diff mbox series

[RFC,13/22] arm64: setup: Switch over to GENERIC_CPU_DEVICES using arch_register_cpu()

Message ID E1r0JLl-00CTxk-7O@rmk-PC.armlinux.org.uk
State New
Headers show
Series Initial cleanups for vCPU hotplug | expand

Commit Message

Russell King (Oracle) Nov. 7, 2023, 10:30 a.m. UTC 
From: James Morse <james.morse@arm.com>

To allow ACPI's _STA value to hide CPUs that are present, but not
available to online right now due to VMM or firmware policy, the
register_cpu() call needs to be made by the ACPI machinery when ACPI
is in use. This allows it to hide CPUs that are unavailable from sysfs.

Switching to GENERIC_CPU_DEVICES is an intermediate step to allow all
five ACPI architectures to be modified at once.

Switch over to GENERIC_CPU_DEVICES, and provide an arch_register_cpu()
that populates the hotpluggable flag. arch_register_cpu() is also the
interface the ACPI machinery expects.

The struct cpu in struct cpuinfo_arm64 is never used directly, remove
it to use the one GENERIC_CPU_DEVICES provides.

This changes the CPUs visible in sysfs from possible to present, but
on arm64 smp_prepare_cpus() ensures these are the same.

This patch also has the effect of moving the registration of CPUs from
subsys to driver core initialisation, prior to any initcalls running.

Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
---
Changes since RFC v2:
 * Add note about initialisation order change.
---
 arch/arm64/Kconfig           |  1 +
 arch/arm64/include/asm/cpu.h |  1 -
 arch/arm64/kernel/setup.c    | 13 ++++---------
 3 files changed, 5 insertions(+), 10 deletions(-)

Comments

Shaoqin Huang Nov. 10, 2023, 3:36 a.m. UTC | #1 
On 11/7/23 18:30, Russell King (Oracle) wrote:
> From: James Morse <james.morse@arm.com>
> 
> To allow ACPI's _STA value to hide CPUs that are present, but not
> available to online right now due to VMM or firmware policy, the
> register_cpu() call needs to be made by the ACPI machinery when ACPI
> is in use. This allows it to hide CPUs that are unavailable from sysfs.
> 
> Switching to GENERIC_CPU_DEVICES is an intermediate step to allow all
> five ACPI architectures to be modified at once.
> 
> Switch over to GENERIC_CPU_DEVICES, and provide an arch_register_cpu()
> that populates the hotpluggable flag. arch_register_cpu() is also the
> interface the ACPI machinery expects.
> 
> The struct cpu in struct cpuinfo_arm64 is never used directly, remove
> it to use the one GENERIC_CPU_DEVICES provides.
> 
> This changes the CPUs visible in sysfs from possible to present, but
> on arm64 smp_prepare_cpus() ensures these are the same.
> 
> This patch also has the effect of moving the registration of CPUs from
> subsys to driver core initialisation, prior to any initcalls running.
> 
> Signed-off-by: James Morse <james.morse@arm.com>
> Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Shaoqin Huang <shahuang@redhat.com>
> ---
> Changes since RFC v2:
>   * Add note about initialisation order change.
> ---
>   arch/arm64/Kconfig           |  1 +
>   arch/arm64/include/asm/cpu.h |  1 -
>   arch/arm64/kernel/setup.c    | 13 ++++---------
>   3 files changed, 5 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 7b071a00425d..84bce830e365 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -132,6 +132,7 @@ config ARM64
>   	select GENERIC_ARCH_TOPOLOGY
>   	select GENERIC_CLOCKEVENTS_BROADCAST
>   	select GENERIC_CPU_AUTOPROBE
> +	select GENERIC_CPU_DEVICES
>   	select GENERIC_CPU_VULNERABILITIES
>   	select GENERIC_EARLY_IOREMAP
>   	select GENERIC_IDLE_POLL_SETUP
> diff --git a/arch/arm64/include/asm/cpu.h b/arch/arm64/include/asm/cpu.h
> index f3034099fd95..b1e43f56ee46 100644
> --- a/arch/arm64/include/asm/cpu.h
> +++ b/arch/arm64/include/asm/cpu.h
> @@ -38,7 +38,6 @@ struct cpuinfo_32bit {
>   };
>   
>   struct cpuinfo_arm64 {
> -	struct cpu	cpu;
>   	struct kobject	kobj;
>   	u64		reg_ctr;
>   	u64		reg_cntfrq;
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index 417a8a86b2db..165bd2c0dd5a 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -402,19 +402,14 @@ static inline bool cpu_can_disable(unsigned int cpu)
>   	return false;
>   }
>   
> -static int __init topology_init(void)
> +int arch_register_cpu(int num)
>   {
> -	int i;
> +	struct cpu *cpu = &per_cpu(cpu_devices, num);
>   
> -	for_each_possible_cpu(i) {
> -		struct cpu *cpu = &per_cpu(cpu_data.cpu, i);
> -		cpu->hotpluggable = cpu_can_disable(i);
> -		register_cpu(cpu, i);
> -	}
> +	cpu->hotpluggable = cpu_can_disable(num);
>   
> -	return 0;
> +	return register_cpu(cpu, num);
>   }
> -subsys_initcall(topology_init);
>   
>   static void dump_kernel_offset(void)
>   {
Gavin Shan Nov. 13, 2023, 4:07 a.m. UTC | #2 
On 11/7/23 20:30, Russell King (Oracle) wrote:
> From: James Morse <james.morse@arm.com>
> 
> To allow ACPI's _STA value to hide CPUs that are present, but not
> available to online right now due to VMM or firmware policy, the
> register_cpu() call needs to be made by the ACPI machinery when ACPI
> is in use. This allows it to hide CPUs that are unavailable from sysfs.
> 
> Switching to GENERIC_CPU_DEVICES is an intermediate step to allow all
> five ACPI architectures to be modified at once.
> 
> Switch over to GENERIC_CPU_DEVICES, and provide an arch_register_cpu()
> that populates the hotpluggable flag. arch_register_cpu() is also the
> interface the ACPI machinery expects.
> 
> The struct cpu in struct cpuinfo_arm64 is never used directly, remove
> it to use the one GENERIC_CPU_DEVICES provides.
> 
> This changes the CPUs visible in sysfs from possible to present, but
> on arm64 smp_prepare_cpus() ensures these are the same.
> 
> This patch also has the effect of moving the registration of CPUs from
> subsys to driver core initialisation, prior to any initcalls running.
> 
> Signed-off-by: James Morse <james.morse@arm.com>
> Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> ---
> Changes since RFC v2:
>   * Add note about initialisation order change.
> ---
>   arch/arm64/Kconfig           |  1 +
>   arch/arm64/include/asm/cpu.h |  1 -
>   arch/arm64/kernel/setup.c    | 13 ++++---------
>   3 files changed, 5 insertions(+), 10 deletions(-)
> 

Reviewed-by: Gavin Shan <gshan@redhat.com>
Jonathan Cameron Nov. 28, 2023, 3:08 p.m. UTC | #3 
On Tue, 07 Nov 2023 10:30:25 +0000
Russell King <rmk+kernel@armlinux.org.uk> wrote:

> From: James Morse <james.morse@arm.com>
> 
> To allow ACPI's _STA value to hide CPUs that are present, but not
> available to online right now due to VMM or firmware policy, the
> register_cpu() call needs to be made by the ACPI machinery when ACPI
> is in use. This allows it to hide CPUs that are unavailable from sysfs.
> 
> Switching to GENERIC_CPU_DEVICES is an intermediate step to allow all
> five ACPI architectures to be modified at once.
> 
> Switch over to GENERIC_CPU_DEVICES, and provide an arch_register_cpu()
> that populates the hotpluggable flag. arch_register_cpu() is also the
> interface the ACPI machinery expects.
> 
> The struct cpu in struct cpuinfo_arm64 is never used directly, remove
> it to use the one GENERIC_CPU_DEVICES provides.
> 
> This changes the CPUs visible in sysfs from possible to present, but
> on arm64 smp_prepare_cpus() ensures these are the same.
> 
> This patch also has the effect of moving the registration of CPUs from
> subsys to driver core initialisation, prior to any initcalls running.
> 
> Signed-off-by: James Morse <james.morse@arm.com>
> Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

Given this series adds an arch_cpu_is_hotpluggable() callback we probably
want something in this patch description to say why this
isn't using that, but instead overriding arch_register_cpu()

Jonathan

> ---
> Changes since RFC v2:
>  * Add note about initialisation order change.
> ---
>  arch/arm64/Kconfig           |  1 +
>  arch/arm64/include/asm/cpu.h |  1 -
>  arch/arm64/kernel/setup.c    | 13 ++++---------
>  3 files changed, 5 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 7b071a00425d..84bce830e365 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -132,6 +132,7 @@ config ARM64
>  	select GENERIC_ARCH_TOPOLOGY
>  	select GENERIC_CLOCKEVENTS_BROADCAST
>  	select GENERIC_CPU_AUTOPROBE
> +	select GENERIC_CPU_DEVICES
>  	select GENERIC_CPU_VULNERABILITIES
>  	select GENERIC_EARLY_IOREMAP
>  	select GENERIC_IDLE_POLL_SETUP
> diff --git a/arch/arm64/include/asm/cpu.h b/arch/arm64/include/asm/cpu.h
> index f3034099fd95..b1e43f56ee46 100644
> --- a/arch/arm64/include/asm/cpu.h
> +++ b/arch/arm64/include/asm/cpu.h
> @@ -38,7 +38,6 @@ struct cpuinfo_32bit {
>  };
>  
>  struct cpuinfo_arm64 {
> -	struct cpu	cpu;
>  	struct kobject	kobj;
>  	u64		reg_ctr;
>  	u64		reg_cntfrq;
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index 417a8a86b2db..165bd2c0dd5a 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -402,19 +402,14 @@ static inline bool cpu_can_disable(unsigned int cpu)
>  	return false;
>  }
>  
> -static int __init topology_init(void)
> +int arch_register_cpu(int num)
>  {
> -	int i;
> +	struct cpu *cpu = &per_cpu(cpu_devices, num);
>  
> -	for_each_possible_cpu(i) {
> -		struct cpu *cpu = &per_cpu(cpu_data.cpu, i);
> -		cpu->hotpluggable = cpu_can_disable(i);
> -		register_cpu(cpu, i);
> -	}
> +	cpu->hotpluggable = cpu_can_disable(num);
>  
> -	return 0;
> +	return register_cpu(cpu, num);
>  }
> -subsys_initcall(topology_init);
>  
>  static void dump_kernel_offset(void)
>  {
Jonathan Cameron Nov. 28, 2023, 3:12 p.m. UTC | #4 
On Tue, 28 Nov 2023 15:08:54 +0000
Jonathan Cameron <Jonathan.Cameron@Huawei.com> wrote:

> On Tue, 07 Nov 2023 10:30:25 +0000
> Russell King <rmk+kernel@armlinux.org.uk> wrote:
> 
> > From: James Morse <james.morse@arm.com>
> > 
> > To allow ACPI's _STA value to hide CPUs that are present, but not
> > available to online right now due to VMM or firmware policy, the
> > register_cpu() call needs to be made by the ACPI machinery when ACPI
> > is in use. This allows it to hide CPUs that are unavailable from sysfs.
> > 
> > Switching to GENERIC_CPU_DEVICES is an intermediate step to allow all
> > five ACPI architectures to be modified at once.
> > 
> > Switch over to GENERIC_CPU_DEVICES, and provide an arch_register_cpu()
> > that populates the hotpluggable flag. arch_register_cpu() is also the
> > interface the ACPI machinery expects.
> > 
> > The struct cpu in struct cpuinfo_arm64 is never used directly, remove
> > it to use the one GENERIC_CPU_DEVICES provides.
> > 
> > This changes the CPUs visible in sysfs from possible to present, but
> > on arm64 smp_prepare_cpus() ensures these are the same.
> > 
> > This patch also has the effect of moving the registration of CPUs from
> > subsys to driver core initialisation, prior to any initcalls running.
> > 
> > Signed-off-by: James Morse <james.morse@arm.com>
> > Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> > Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>  
> 
> Given this series adds an arch_cpu_is_hotpluggable() callback we probably
> want something in this patch description to say why this
> isn't using that, but instead overriding arch_register_cpu()
> 
As per comment on next patch I'm fine with this slight dance.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
diff mbox series

Patch

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 7b071a00425d..84bce830e365 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -132,6 +132,7 @@  config ARM64
 	select GENERIC_ARCH_TOPOLOGY
 	select GENERIC_CLOCKEVENTS_BROADCAST
 	select GENERIC_CPU_AUTOPROBE
+	select GENERIC_CPU_DEVICES
 	select GENERIC_CPU_VULNERABILITIES
 	select GENERIC_EARLY_IOREMAP
 	select GENERIC_IDLE_POLL_SETUP
diff --git a/arch/arm64/include/asm/cpu.h b/arch/arm64/include/asm/cpu.h
index f3034099fd95..b1e43f56ee46 100644
--- a/arch/arm64/include/asm/cpu.h
+++ b/arch/arm64/include/asm/cpu.h
@@ -38,7 +38,6 @@  struct cpuinfo_32bit {
 };
 
 struct cpuinfo_arm64 {
-	struct cpu	cpu;
 	struct kobject	kobj;
 	u64		reg_ctr;
 	u64		reg_cntfrq;
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 417a8a86b2db..165bd2c0dd5a 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -402,19 +402,14 @@  static inline bool cpu_can_disable(unsigned int cpu)
 	return false;
 }
 
-static int __init topology_init(void)
+int arch_register_cpu(int num)
 {
-	int i;
+	struct cpu *cpu = &per_cpu(cpu_devices, num);
 
-	for_each_possible_cpu(i) {
-		struct cpu *cpu = &per_cpu(cpu_data.cpu, i);
-		cpu->hotpluggable = cpu_can_disable(i);
-		register_cpu(cpu, i);
-	}
+	cpu->hotpluggable = cpu_can_disable(num);
 
-	return 0;
+	return register_cpu(cpu, num);
 }
-subsys_initcall(topology_init);
 
 static void dump_kernel_offset(void)
 {