Changeset 82706 in vbox for trunk/src/VBox/VMM/VMMR3

Timestamp:

Jan 10, 2020 5:28:31 AM (5 years ago)

Author:

vboxsync

svn:sync-xref-src-repo-rev:

135632

Message:

VMM/CPUM: Nested SVM: bugref:7243 Clarify comment on allocation of SVM MSRPM and IOPM.

File:

• trunk/src/VBox/VMM/VMMR3/CPUM.cpp (modified) (2 diffs)

trunk/src/VBox/VMM/VMMR3/CPUM.cpp

@@ -1071 +1071 @@
         /*
          * Allocate the MSRPM (MSR Permission bitmap).
+         *
+         * This need not be physically contiguous pages because we use the one from
+         * HMPHYSCPU while executing the nested-guest using hardware-assisted SVM.
+         * This one is just used for caching the bitmap from guest physical memory.
          */
         Assert(!pVCpu->cpum.s.Guest.hwvirt.svm.pvMsrBitmapR3);
@@ -1085 +1089 @@
         /*
          * Allocate the IOPM (IO Permission bitmap).
+         *
+         * This need not be physically contiguous pages because we re-use the ring-0
+         * allocated IOPM while executing the nested-guest using hardware-assisted SVM
+         * because it's identical (we trap all IO accesses).
+         *
+         * This one is just used for caching the IOPM from guest physical memory in
+         * case the guest hypervisor allows direct access to some IO ports.
          */
         Assert(!pVCpu->cpum.s.Guest.hwvirt.svm.pvIoBitmapR3);