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authorStefano Stabellini <stefano.stabellini@eu.citrix.com>2015-11-23 10:32:57 +0000
committerDavid Vrabel <david.vrabel@citrix.com>2015-12-21 14:40:54 +0000
commit02c2433b3aa6b57313c261c9811bbbe49528101c (patch)
tree8081453d55ffc7b54560cd99e069a9890ee7ea68
parent1fe7c4ef88bd32e039f5f4126537c3f20c340414 (diff)
arm: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops
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>
-rw-r--r--arch/arm/Kconfig20
-rw-r--r--arch/arm/include/asm/paravirt.h20
-rw-r--r--arch/arm/kernel/Makefile1
-rw-r--r--arch/arm/kernel/paravirt.c25
4 files changed, 66 insertions, 0 deletions
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 34e1569a11ee..1ab9b98d4c6c 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -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.
diff --git a/arch/arm/include/asm/paravirt.h b/arch/arm/include/asm/paravirt.h
new file mode 100644
index 000000000000..8435ff591386
--- /dev/null
+++ b/arch/arm/include/asm/paravirt.h
@@ -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
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index af9e59bf3831..3e6e93725ca7 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -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
diff --git a/arch/arm/kernel/paravirt.c b/arch/arm/kernel/paravirt.c
new file mode 100644
index 000000000000..53f371ed4568
--- /dev/null
+++ b/arch/arm/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 <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);