Isolating guest code and data using multiple nested page tables

A non-transitory computer readable medium comprising instructions to be executed in a host including one or more processors and host physical memory to carry out a method of isolating secure guest code to be executed in a guest that is configured in the host by a virtualization software, said method comprising:

• creating first page tables, which are used for guest physical to host physical address translations, that provide mappings to a first protected region of host physical memory where the secure guest code has been loaded;
• creating second page tables, which are used for guest physical to host physical address translations, that provide mappings to a second protected region of the host physical memory that is distinct from the first protected region of the host physical memory;
• storing third page tables, which are used for guest virtual to guest physical address translations, in the first protected region;
• storing fourth page tables, which are used for guest virtual to guest physical address translations, in the second protected region;
• and
• when execution is switched from a non-secure guest code, which is loaded into the second protected region, to the secure guest code, changing a first pointer value from one that points to the fourth page tables to one that points to the third page tables so that the third page tables are accessed for guest virtual to guest physical address translations, and changing a second pointer value from one that points to the second page tables to one that points to the first page tables so that the first page tables are accessed for guest physical to host physical address translations.

A host including one or more processors and host physical memory, and having a virtualization software installed therein to carry out a method of isolating secure guest code to be executed in a guest configured by the virtualization software, said method comprising:

• creating first page tables, which are used for guest physical to host physical address translations, that provide mappings to a first protected region of host physical memory where the secure guest code has been loaded;
• creating second page tables, which are used for guest physical to host physical address translations, that provide mappings to a second protected region of the host physical memory that is distinct from the first protected region of the host physical memory;
• storing third page tables, which are used for guest virtual to guest physical address translations, in the first protected region;
• storing fourth page tables, which are used for guest virtual to guest physical address translations, in the second protected region;
• and
• when execution is switched from a non-secure guest code, which is loaded into the second protected region, to the secure guest code, changing a first pointer value from one that points to the fourth page tables to one that points to the third page tables so that the third page tables are accessed for guest virtual to guest physical address translations, and changing a second pointer value from one that points to the second page tables to one that points to the first page tables so that the first page tables are accessed for guest physical to host physical address translations.