KVM: x86: Add ioctl for KVM_KVMCLOCK_CTRL

Now that we have a flag that will tell the guest it was suspended, create an
interface for that communication using a KVM ioctl.

Signed-off-by: Eric B Munson <emunson@mgebm.net>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 511031dcb9cc..99b738028fc0 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2147,6 +2147,7 @@ int kvm_dev_ioctl_check_extension(long ext)
         case KVM_CAP_ASYNC_PF:
         case KVM_CAP_GET_TSC_KHZ:
         case KVM_CAP_PCI_2_3:
+        case KVM_CAP_KVMCLOCK_CTRL:
                 r = 1;
                 break;
         case KVM_CAP_COALESCED_MMIO:
@@ -2597,6 +2598,23 @@ static int kvm_vcpu_ioctl_x86_set_xcrs(struct kvm_vcpu *vcpu,
         return r;
 }
 
+/*
+ * kvm_set_guest_paused() indicates to the guest kernel that it has been
+ * stopped by the hypervisor.  This function will be called from the host only.
+ * EINVAL is returned when the host attempts to set the flag for a guest that
+ * does not support pv clocks.
+ */
+static int kvm_set_guest_paused(struct kvm_vcpu *vcpu)
+{
+        struct pvclock_vcpu_time_info *src = &vcpu->arch.hv_clock;
+        if (!vcpu->arch.time_page)
+                return -EINVAL;
+        src->flags |= PVCLOCK_GUEST_STOPPED;
+        mark_page_dirty(vcpu->kvm, vcpu->arch.time >> PAGE_SHIFT);
+        kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
+        return 0;
+}
+
 long kvm_arch_vcpu_ioctl(struct file *filp,
                          unsigned int ioctl, unsigned long arg)
 {
@@ -2873,6 +2891,10 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
                 r = vcpu->arch.virtual_tsc_khz;
                 goto out;
         }
+        case KVM_KVMCLOCK_CTRL: {
+                r = kvm_set_guest_paused(vcpu);
+                goto out;
+        }
         default:
                 r = -EINVAL;
         }