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Message-ID: <1389292336-9292-3-git-send-email-stefano.stabellini@eu.citrix.com>
Date: Thu, 9 Jan 2014 18:32:14 +0000
From: Stefano Stabellini <stefano.stabellini@...citrix.com>
To: <xen-devel@...ts.xensource.com>
CC: <linux-kernel@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>, <konrad.wilk@...cle.com>,
<marc.zyngier@....com>, <will.deacon@....com>,
<Stefano.Stabellini@...citrix.com>, <Ian.Campbell@...rix.com>,
<linux@....linux.org.uk>, <olof@...om.net>, <arnd@...db.de>,
<catalin.marinas@....com>,
Stefano Stabellini <stefano.stabellini@...citrix.com>,
<nico@...aro.org>, <cov@...eaurora.org>
Subject: [PATCH v9 3/5] 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@...citrix.com>
Acked-by: Christopher Covington <cov@...eaurora.org>
Acked-by: Ian Campbell <ian.campbell@...rix.com>
CC: linux@....linux.org.uk
CC: will.deacon@....com
CC: nico@...aro.org
CC: marc.zyngier@....com
CC: cov@...eaurora.org
CC: arnd@...db.de
CC: olof@...om.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/include/asm/paravirt.h | 20 ++++++++++++++++++++
arch/arm/kernel/Makefile | 2 ++
arch/arm/kernel/paravirt.c | 25 +++++++++++++++++++++++++
4 files changed, 67 insertions(+)
create mode 100644 arch/arm/include/asm/paravirt.h
create mode 100644 arch/arm/kernel/paravirt.c
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/include/asm/paravirt.h b/arch/arm/include/asm/paravirt.h
new file mode 100644
index 0000000..8435ff59
--- /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 a30fc9b..34cf9a6 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-$(CONFIG_DEBUG_LL) += debug.o
@@ -97,5 +98,6 @@ ifeq ($(CONFIG_ARM_PSCI),y)
obj-y += psci.o
obj-$(CONFIG_SMP) += psci_smp.o
endif
+obj-$(CONFIG_PARAVIRT) += paravirt.o
extra-y := $(head-y) vmlinux.lds
diff --git a/arch/arm/kernel/paravirt.c b/arch/arm/kernel/paravirt.c
new file mode 100644
index 0000000..53f371e
--- /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@...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);
--
1.7.10.4
--
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