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, 46 insertions, 0 deletions

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 61dff55f137e..a012d70d9eff 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -2642,6 +2642,27 @@ static int kvm_vcpu_ioctl_set_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
         return 0;
 }
 
+static int kvm_vcpu_ioctl_get_lapic(struct kvm_vcpu *vcpu,
+                                    struct kvm_lapic_state *s)
+{
+        vcpu_load(vcpu);
+        memcpy(s->regs, vcpu->apic->regs, sizeof *s);
+        vcpu_put(vcpu);
+
+        return 0;
+}
+
+static int kvm_vcpu_ioctl_set_lapic(struct kvm_vcpu *vcpu,
+                                    struct kvm_lapic_state *s)
+{
+        vcpu_load(vcpu);
+        memcpy(vcpu->apic->regs, s->regs, sizeof *s);
+        kvm_apic_post_state_restore(vcpu);
+        vcpu_put(vcpu);
+
+        return 0;
+}
+
 static long kvm_vcpu_ioctl(struct file *filp,
                            unsigned int ioctl, unsigned long arg)
 {
@@ -2811,6 +2832,31 @@ static long kvm_vcpu_ioctl(struct file *filp,
                 r = 0;
                 break;
         }
+        case KVM_GET_LAPIC: {
+                struct kvm_lapic_state lapic;
+
+                memset(&lapic, 0, sizeof lapic);
+                r = kvm_vcpu_ioctl_get_lapic(vcpu, &lapic);
+                if (r)
+                        goto out;
+                r = -EFAULT;
+                if (copy_to_user(argp, &lapic, sizeof lapic))
+                        goto out;
+                r = 0;
+                break;
+        }
+        case KVM_SET_LAPIC: {
+                struct kvm_lapic_state lapic;
+
+                r = -EFAULT;
+                if (copy_from_user(&lapic, argp, sizeof lapic))
+                        goto out;
+                r = kvm_vcpu_ioctl_set_lapic(vcpu, &lapic);;
+                if (r)
+                        goto out;
+                r = 0;
+                break;
+        }
         default:
                 ;
         }