Merge branch 'core-smp-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull core SMP updates from Ingo Molnar:
 "Two main change is generic vCPU pinning and physical CPU SMP-call
  support, for Xen to be able to perform certain calls on specific
  physical CPUs - by Juergen Gross"

* 'core-smp-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  smp: Allocate smp_call_on_cpu() workqueue on stack too
  hwmon: Use smp_call_on_cpu() for dell-smm i8k
  dcdbas: Make use of smp_call_on_cpu()
  xen: Add xen_pin_vcpu() to support calling functions on a dedicated pCPU
  smp: Add function to execute a function synchronously on a CPU
  virt, sched: Add generic vCPU pinning support
  xen: Sync xen header

3 files changed, 55 insertions, 0 deletions

diff --git a/arch/x86/include/asm/hypervisor.h b/arch/x86/include/asm/hypervisor.h
index 055ea9941dd5..67942b6ad4b7 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 27e46658ebe3..35691a6b0d32 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/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index b86ebb1a9a7f..bc9aaba01a22 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1925,6 +1925,45 @@ static void xen_set_cpu_features(struct cpuinfo_x86 *c)
 	}
 }
 
+static void xen_pin_vcpu(int cpu)
+{
+	static bool disable_pinning;
+	struct sched_pin_override pin_override;
+	int ret;
+
+	if (disable_pinning)
+		return;
+
+	pin_override.pcpu = cpu;
+	ret = HYPERVISOR_sched_op(SCHEDOP_pin_override, &pin_override);
+
+	/* Ignore errors when removing override. */
+	if (cpu < 0)
+		return;
+
+	switch (ret) {
+	case -ENOSYS:
+		pr_warn("Unable to pin on physical cpu %d. In case of problems consider vcpu pinning.\n",
+			cpu);
+		disable_pinning = true;
+		break;
+	case -EPERM:
+		WARN(1, "Trying to pin vcpu without having privilege to do so\n");
+		disable_pinning = true;
+		break;
+	case -EINVAL:
+	case -EBUSY:
+		pr_warn("Physical cpu %d not available for pinning. Check Xen cpu configuration.\n",
+			cpu);
+		break;
+	case 0:
+		break;
+	default:
+		WARN(1, "rc %d while trying to pin vcpu\n", ret);
+		disable_pinning = true;
+	}
+}
+
 const struct hypervisor_x86 x86_hyper_xen = {
 	.name			= "Xen",
 	.detect			= xen_platform,
@@ -1933,6 +1972,7 @@ const struct hypervisor_x86 x86_hyper_xen = {
 #endif
 	.x2apic_available	= xen_x2apic_para_available,
 	.set_cpu_features       = xen_set_cpu_features,
+	.pin_vcpu               = xen_pin_vcpu,
 };
 EXPORT_SYMBOL(x86_hyper_xen);