commit d910f5c1064d7ff09c31b0191564f9f99e210f91
author Glauber Costa <glommer@redhat.com> Mon Jul 11 15:28:19 2011 -0400
committer Avi Kivity <avi@redhat.com> Sun Jul 24 11:49:36 2011 +0300
tree fcc977e4b0b6f1fc9dbdcc485753a7422147a40e
parent 095c0aa83e52d6c3dd7168610746703921f570af

KVM guest: KVM Steal time registration

This patch implements the kvm bits of the steal time infrastructure.
The most important part of it, is the steal time clock. It is an
continuous clock that shows the accumulated amount of steal time
since vcpu creation. It is supposed to survive cpu offlining/onlining.

[marcelo: fix build with CONFIG_KVM_GUEST=n]

Signed-off-by: Glauber Costa <glommer@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Tested-by: Eric B Munson <emunson@mgebm.net>
CC: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
CC: Peter Zijlstra <peterz@infradead.org>
CC: Avi Kivity <avi@redhat.com>
CC: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

arch/x86/kernel/kvm.c

diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 33c07b0..a9c2116 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -51,6 +51,15 @@
 
 early_param("no-kvmapf", parse_no_kvmapf);
 
+static int steal_acc = 1;
+static int parse_no_stealacc(char *arg)
+{
+        steal_acc = 0;
+        return 0;
+}
+
+early_param("no-steal-acc", parse_no_stealacc);
+
 struct kvm_para_state {
 	u8 mmu_queue[MMU_QUEUE_SIZE];
 	int mmu_queue_len;
@@ -58,6 +67,8 @@
 
 static DEFINE_PER_CPU(struct kvm_para_state, para_state);
 static DEFINE_PER_CPU(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
+static DEFINE_PER_CPU(struct kvm_steal_time, steal_time) __aligned(64);
+static int has_steal_clock = 0;
 
 static struct kvm_para_state *kvm_para_state(void)
 {
@@ -441,6 +452,21 @@
 #endif
 }
 
+static void kvm_register_steal_time(void)
+{
+	int cpu = smp_processor_id();
+	struct kvm_steal_time *st = &per_cpu(steal_time, cpu);
+
+	if (!has_steal_clock)
+		return;
+
+	memset(st, 0, sizeof(*st));
+
+	wrmsrl(MSR_KVM_STEAL_TIME, (__pa(st) | KVM_MSR_ENABLED));
+	printk(KERN_INFO "kvm-stealtime: cpu %d, msr %lx\n",
+		cpu, __pa(st));
+}
+
 void __cpuinit kvm_guest_cpu_init(void)
 {
 	if (!kvm_para_available())
@@ -457,6 +483,9 @@
 		printk(KERN_INFO"KVM setup async PF for cpu %d\n",
 		       smp_processor_id());
 	}
+
+	if (has_steal_clock)
+		kvm_register_steal_time();
 }
 
 static void kvm_pv_disable_apf(void *unused)
@@ -483,6 +512,31 @@
 	.notifier_call = kvm_pv_reboot_notify,
 };
 
+static u64 kvm_steal_clock(int cpu)
+{
+	u64 steal;
+	struct kvm_steal_time *src;
+	int version;
+
+	src = &per_cpu(steal_time, cpu);
+	do {
+		version = src->version;
+		rmb();
+		steal = src->steal;
+		rmb();
+	} while ((version & 1) || (version != src->version));
+
+	return steal;
+}
+
+void kvm_disable_steal_time(void)
+{
+	if (!has_steal_clock)
+		return;
+
+	wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
+}
+
 #ifdef CONFIG_SMP
 static void __init kvm_smp_prepare_boot_cpu(void)
 {
@@ -500,6 +554,7 @@
 
 static void kvm_guest_cpu_offline(void *dummy)
 {
+	kvm_disable_steal_time();
 	kvm_pv_disable_apf(NULL);
 	apf_task_wake_all();
 }
@@ -548,6 +603,11 @@
 	if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF))
 		x86_init.irqs.trap_init = kvm_apf_trap_init;
 
+	if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
+		has_steal_clock = 1;
+		pv_time_ops.steal_clock = kvm_steal_clock;
+	}
+
 #ifdef CONFIG_SMP
 	smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
 	register_cpu_notifier(&kvm_cpu_notifier);
@@ -555,3 +615,15 @@
 	kvm_guest_cpu_init();
 #endif
 }
+
+static __init int activate_jump_labels(void)
+{
+	if (has_steal_clock) {
+		jump_label_inc(&paravirt_steal_enabled);
+		if (steal_acc)
+			jump_label_inc(&paravirt_steal_rq_enabled);
+	}
+
+	return 0;
+}
+arch_initcall(activate_jump_labels);