Subject: [Suggestion] arch: arm64: xen: "ln -s" the paravirt.h from arm.

From: [email-masked] (Chen Gang)
Date: Tue, 25 Jun 2013 09:31:17 +0800

On 06/25/2013 12:50 AM, Stefano Stabellini wrote:
> On Mon, 24 Jun 2013, Stefano Stabellini wrote:
>> > On Mon, 24 Jun 2013, Chen Gang wrote:
>>> > > Hello Maintainers:
>>> > > 
>>> > > if 'CONFIG_XEN'
>>> > > 
>>> > >   CC      arch/arm64/xen/../../arm/xen/enlighten.o
>>> > > arch/arm64/xen/../../arm/xen/enlighten.c:19:26: fatal error: asm/paravirt.h: No such file or directory
>>> > > 
>>> > > The related .config file for next-20130624 is in attachment.
>>> > > 
>>> > > 
>>> > > If "ln -s ../../../arm/include/asm/paravirt.h paravirt.h", it can pass
>>> > > compiling, but I do not know how to make a patch for it ("ln -s ..."),
>>> > > Do we have another more suitable ways for it (or another fixing ways) ?
>>> > > 
>>> > > Welcome any suggestions or completions.
>> > 
>> > The problem is caused by:
>> > 
>> > commit 3a885582a366caf868b0782041c44854ff4c3568
>> > Author: Stefano Stabellini <[email-masked]>
>> > Date:   Wed May 29 10:56:34 2013 +0000
>> > 
>> >     xen/arm: account for stolen ticks
>> > 
>> > that is in my tree for linux-next (even though I have not received any
>> > replies from the ARM maintainers so I don't know when and if it is going
>> > to go upstream).
>> > 
>> > I think that the best thing to do would be to add a couple of ifdef
>> > CONFIG_PARAVIRT in arch/arm/xen/enlighten.c. I'll add them to my tree.
> Actually now that we have XEN support under arm64, we can just introduce the
> same pv_time_op struct and paravirt header that this patch
> 
> http://marc.info/?l=linux-arm-kernel&m=136992435301890&w=2
> 
> is introducing under arm.
> Any opinions?
> 

OK, thanks, and excuse me, I can not open the link above (the reason
maybe it can not be accessed from China).

But at least, the patch below is better than "ln -s" (which I provided).

Thanks.

> ---
> 
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 19c1cde..47bd26b 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -207,6 +207,25 @@ config FORCE_MAX_ZONEORDER
>  	default "14" if (ARM64_64K_PAGES && TRANSPARENT_HUGEPAGE)
>  	default "11"
>  
> +config PARAVIRT
> +	bool "Enable paravirtualization code"
> +	---help---
> +	  This changes the kernel so it can modify itself when it is run
> +	  under a hypervisor, potentially improving performance significantly
> +	  over full virtualization.
> +
> +config PARAVIRT_TIME_ACCOUNTING
> +	bool "Paravirtual steal time accounting"
> +	select PARAVIRT
> +	default n
> +	---help---
> +	  Select this option to enable fine granularity task steal time
> +	  accounting. Time spent executing other tasks in parallel with
> +	  the current vCPU is discounted from the vCPU power. To account for
> +	  that, there can be a small performance impact.
> +
> +	  If in doubt, say N here.
> +
>  config XEN_DOM0
>  	def_bool y
>  	depends on XEN
> @@ -214,6 +233,7 @@ config XEN_DOM0
>  config XEN
>  	bool "Xen guest support on ARM64 (EXPERIMENTAL)"
>  	depends on ARM64 && OF
> +	select PARAVIRT
>  	help
>  	  Say Y if you want to run Linux in a Virtual Machine on Xen on ARM64.
>  
> diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h
> new file mode 100644
> index 0000000..54e895b
> --- /dev/null
> +++ b/arch/arm64/include/asm/paravirt.h
> @@ -0,0 +1,19 @@
> +#ifndef _ASM_ARM64_PARAVIRT_H
> +#define _ASM_ARM64_PARAVIRT_H
> +
> +struct static_key;
> +extern struct static_key paravirt_steal_enabled;
> +extern struct static_key paravirt_steal_rq_enabled;
> +
> +struct pv_time_ops {
> +	unsigned long long (*steal_clock)(int cpu);
> +};
> +extern struct pv_time_ops pv_time_ops;
> +
> +static inline u64 paravirt_steal_clock(int cpu)
> +{
> +	return pv_time_ops.steal_clock(cpu);
> +}
> +
> +
> +#endif
> diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
> index 7b4b564..17613ad 100644
> --- a/arch/arm64/kernel/Makefile
> +++ b/arch/arm64/kernel/Makefile
> @@ -18,6 +18,7 @@ arm64-obj-$(CONFIG_SMP)			+= smp.o smp_spin_table.o smp_psci.o
>  arm64-obj-$(CONFIG_HW_PERF_EVENTS)	+= perf_event.o
>  arm64-obj-$(CONFIG_HAVE_HW_BREAKPOINT)+= hw_breakpoint.o
>  arm64-obj-$(CONFIG_EARLY_PRINTK)	+= early_printk.o
> +arm64-obj-$(CONFIG_PARAVIRT)		+= paravirt.o
>  
>  obj-y					+= $(arm64-obj-y) vdso/
>  obj-m					+= $(arm64-obj-m)
> diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c
> new file mode 100644
> index 0000000..53f371e
> --- /dev/null
> +++ b/arch/arm64/kernel/paravirt.c
> @@ -0,0 +1,25 @@
> +/*
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * Copyright (C) 2013 Citrix Systems
> + *
> + * Author: Stefano Stabellini <[email-masked]>
> + */
> +
> +#include <linux/export.h>
> +#include <linux/jump_label.h>
> +#include <linux/types.h>
> +#include <asm/paravirt.h>
> +
> +struct static_key paravirt_steal_enabled;
> +struct static_key paravirt_steal_rq_enabled;
> +
> +struct pv_time_ops pv_time_ops;
> +EXPORT_SYMBOL_GPL(pv_time_ops);
> 
> 

-- 
Chen Gang

Asianux Corporation