Changeset 71966 in vbox for trunk/include

Timestamp:

Apr 23, 2018 4:40:51 AM (7 years ago)

Author:

vboxsync

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

122224

Message:

VMM/HMSVMAll: Some comments on the nuances of the VMCB caching with hardware-assisted SVM execution of nested-guests.

File:

• trunk/include/VBox/vmm/hm_svm.h (modified) (1 diff)

trunk/include/VBox/vmm/hm_svm.h

@@ -1019 +1019 @@
  * SVM R0 code for hardware-assisted SVM execution of a nested-guest.
  *
+ * A VMCB field needs to be cached when it needs to be modified for execution using
+ * hardware-assisted SVM and any of the following are true:
+ *   - If the original field needs to be inspected during execution of the
+ *     nested-guest or #VMEXIT processing.
+ *   - If the field is written back to memory on #VMEXIT by the physical CPU.
+ *
+ * A VMCB field needs to be restored only when the field is written back to
+ * memory on #VMEXIT by the physical CPU and thus would be visible to the guest.
+ *
  * @remarks Please update hmR3InfoSvmNstGstVmcbCache() when changes are made to
  *          this structure.