KVM: in-kernel LAPIC save and restore support

This patch adds a new vcpu-based IOCTL to save and restore the local
apic registers for a single vcpu. The kernel only copies the apic page as
a whole, extraction of registers is left to userspace side. On restore, the
APIC timer is restarted from the initial count, this introduces a little
delay, but works fine.

Signed-off-by: Yaozu (Eddie) Dong <eddie.dong@intel.com>
Signed-off-by: Qing He <qing.he@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/drivers/kvm/lapic.c b/drivers/kvm/lapic.c
index 4b5c77d8900d..df636bf19798 100644
--- a/drivers/kvm/lapic.c
+++ b/drivers/kvm/lapic.c
@@ -931,3 +931,16 @@ int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu)
         apic_clear_irr(vector, apic);
         return vector;
 }
+
+void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu)
+{
+        struct kvm_lapic *apic = vcpu->apic;
+
+        apic->base_address = vcpu->apic_base &
+                             MSR_IA32_APICBASE_BASE;
+        apic_set_reg(apic, APIC_LVR, APIC_VERSION);
+        apic_update_ppr(apic);
+        hrtimer_cancel(&apic->timer.dev);
+        update_divide_count(apic);
+        start_apic_timer(apic);
+}