[tip:core/smp] virt, sched: Add generic vCPU pinning support

[tip-bot for Juergen Gross]

Commit-ID:  47ae4b05d0fa2f2a998ebaf34d2dcbffca56a9db
Gitweb:     http://git.kernel.org/tip/47ae4b05d0fa2f2a998ebaf34d2dcbffca56a9db
Author:     Juergen Gross <jgross@xxxxxxxx>
AuthorDate: Mon, 29 Aug 2016 08:48:43 +0200
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Mon, 5 Sep 2016 13:52:38 +0200

virt, sched: Add generic vCPU pinning support

Add generic virtualization support for pinning the current vCPU to a
specified physical CPU. As this operation isn't performance critical
(a very limited set of operations like BIOS calls and SMIs is expected
to need this) just add a hypervisor specific indirection.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Douglas_Warzecha@xxxxxxxx
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: akataria@xxxxxxxxxx
Cc: boris.ostrovsky@xxxxxxxxxx
Cc: chrisw@xxxxxxxxxxxx
Cc: david.vrabel@xxxxxxxxxx
Cc: hpa@xxxxxxxxx
Cc: jdelvare@xxxxxxxx
Cc: jeremy@xxxxxxxx
Cc: linux@xxxxxxxxxxxx
Cc: pali.rohar@xxxxxxxxx
Cc: rusty@xxxxxxxxxxxxxxx
Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/1472453327-19050-3-git-send-email-jgross@xxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 MAINTAINERS                       |  1 +
 arch/x86/include/asm/hypervisor.h |  4 ++++
 arch/x86/kernel/cpu/hypervisor.c  | 11 +++++++++++
 include/linux/hypervisor.h        | 17 +++++++++++++++++
 kernel/smp.c                      |  1 +
 kernel/up.c                       |  1 +
 6 files changed, 35 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index db814a8..95151aa 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8845,6 +8845,7 @@ S:	Supported
 F:	Documentation/virtual/paravirt_ops.txt
 F:	arch/*/kernel/paravirt*
 F:	arch/*/include/asm/paravirt.h
+F:	include/linux/hypervisor.h
 
 PARIDE DRIVERS FOR PARALLEL PORT IDE DEVICES
 M:	Tim Waugh <tim@xxxxxxxxxxxx>
diff --git a/arch/x86/include/asm/hypervisor.h b/arch/x86/include/asm/hypervisor.h
index 055ea99..67942b6 100644
--- a/arch/x86/include/asm/hypervisor.h
+++ b/arch/x86/include/asm/hypervisor.h
@@ -43,6 +43,9 @@ struct hypervisor_x86 {
 
 	/* X2APIC detection (run once per boot) */
 	bool		(*x2apic_available)(void);
+
+	/* pin current vcpu to specified physical cpu (run rarely) */
+	void		(*pin_vcpu)(int);
 };
 
 extern const struct hypervisor_x86 *x86_hyper;
@@ -56,6 +59,7 @@ extern const struct hypervisor_x86 x86_hyper_kvm;
 extern void init_hypervisor(struct cpuinfo_x86 *c);
 extern void init_hypervisor_platform(void);
 extern bool hypervisor_x2apic_available(void);
+extern void hypervisor_pin_vcpu(int cpu);
 #else
 static inline void init_hypervisor(struct cpuinfo_x86 *c) { }
 static inline void init_hypervisor_platform(void) { }
diff --git a/arch/x86/kernel/cpu/hypervisor.c b/arch/x86/kernel/cpu/hypervisor.c
index 27e4665..35691a6 100644
--- a/arch/x86/kernel/cpu/hypervisor.c
+++ b/arch/x86/kernel/cpu/hypervisor.c
@@ -86,3 +86,14 @@ bool __init hypervisor_x2apic_available(void)
 	       x86_hyper->x2apic_available &&
 	       x86_hyper->x2apic_available();
 }
+
+void hypervisor_pin_vcpu(int cpu)
+{
+	if (!x86_hyper)
+		return;
+
+	if (x86_hyper->pin_vcpu)
+		x86_hyper->pin_vcpu(cpu);
+	else
+		WARN_ONCE(1, "vcpu pinning requested but not supported!\n");
+}
diff --git a/include/linux/hypervisor.h b/include/linux/hypervisor.h
new file mode 100644
index 0000000..3fa5ef2
--- /dev/null
+++ b/include/linux/hypervisor.h
@@ -0,0 +1,17 @@
+#ifndef __LINUX_HYPEVISOR_H
+#define __LINUX_HYPEVISOR_H
+
+/*
+ *	Generic Hypervisor support
+ *		Juergen Gross <jgross@xxxxxxxx>
+ */
+
+#ifdef CONFIG_HYPERVISOR_GUEST
+#include <asm/hypervisor.h>
+#else
+static inline void hypervisor_pin_vcpu(int cpu)
+{
+}
+#endif
+
+#endif /* __LINUX_HYPEVISOR_H */
diff --git a/kernel/smp.c b/kernel/smp.c
index 3aa642d..4274ca5 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -14,6 +14,7 @@
 #include <linux/smp.h>
 #include <linux/cpu.h>
 #include <linux/sched.h>
+#include <linux/hypervisor.h>
 
 #include "smpboot.h"
 
diff --git a/kernel/up.c b/kernel/up.c
index 1760bf3..3ccee2b 100644
--- a/kernel/up.c
+++ b/kernel/up.c
@@ -6,6 +6,7 @@
 #include <linux/kernel.h>
 #include <linux/export.h>
 #include <linux/smp.h>
+#include <linux/hypervisor.h>
 
 int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
 				int wait)