Unverified Commit fe0d22a2 authored by openeuler-ci-bot's avatar openeuler-ci-bot Committed by Gitee
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!5555 v2 ACPI/arm64: add support for virtual cpu hotplug 

Merge Pull Request from: @ci-robot 
 
PR sync from: liwei <liwei728@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/ZIRDZR7EE4QCX5PIDKMIYUWJN3TEC6DW/ 
This is this remaining patches for ARM64 virtual cpu hotplug, which
follows on from the previous set of 21 patches that GregKH has
recently queued up, and "x86: intel_epb: Don't rely on link order"
which can be found at:

https://lore.kernel.org/r/ZVyz/Ve5pPu8AWoA@shell.armlinux.org.uk

James Morse (19):
  ACPI: Only enumerate enabled (or functional) devices
  ACPI: processor: Add support for processors described as container
    packages
  ACPI: processor: Register CPUs that are online, but not described in
    the DSDT
  ACPI: processor: Register all CPUs from acpi_processor_get_info()
  ACPI: Rename ACPI_HOTPLUG_CPU to include 'present'
  ACPI: Move acpi_bus_trim_one() before acpi_scan_hot_remove()
  ACPI: Rename acpi_processor_hotadd_init and remove pre-processor
    guards
  ACPI: Add post_eject to struct acpi_scan_handler for cpu hotplug
  ACPI: Check _STA present bit before making CPUs not present
  ACPI: Warn when the present bit changes but the feature is not enabled
  arm64: acpi: Move get_cpu_for_acpi_id() to a header
  ACPICA: Add new MADT GICC flags fields
  irqchip/gic-v3: Don't return errors from gic_acpi_match_gicc()
  irqchip/gic-v3: Add support for ACPI's disabled but 'online capable'
    CPUs
  ACPI: add support to register CPUs based on the _STA enabled bit
  ACPI: processor: Only call arch_unregister_cpu() if HOTPLUG_CPU is
    selected
  arm64: document virtual CPU hotplug's expectations
  ACPI: Add _OSC bits to advertise OS support for toggling CPU
    present/enabled
  cpumask: Add enabled cpumask for present CPUs that can be brought
    online

Jean-Philippe Brucker (1):
  arm64: psci: Ignore DENIED CPUs

Russell King (Oracle) (1):
  ACPI: convert acpi_processor_post_eject() to use IS_ENABLED()

liwei (1):
  arm64/psci: Add undefined error message printing for psci_x_cpu_on


-- 
2.25.1
 
https://gitee.com/openeuler/kernel/issues/I8XMTL 
 
Link:https://gitee.com/openeuler/kernel/pulls/5555

 

Reviewed-by: default avatarWeilong Chen <chenweilong@huawei.com>
Reviewed-by: default avatarWei Li <liwei391@huawei.com>
Reviewed-by: default avatarZhang Jianhua <chris.zjh@huawei.com>
Reviewed-by: default avatarMao Bibo <maobibo@loongson.cn>
Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
parents 70460587 c5a9c0d2

Documentation/arch/arm64/cpu-hotplug.rst

0 → 100644
+79 −0
Original line number Diff line number Diff line 
.. SPDX-License-Identifier: GPL-2.0

.. _cpuhp_index:



====================

CPU Hotplug and ACPI

====================



CPU hotplug in the arm64 world is commonly used to describe the kernel taking

CPUs online/offline using PSCI. This document is about ACPI firmware allowing

CPUs that were not available during boot to be added to the system later.



``possible`` and ``present`` refer to the state of the CPU as seen by linux.





CPU Hotplug on physical systems - CPUs not present at boot

----------------------------------------------------------



Physical systems need to mark a CPU that is ``possible`` but not ``present`` as

being ``present``. An example would be a dual socket machine, where the package

in one of the sockets can be replaced while the system is running.



This is not supported.



In the arm64 world CPUs are not a single device but a slice of the system.

There are no systems that support the physical addition (or removal) of CPUs

while the system is running, and ACPI is not able to sufficiently describe

them.



e.g. New CPUs come with new caches, but the platform's cache toplogy is

described in a static table, the PPTT. How caches are shared between CPUs is

not discoverable, and must be described by firmware.



e.g. The GIC redistributor for each CPU must be accessed by the driver during

boot to discover the system wide supported features. ACPI's MADT GICC

structures can describe a redistributor associated with a disabled CPU, but

can't describe whether the redistributor is accessible, only that it is not

'always on'.



arm64's ACPI tables assume that everything described is ``present``.





CPU Hotplug on virtual systems - CPUs not enabled at boot

---------------------------------------------------------



Virtual systems have the advantage that all the properties the system will

ever have can be described at boot. There are no power-domain considerations

as such devices are emulated.



CPU Hotplug on virtual systems is supported. It is distinct from physical

CPU Hotplug as all resources are described as ``present``, but CPUs may be

marked as disabled by firmware. Only the CPU's online/offline behaviour is

influenced by firmware. An example is where a virtual machine boots with a

single CPU, and additional CPUs are added once a cloud orchestrator deploys

the workload.



For a virtual machine, the VMM (e.g. Qemu) plays the part of firmware.



Virtual hotplug is implemented as a firmware policy affecting which CPUs can be

brought online. Firmware can enforce its policy via PSCI's return codes. e.g.

``DENIED``.



The ACPI tables must describe all the resources of the virtual machine. CPUs

that firmware wishes to disable either from boot (or later) should not be

``enabled`` in the MADT GICC structures, but should have the ``online capable``

bit set, to indicate they can be enabled later. The boot CPU must be marked as

``enabled``.  The 'always on' GICR structure must be used to describe the

redistributors.



CPUs described as ``online capable`` but not ``enabled`` can be set to enabled

by the DSDT's Processor object's _STA method. On virtual systems the _STA method

must always report the CPU as ``present``. Changes to the firmware policy can

be notified to the OS via device-check or eject-request.



CPUs described as ``enabled`` in the static table, should not have their _STA

modified dynamically by firmware. Soft-restart features such as kexec will

re-read the static properties of the system from these static tables, and

may malfunction if these no longer describe the running system. Linux will

re-discover the dynamic properties of the system from the _STA method later

during boot.

Documentation/arch/arm64/index.rst

+1 −0
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@@ -13,6 +13,7 @@ ARM64 Architecture 
    asymmetric-32bit

    booting

    cpu-feature-registers

    cpu-hotplug

    elf_hwcaps

    hugetlbpage

    kdump

arch/arm64/include/asm/acpi.h

+11 −0
Original line number Diff line number Diff line
@@ -119,6 +119,17 @@ static inline u32 get_acpi_id_for_cpu(unsigned int cpu) 
	return	acpi_cpu_get_madt_gicc(cpu)->uid;

}



static inline int get_cpu_for_acpi_id(u32 uid)

{

	int cpu;



	for (cpu = 0; cpu < nr_cpu_ids; cpu++)

		if (uid == get_acpi_id_for_cpu(cpu))

			return cpu;



	return -EINVAL;

}



static inline void arch_fix_phys_package_id(int num, u32 slot) { }

void __init acpi_init_cpus(void);

int apei_claim_sea(struct pt_regs *regs);

arch/arm64/kernel/acpi_numa.c

+0 −11
Original line number Diff line number Diff line
@@ -34,17 +34,6 @@ int __init acpi_numa_get_nid(unsigned int cpu) 
	return acpi_early_node_map[cpu];

}



static inline int get_cpu_for_acpi_id(u32 uid)

{

	int cpu;



	for (cpu = 0; cpu < nr_cpu_ids; cpu++)

		if (uid == get_acpi_id_for_cpu(cpu))

			return cpu;



	return -EINVAL;

}



static int __init acpi_parse_gicc_pxm(union acpi_subtable_headers *header,

				      const unsigned long end)

{

arch/arm64/kernel/psci.c

+6 −2
Original line number Diff line number Diff line
@@ -40,8 +40,12 @@ static int cpu_psci_cpu_boot(unsigned int cpu) 
{

	phys_addr_t pa_secondary_entry = __pa_symbol(secondary_entry);

	int err = psci_ops.cpu_on(cpu_logical_map(cpu), pa_secondary_entry);

	if (err)

	if (err) {

		if (err != -EPERM)

			pr_err("failed to boot CPU%d (%d)\n", cpu, err);

		else

			pr_err("psci feedback boot CPU%d result(%d) undefined\n", cpu, err);

	}



	return err;

}