Changeset 48673 in vbox for trunk/src/VBox/VMM/VMMAll

Timestamp:

Sep 25, 2013 8:24:06 AM (11 years ago)

Author:

vboxsync

Message:

VMM/CPUMAllA.asm: Revert r89225, caller already saves/restores CR0. Added a comment explain this.

File:

• trunk/src/VBox/VMM/VMMAll/CPUMAllA.asm (modified) (2 diffs)

trunk/src/VBox/VMM/VMMAll/CPUMAllA.asm

@@ -38 +38 @@
 
 BEGINCODE
-
 
 ;;
@@ -171 +170 @@
 %endif
 hlfpua_finished_switch:
-%ifndef IN_RING3 ; IN_RC or IN_RING0
+
+    ; Load new CR0 value.
+    ; IN_RING0 the caller saves/restores CR0 anyway, so avoid the extra CR0 write.
+    ; Currently the only caller in ring-0 is CPUMR0LoadGuestFPU()->CPUMHandleLazyFPU().
+    ;; @todo Optimize the many unconditional CR0 writes.
+%ifdef IN_RC
     mov     cr0, xCX                            ; load the new cr0 flags.
 %endif