Commit 2b5e22af authored by Kiryl Shutsemau's avatar Kiryl Shutsemau Committed by Borislav Petkov (AMD)
Browse files

x86/acpi: Extract ACPI MADT wakeup code into a separate file 



In order to prepare for the expansion of support for the ACPI MADT
wakeup method, move the relevant code into a separate file.

Introduce a new configuration option to clearly indicate dependencies
without the use of ifdefs.

There have been no functional changes.

Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: default avatarBaoquan He <bhe@redhat.com>
Reviewed-by: default avatarKuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Acked-by: default avatarKai Huang <kai.huang@intel.com>
Acked-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: default avatarTao Liu <ltao@redhat.com>
Link: https://lore.kernel.org/r/20240614095904.1345461-2-kirill.shutemov@linux.intel.com
parent 54183d10

arch/x86/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -1118,6 +1118,13 @@ config X86_LOCAL_APIC 
	depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI

	select IRQ_DOMAIN_HIERARCHY



config ACPI_MADT_WAKEUP

	def_bool y

	depends on X86_64

	depends on ACPI

	depends on SMP

	depends on X86_LOCAL_APIC



config X86_IO_APIC

	def_bool y

	depends on X86_LOCAL_APIC || X86_UP_IOAPIC

arch/x86/include/asm/acpi.h

+5 −0
Original line number Diff line number Diff line
@@ -78,6 +78,11 @@ static inline bool acpi_skip_set_wakeup_address(void) 


#define acpi_skip_set_wakeup_address acpi_skip_set_wakeup_address



union acpi_subtable_headers;



int __init acpi_parse_mp_wake(union acpi_subtable_headers *header,

			      const unsigned long end);



/*

 * Check if the CPU can handle C2 and deeper

 */

arch/x86/kernel/acpi/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ obj-$(CONFIG_ACPI) += boot.o 
obj-$(CONFIG_ACPI_SLEEP)	+= sleep.o wakeup_$(BITS).o

obj-$(CONFIG_ACPI_APEI)		+= apei.o

obj-$(CONFIG_ACPI_CPPC_LIB)	+= cppc.o

obj-$(CONFIG_ACPI_MADT_WAKEUP)	+= madt_wakeup.o



ifneq ($(CONFIG_ACPI_PROCESSOR),)

obj-y				+= cstate.o

arch/x86/kernel/acpi/boot.c

+1 −85
Original line number Diff line number Diff line
@@ -67,13 +67,6 @@ static bool has_lapic_cpus __initdata; 
static bool acpi_support_online_capable;

#endif



#ifdef CONFIG_X86_64

/* Physical address of the Multiprocessor Wakeup Structure mailbox */

static u64 acpi_mp_wake_mailbox_paddr;

/* Virtual address of the Multiprocessor Wakeup Structure mailbox */

static struct acpi_madt_multiproc_wakeup_mailbox *acpi_mp_wake_mailbox;

#endif



#ifdef CONFIG_X86_IO_APIC

/*

 * Locks related to IOAPIC hotplug
@@ -341,60 +334,6 @@ acpi_parse_lapic_nmi(union acpi_subtable_headers * header, const unsigned long e 


	return 0;

}



#ifdef CONFIG_X86_64

static int acpi_wakeup_cpu(u32 apicid, unsigned long start_ip)

{

	/*

	 * Remap mailbox memory only for the first call to acpi_wakeup_cpu().

	 *

	 * Wakeup of secondary CPUs is fully serialized in the core code.

	 * No need to protect acpi_mp_wake_mailbox from concurrent accesses.

	 */

	if (!acpi_mp_wake_mailbox) {

		acpi_mp_wake_mailbox = memremap(acpi_mp_wake_mailbox_paddr,

						sizeof(*acpi_mp_wake_mailbox),

						MEMREMAP_WB);

	}



	/*

	 * Mailbox memory is shared between the firmware and OS. Firmware will

	 * listen on mailbox command address, and once it receives the wakeup

	 * command, the CPU associated with the given apicid will be booted.

	 *

	 * The value of 'apic_id' and 'wakeup_vector' must be visible to the

	 * firmware before the wakeup command is visible.  smp_store_release()

	 * ensures ordering and visibility.

	 */

	acpi_mp_wake_mailbox->apic_id	    = apicid;

	acpi_mp_wake_mailbox->wakeup_vector = start_ip;

	smp_store_release(&acpi_mp_wake_mailbox->command,

			  ACPI_MP_WAKE_COMMAND_WAKEUP);



	/*

	 * Wait for the CPU to wake up.

	 *

	 * The CPU being woken up is essentially in a spin loop waiting to be

	 * woken up. It should not take long for it wake up and acknowledge by

	 * zeroing out ->command.

	 *

	 * ACPI specification doesn't provide any guidance on how long kernel

	 * has to wait for a wake up acknowledgement. It also doesn't provide

	 * a way to cancel a wake up request if it takes too long.

	 *

	 * In TDX environment, the VMM has control over how long it takes to

	 * wake up secondary. It can postpone scheduling secondary vCPU

	 * indefinitely. Giving up on wake up request and reporting error opens

	 * possible attack vector for VMM: it can wake up a secondary CPU when

	 * kernel doesn't expect it. Wait until positive result of the wake up

	 * request.

	 */

	while (READ_ONCE(acpi_mp_wake_mailbox->command))

		cpu_relax();



	return 0;

}

#endif /* CONFIG_X86_64 */

#endif /* CONFIG_X86_LOCAL_APIC */



#ifdef CONFIG_X86_IO_APIC
@@ -1124,29 +1063,6 @@ static int __init acpi_parse_madt_lapic_entries(void) 
	}

	return 0;

}



#ifdef CONFIG_X86_64

static int __init acpi_parse_mp_wake(union acpi_subtable_headers *header,

				     const unsigned long end)

{

	struct acpi_madt_multiproc_wakeup *mp_wake;



	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;



	apic_update_callback(wakeup_secondary_cpu_64, acpi_wakeup_cpu);



	return 0;

}

#endif				/* CONFIG_X86_64 */

#endif				/* CONFIG_X86_LOCAL_APIC */



#ifdef	CONFIG_X86_IO_APIC
@@ -1343,7 +1259,7 @@ static void __init acpi_process_madt(void) 
				smp_found_config = 1;

			}



#ifdef CONFIG_X86_64

#ifdef CONFIG_ACPI_MADT_WAKEUP

			/*

			 * Parse MADT MP Wake entry.

			 */

arch/x86/kernel/acpi/madt_wakeup.c

0 → 100644
+82 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-or-later

#include <linux/acpi.h>

#include <linux/io.h>

#include <asm/apic.h>

#include <asm/barrier.h>

#include <asm/processor.h>



/* Physical address of the Multiprocessor Wakeup Structure mailbox */

static u64 acpi_mp_wake_mailbox_paddr;



/* Virtual address of the Multiprocessor Wakeup Structure mailbox */

static struct acpi_madt_multiproc_wakeup_mailbox *acpi_mp_wake_mailbox;



static int acpi_wakeup_cpu(u32 apicid, unsigned long start_ip)

{

	/*

	 * Remap mailbox memory only for the first call to acpi_wakeup_cpu().

	 *

	 * Wakeup of secondary CPUs is fully serialized in the core code.

	 * No need to protect acpi_mp_wake_mailbox from concurrent accesses.

	 */

	if (!acpi_mp_wake_mailbox) {

		acpi_mp_wake_mailbox = memremap(acpi_mp_wake_mailbox_paddr,

						sizeof(*acpi_mp_wake_mailbox),

						MEMREMAP_WB);

	}



	/*

	 * Mailbox memory is shared between the firmware and OS. Firmware will

	 * listen on mailbox command address, and once it receives the wakeup

	 * command, the CPU associated with the given apicid will be booted.

	 *

	 * The value of 'apic_id' and 'wakeup_vector' must be visible to the

	 * firmware before the wakeup command is visible.  smp_store_release()

	 * ensures ordering and visibility.

	 */

	acpi_mp_wake_mailbox->apic_id	    = apicid;

	acpi_mp_wake_mailbox->wakeup_vector = start_ip;

	smp_store_release(&acpi_mp_wake_mailbox->command,

			  ACPI_MP_WAKE_COMMAND_WAKEUP);



	/*

	 * Wait for the CPU to wake up.

	 *

	 * The CPU being woken up is essentially in a spin loop waiting to be

	 * woken up. It should not take long for it wake up and acknowledge by

	 * zeroing out ->command.

	 *

	 * ACPI specification doesn't provide any guidance on how long kernel

	 * has to wait for a wake up acknowledgment. It also doesn't provide

	 * a way to cancel a wake up request if it takes too long.

	 *

	 * In TDX environment, the VMM has control over how long it takes to

	 * wake up secondary. It can postpone scheduling secondary vCPU

	 * indefinitely. Giving up on wake up request and reporting error opens

	 * possible attack vector for VMM: it can wake up a secondary CPU when

	 * kernel doesn't expect it. Wait until positive result of the wake up

	 * request.

	 */

	while (READ_ONCE(acpi_mp_wake_mailbox->command))

		cpu_relax();



	return 0;

}



int __init acpi_parse_mp_wake(union acpi_subtable_headers *header,

			      const unsigned long end)

{

	struct acpi_madt_multiproc_wakeup *mp_wake;



	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;



	apic_update_callback(wakeup_secondary_cpu_64, acpi_wakeup_cpu);



	return 0;

}