arm64: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops

Introduce CONFIG_PARAVIRT and PARAVIRT_TIME_ACCOUNTING on ARM64.
Necessary duplication of paravirt.h and paravirt.c with 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: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 871f21783866d5fdb1557ec56e5f13b602ba331a..987ae39cc471b9faf42f450cd2c3baf8e68ea7ad 100644 (file)
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -556,6 +556,25 @@ config SECCOMP
          and the task is only allowed to execute a few safe syscalls
          defined by each seccomp mode.
 
+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
@@ -564,6 +583,7 @@ config XEN
        bool "Xen guest support on ARM64"
        depends on ARM64 && OF
        select SWIOTLB_XEN
+       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 (file)
index 0000000..fd5f428
--- /dev/null
+++ b/arch/arm64/include/asm/paravirt.h
@@ -0,0 +1,20 @@
+#ifndef _ASM_ARM64_PARAVIRT_H
+#define _ASM_ARM64_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/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 474691f8b13ab893cf403b8c1737a91aeff87bc0..ca9fbe1d7bd974d8a13e72675ae03592e1f08b37 100644 (file)
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -41,6 +41,7 @@ arm64-obj-$(CONFIG_EFI)                       += efi.o efi-entry.stub.o
 arm64-obj-$(CONFIG_PCI)                        += pci.o
 arm64-obj-$(CONFIG_ARMV8_DEPRECATED)   += armv8_deprecated.o
 arm64-obj-$(CONFIG_ACPI)               += acpi.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 (file)
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 <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);