Fix SimpleVisor to work on VMWare, stop using KeSaveStateForHibernate and misc. cleanups

SimpleVisor was previously using the presence of *ANY* hypervisor as a
sign that it is already loaded. This breaks if the loaded hypervisor
actually supports nesting and/or isn't SimpleVisor. As such, always try
to enable SimpleVisor -- ShvVmxProbe will fail if we can't, and detect
SimpleVisor explicitly using the Hyper-V Detection Interface (used by
all hypervisors these days).

Second, stop using KeSaveStateForHibernate. While it saved us the need
for two more assembly instructions (str/sldt), it appears to have bugs
around handling of DebugControl, on top of the other bugs we already had
to work around. Instead, just use compiler instrincs to grab the
required state, which is faster anyway.

Move Intel VT-x specific structures into vmx.h instead of shv.h

1 files changed, 10 insertions, 3 deletions

diff --git a/shvvmxhv.c b/shvvmxhv.c
index 20eb4ae..ab8f281 100644
--- a/shvvmxhv.c
+++ b/shvvmxhv.c
@@ -105,7 +105,14 @@ ShvVmxHandleCpuid (
         // Set the Hypervisor Present-bit in RCX, which Intel and AMD have both
         // reserved for this indication.
         //
-        cpu_info[2] |= 0x80000000;
+        cpu_info[2] |= HYPERV_HYPERVISOR_PRESENT_BIT;
+    }
+    else if (VpState->VpRegs->Rax == HYPERV_CPUID_INTERFACE)
+    {
+        //
+        // Return our interface identifier
+        //
+        cpu_info[0] = ' vhS';
     }
 
     //
@@ -262,8 +269,8 @@ ShvVmxEntryHandler (
         // eventually crash the system. Since we know what the original state
         // of the GDTR and IDTR was, simply restore it now.
         //
-        __lgdt(&vpData->HostState.SpecialRegisters.Gdtr.Limit);
-        __lidt(&vpData->HostState.SpecialRegisters.Idtr.Limit);
+        __lgdt(&vpData->SpecialRegisters.Gdtr.Limit);
+        __lidt(&vpData->SpecialRegisters.Idtr.Limit);
 
         //
         // Our DPC routine may have interrupted an arbitrary user process, and