VMMR0

Timestamp:

Jul 19, 2013 1:04:47 PM (12 years ago)

Author:

vboxsync

Message:

VMM/HMVMXR0: Minor clarification.

File:

trunk/src/VBox/VMM/VMMR0/HMVMXR0.cpp

-              r47247
+              r47254
      * bird: This isn't quite as simple.  VT-x and VBox(!) requires the DPL for SS to be the the same as CPL.  In 64-bit mode it
      *       is possible (int/trap/xxx injects does this when switching rings) to load SS with a NULL selector and RPL=CPL.
      *       The Attr.u = X86DESCATTR_UNUSABLE works fine as long as nobody uses ring-1 or ring-2.  VT-x seems to set the DPL
      *       correctly in the attributes even when the unusable bit is set, we need to preseve the DPL or we get invalid guest
      *       state trouble.  Try bs2-cpu-hidden-regs-1.
+     *       The Attr.u = X86DESCATTR_UNUSABLE works fine as long as nobody uses ring-1 or ring-2.  VT-x updates the DPL
+     *       correctly in the attributes of SS even when the unusable bit is set, we need to preseve the DPL or we get invalid
+     *       guest state trouble.  Try bs2-cpu-hidden-regs-1.
      */
     if (pSelReg->Attr.u & X86DESCATTR_UNUSABLE)

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