WIP Add freeze code

ntoskrnl/ke/amd64/ipi.c

@@ -18,6 +18,61 @@ static PKIPI_BROADCAST_WORKER KiIpiBroadcastWorkerTable[] =
     NULL, // IPI_FREEZE
 };
 
+PKPRCB KiFreezeOwner;
+
+VOID
+FreezeOtherProcessors(
+    VOID)
+{
+    PKPRCB CurrentPrcb = KeGetCurrentPrcb();
+
+    /* Try to acquire the freeze owner */
+    while (InterlockedCOmpareExchangePointer(&KiFreezeOwner, CurrentPrcb, NULL))
+    {
+        /* Someone else was faster. We expect an NMI to freeze any time.
+           Spin here until we can grab the lock */
+        while (KiFreezeOwner != NULL)
+        {
+            KeMemoryBarrier();
+        }
+    }
+
+    /* We are the owner now */
+    CurrentPrcb->IpiFrozen = IPI_FROZEN_STATE_OWNER;
+
+    /* Loop all processors */
+    for (ULONG i = 0; i < KeNumberProcessors; i++)
+    {
+        PKPRCB TargetPrcb = KiProcessorBlock[i];
+        if (TargetPrcb != CurrentPrcb)
+        {
+            ASSERT(TargetPrcb->IpiFrozen == IPI_FROZEN_STATE_RUNNING);
+
+            /* Set the target to frozen */
+            TargetPrcb->IpiFrozen = IPI_FROZEN_STATE_TARGET_FREEZE;
+        }
+    }
+
+    /* Send the NMI */
+    HalpSendNMI(KeActiveProcessors & ~CurrentPrcb->SetMember);
+
+    /* Wait for all targets to be frozen */
+    for (ULONG i = 0; i < KeNumberProcessors; i++)
+    {
+        PKPRCB TargetPrcb = KiProcessorBlock[i];
+        if (TargetPrcb != CurrentPrcb)
+        {
+            /* Wait for the target to be frozen */
+            while (TargetPrcb->IpiFrozen != IPI_FROZEN_STATE_FROZEN)
+            {
+                KeMemoryBarrier();
+            }
+        }
+    }
+
+    /* All targets are frozen, we can continue */
+}
+
 VOID
 FASTCALL
 KiIpiInterruptHandler(