Changeset 74543 in vbox for trunk

Timestamp:

Oct 1, 2018 7:36:57 AM (6 years ago)

Author:

vboxsync

Message:

VMM/IEM: Nested VMX: bugref:9180 Comment regarding caching of VMCS related data structures.

File:

trunk/src/VBox/VMM/VMMAll/IEMAllCImplVmxInstr.cpp.h

-              r74542
+              r74543
+    }
+    /*
+     * We are allowed to cache VMCS related data structures (such as I/O bitmaps, MSR bitmaps)
+     * while entering VMX non-root mode. We do some of this while checking VM-execution
+     * controls. The guest hypervisor should not make assumptions and is cannot expect
+     * predictable behavior if changes to these structures are made in guest memory after
+     * executing VMX non-root mode. As far as VirtualBox is concerned, the guest cannot modify
+     * them anyway as we cache them in host memory. We are trade memory for speed here.
+     *
+     * See Intel spec. 24.11.4 "Software Access to Related Structures".
+     */
     rc = iemVmxVmentryCheckExecCtls(pVCpu, pszInstr);
     if (RT_SUCCESS(rc))

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