+	acpi_mp_wake_mailbox = memremap(acpi_mp_wake_mailbox_paddr,
+			sizeof(*acpi_mp_wake_mailbox), MEMREMAP_WB);
+}
+
+static int acpi_wakeup_cpu(int apicid, unsigned long start_ip)
+{
+	acpi_mp_wake_mailbox_init();
+
+	if (!acpi_mp_wake_mailbox)
+		return -EINVAL;
+
+	WRITE_ONCE(acpi_mp_wake_mailbox->apic_id, apicid);
+	WRITE_ONCE(acpi_mp_wake_mailbox->wakeup_vector, start_ip);
+	WRITE_ONCE(acpi_mp_wake_mailbox->command, ACPI_MP_WAKE_COMMAND_WAKEUP);
+
+	return 0;
+}
+
 #endif				/*CONFIG_X86_LOCAL_APIC */
 
 #ifdef CONFIG_X86_IO_APIC
@@ -1086,6 +1112,30 @@  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 +1334,12 @@  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/probe_32.c b/arch/x86/kernel/apic/probe_32.c
index a61f642b1b90..d450014841b2 100644
--- a/arch/x86/kernel/apic/probe_32.c
+++ b/arch/x86/kernel/apic/probe_32.c
@@ -207,3 +207,11 @@  int __init default_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
 	}
 	return 0;
 }
+
+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;
+}
diff --git a/arch/x86/kernel/apic/probe_64.c b/arch/x86/kernel/apic/probe_64.c
index c46720f185c0..986dbb68d3c4 100644
--- a/arch/x86/kernel/apic/probe_64.c
+++ b/arch/x86/kernel/apic/probe_64.c
@@ -50,3 +50,11 @@  int __init default_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
 	}
 	return 0;
 }
+
+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;
+}