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arm: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops

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Introduce CONFIG_PARAVIRT and PARAVIRT_TIME_ACCOUNTING on ARM.

The only paravirt interface supported is pv_time_ops.steal_clock, so no
runtime pvops patching needed.

This allows us to make use of steal_account_process_tick for stolen
ticks accounting.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Christopher Covington <cov@codeaurora.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Russell King <linux@arm.linux.org.uk>
This commit is contained in:
Stefano Stabellini 2015-11-23 10:32:57 +00:00 committed by David Vrabel
parent 1fe7c4ef88
commit 02c2433b3a
4 changed files with 66 additions and 0 deletions
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20
arch/arm/Kconfig
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@ -1800,6 +1800,25 @@ config SWIOTLB
config IOMMU_HELPER
def_bool SWIOTLB
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
@ -1813,6 +1832,7 @@ config XEN
select ARCH_DMA_ADDR_T_64BIT
select ARM_PSCI
select SWIOTLB_XEN
select PARAVIRT
help
Say Y if you want to run Linux in a Virtual Machine on Xen on ARM.

20
arch/arm/include/asm/paravirt.h Normal file
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@ -0,0 +1,20 @@
#ifndef _ASM_ARM_PARAVIRT_H
#define _ASM_ARM_PARAVIRT_H
#ifdef CONFIG_PARAVIRT
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
#endif

1
arch/arm/kernel/Makefile
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@ -81,6 +81,7 @@ obj-$(CONFIG_VDSO) += vdso.o
ifneq ($(CONFIG_ARCH_EBSA110),y)
obj-y += io.o
endif
obj-$(CONFIG_PARAVIRT) += paravirt.o
head-y := head$(MMUEXT).o
obj-$(CONFIG_DEBUG_LL) += debug.o

25
arch/arm/kernel/paravirt.c Normal file
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@ -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 <stefano.stabellini@eu.citrix.com>
*/
#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);