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Subject[PATCH v8 3/6] arm: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops
Date
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>
CC: linux@arm.linux.org.uk
CC: will.deacon@arm.com
CC: nico@linaro.org
CC: marc.zyngier@arm.com
CC: cov@codeaurora.org
CC: arnd@arndb.de
CC: olof@lixom.net

---

Changes in v7:
- ifdef CONFIG_PARAVIRT the content of paravirt.h.

Changes in v3:
- improve commit description and Kconfig help text;
- no need to initialize pv_time_ops;
- add PARAVIRT_TIME_ACCOUNTING.
---
arch/arm/Kconfig | 20 ++++++++++++++++++++
arch/arm/kernel/Makefile | 1 +
2 files changed, 21 insertions(+)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index c1f1a7e..d6c3ba1 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1874,6 +1874,25 @@ 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
@@ -1885,6 +1904,7 @@ config XEN
depends on !GENERIC_ATOMIC64
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.

diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index a30fc9b..bcd2b38 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -87,6 +87,7 @@ obj-$(CONFIG_ARM_CPU_TOPOLOGY) += topology.o
ifneq ($(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
--
1.7.10.4


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