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Subject[PATCH v3 4/6] KVM-GST: KVM Steal time registration
Date
Register steal time within KVM. Everytime we sample the steal time
information, we update a local variable that tells what was the
last time read. We then account the difference.

Signed-off-by: Glauber Costa <glommer@redhat.com>
CC: Rik van Riel <riel@redhat.com>
CC: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
CC: Peter Zijlstra <peterz@infradead.org>
CC: Avi Kivity <avi@redhat.com>
---
arch/x86/kernel/kvm.c | 43 +++++++++++++++++++++++++++++++++++++++++++
arch/x86/kernel/kvmclock.c | 2 ++
2 files changed, 45 insertions(+), 0 deletions(-)
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 33c07b0..ea49217 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -58,6 +58,7 @@ struct kvm_para_state {

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_SHARED_ALIGNED(struct kvm_steal_time, steal_time);

static struct kvm_para_state *kvm_para_state(void)
{
@@ -483,24 +484,46 @@ static struct notifier_block kvm_pv_reboot_nb = {
.notifier_call = kvm_pv_reboot_notify,
};

+static int kvm_register_steal_time(void)
+{
+ int cpu = smp_processor_id();
+ int low, high, ret;
+ struct kvm_steal_time *st = &per_cpu(steal_time, cpu);
+
+ if (!hypervisor_steal_time)
+ return 0;
+
+ memset(st, 0, sizeof(*st));
+
+ low = (int)__pa(st) | 1;
+ high = ((u64)__pa(st) >> 32);
+ ret = wrmsr_safe(MSR_KVM_STEAL_TIME, low, high);
+ printk(KERN_INFO "kvm-stealtime: cpu %d, msr %x:%x\n",
+ cpu, high, low);
+ return ret;
+}
+
#ifdef CONFIG_SMP
static void __init kvm_smp_prepare_boot_cpu(void)
{
#ifdef CONFIG_KVM_CLOCK
WARN_ON(kvm_register_clock("primary cpu clock"));
#endif
+ WARN_ON(kvm_register_steal_time());
kvm_guest_cpu_init();
native_smp_prepare_boot_cpu();
}

static void __cpuinit kvm_guest_cpu_online(void *dummy)
{
+ WARN_ON(kvm_register_steal_time());
kvm_guest_cpu_init();
}

static void kvm_guest_cpu_offline(void *dummy)
{
kvm_pv_disable_apf(NULL);
+ wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
apf_task_wake_all();
}

@@ -534,6 +557,23 @@ static void __init kvm_apf_trap_init(void)
set_intr_gate(14, &async_page_fault);
}

+static u64 kvm_account_steal_time(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 ((src->version & 1) || (version != src->version));
+
+ return steal;
+}
+
void __init kvm_guest_init(void)
{
int i;
@@ -548,6 +588,9 @@ void __init kvm_guest_init(void)
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))
+ hypervisor_steal_time = kvm_account_steal_time;
+
#ifdef CONFIG_SMP
smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
register_cpu_notifier(&kvm_cpu_notifier);
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
index f98d3ea..dcb6a67 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -164,6 +164,7 @@ static void __cpuinit kvm_setup_secondary_clock(void)
static void kvm_crash_shutdown(struct pt_regs *regs)
{
native_write_msr(msr_kvm_system_time, 0, 0);
+ wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
native_machine_crash_shutdown(regs);
}
#endif
@@ -171,6 +172,7 @@ static void kvm_crash_shutdown(struct pt_regs *regs)
static void kvm_shutdown(void)
{
native_write_msr(msr_kvm_system_time, 0, 0);
+ wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
native_machine_shutdown();
}

--
1.7.2.3


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