[PATCH v4 1/3] xen/arm: Enable cpu_hotplug.c

[Stefano Stabellini]

CC'ing few more x86 people as it contains a few x86 changes.

If you are OK with this, I'll go ahead and apply the series to
xentip/for-linus-4.4.

On Wed, 21 Oct 2015, Stefano Stabellini wrote:
> Build cpu_hotplug for ARM and ARM64 guests.
> 
> Rename arch_(un)register_cpu to xen_(un)register_cpu and provide an
> empty implementation on ARM and ARM64. On x86 just call
> arch_(un)register_cpu as we are already doing.
> 
> Initialize cpu_hotplug on ARM.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini at eu.citrix.com>
> Reviewed-by: Julien Grall <julien.grall at citrix.com>
> 
> ---
> 
> Changes in v2:
> - don't initialize if not a xen_domain() on arm
> - protect xen_arch_(un)register_cpu with ifdef CONFIG_HOTPLUG_CPU on arm
> ---
>  arch/arm/include/asm/xen/hypervisor.h |   10 ++++++++++
>  arch/x86/include/asm/xen/hypervisor.h |    5 +++++
>  arch/x86/xen/enlighten.c              |   15 +++++++++++++++
>  drivers/xen/Makefile                  |    2 --
>  drivers/xen/cpu_hotplug.c             |    8 ++++++--
>  5 files changed, 36 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm/include/asm/xen/hypervisor.h b/arch/arm/include/asm/xen/hypervisor.h
> index 04ff8e7..9525151 100644
> --- a/arch/arm/include/asm/xen/hypervisor.h
> +++ b/arch/arm/include/asm/xen/hypervisor.h
> @@ -26,4 +26,14 @@ void __init xen_early_init(void);
>  static inline void xen_early_init(void) { return; }
>  #endif
>  
> +#ifdef CONFIG_HOTPLUG_CPU
> +static inline void xen_arch_register_cpu(int num)
> +{
> +}
> +
> +static inline void xen_arch_unregister_cpu(int num)
> +{
> +}
> +#endif
> +
>  #endif /* _ASM_ARM_XEN_HYPERVISOR_H */
> diff --git a/arch/x86/include/asm/xen/hypervisor.h b/arch/x86/include/asm/xen/hypervisor.h
> index d866959..8b2d4be 100644
> --- a/arch/x86/include/asm/xen/hypervisor.h
> +++ b/arch/x86/include/asm/xen/hypervisor.h
> @@ -57,4 +57,9 @@ static inline bool xen_x2apic_para_available(void)
>  }
>  #endif
>  
> +#ifdef CONFIG_HOTPLUG_CPU
> +void xen_arch_register_cpu(int num);
> +void xen_arch_unregister_cpu(int num);
> +#endif
> +
>  #endif /* _ASM_X86_XEN_HYPERVISOR_H */
> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> index 11d6fb4..ba62d8e 100644
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -71,6 +71,7 @@
>  #include <asm/mwait.h>
>  #include <asm/pci_x86.h>
>  #include <asm/pat.h>
> +#include <asm/cpu.h>
>  
>  #ifdef CONFIG_ACPI
>  #include <linux/acpi.h>
> @@ -1868,3 +1869,17 @@ const struct hypervisor_x86 x86_hyper_xen = {
>  	.set_cpu_features       = xen_set_cpu_features,
>  };
>  EXPORT_SYMBOL(x86_hyper_xen);
> +
> +#ifdef CONFIG_HOTPLUG_CPU
> +void xen_arch_register_cpu(int num)
> +{
> +	arch_register_cpu(num);
> +}
> +EXPORT_SYMBOL(xen_arch_register_cpu);
> +
> +void xen_arch_unregister_cpu(int num)
> +{
> +	arch_unregister_cpu(num);
> +}
> +EXPORT_SYMBOL(xen_arch_unregister_cpu);
> +#endif
> diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
> index e293bc5..aa8a7f7 100644
> --- a/drivers/xen/Makefile
> +++ b/drivers/xen/Makefile
> @@ -1,6 +1,4 @@
> -ifeq ($(filter y, $(CONFIG_ARM) $(CONFIG_ARM64)),)
>  obj-$(CONFIG_HOTPLUG_CPU)		+= cpu_hotplug.o
> -endif
>  obj-$(CONFIG_X86)			+= fallback.o
>  obj-y	+= grant-table.o features.o balloon.o manage.o preempt.o
>  obj-y	+= events/
> diff --git a/drivers/xen/cpu_hotplug.c b/drivers/xen/cpu_hotplug.c
> index cc6513a..43de1f5 100644
> --- a/drivers/xen/cpu_hotplug.c
> +++ b/drivers/xen/cpu_hotplug.c
> @@ -11,7 +11,7 @@
>  static void enable_hotplug_cpu(int cpu)
>  {
>  	if (!cpu_present(cpu))
> -		arch_register_cpu(cpu);
> +		xen_arch_register_cpu(cpu);
>  
>  	set_cpu_present(cpu, true);
>  }
> @@ -19,7 +19,7 @@ static void enable_hotplug_cpu(int cpu)
>  static void disable_hotplug_cpu(int cpu)
>  {
>  	if (cpu_present(cpu))
> -		arch_unregister_cpu(cpu);
> +		xen_arch_unregister_cpu(cpu);
>  
>  	set_cpu_present(cpu, false);
>  }
> @@ -102,7 +102,11 @@ static int __init setup_vcpu_hotplug_event(void)
>  	static struct notifier_block xsn_cpu = {
>  		.notifier_call = setup_cpu_watcher };
>  
> +#ifdef CONFIG_X86
>  	if (!xen_pv_domain())
> +#else
> +	if (!xen_domain())
> +#endif
>  		return -ENODEV;
>  
>  	register_xenstore_notifier(&xsn_cpu);
> -- 
> 1.7.10.4
>