KVM: Implement NotifyLongSpinWait HYPER-V hypercall

Windows issues this hypercall after guest was spinning on a spinlock
for too many iterations.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Vadim Rozenfeld <vrozenfe@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 552be51e4d84..9f72a443455b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1564,6 +1564,7 @@ int kvm_dev_ioctl_check_extension(long ext)
         case KVM_CAP_VCPU_EVENTS:
         case KVM_CAP_HYPERV:
         case KVM_CAP_HYPERV_VAPIC:
+        case KVM_CAP_HYPERV_SPIN:
                 r = 1;
                 break;
         case KVM_CAP_COALESCED_MMIO:
@@ -3827,7 +3828,14 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
 
         trace_kvm_hv_hypercall(code, fast, rep_cnt, rep_idx, ingpa, outgpa);
 
-        res = HV_STATUS_INVALID_HYPERCALL_CODE;
+        switch (code) {
+        case HV_X64_HV_NOTIFY_LONG_SPIN_WAIT:
+                kvm_vcpu_on_spin(vcpu);
+                break;
+        default:
+                res = HV_STATUS_INVALID_HYPERCALL_CODE;
+                break;
+        }
 
         ret = res | (((u64)rep_done & 0xfff) << 32);
         if (longmode) {