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Issue description: ----------------- Machine Check Error on Page Size Change Instruction fetch may cause machine check error if page size and memory type was changed without invalidation on some processors[1][2]. Malicious guest kernel could trigger this issue. This issue applies to both primary page table and extended page tables (EPT), however the primary page table is controlled by hypervisor only. This patch mitigates the situation in EPT. Mitigation details: ------------------ Implement non-execute huge pages in EPT. This patch series clears the execute permission (bit 2) in the EPT entries for large pages. When EPT violation is triggered by guest instruction fetch, hypervisor converts the large page to smaller 4 KB pages and restore the execute permission, and then re-execute the guest instruction. The current patch turns on the mitigation by default. The follow-up patches will conditionally turn on/off the feature per processor model. [1] Refer to erratum KBL002 in "7th Generation Intel Processor Family and 8th Generation Intel Processor Family for U Quad Core Platforms Specification Update" https://www.intel.com/content/dam/www/public/us/en/documents/specification-updates/7th-gen-core-family-spec-update.pdf [2] Refer to erratum SKL002 in "6th Generation Intel Processor Family Specification Update" https://www.intel.com/content/www/us/en/products/docs/processors/core/desktop-6th-gen-core-family-spec-update.html Tracked-On: #4120 Signed-off-by: Binbin Wu <binbin.wu@intel.com> Reviewed-by: Eddie Dong <eddie.dong@intel.com>
ACRN Hypervisor ############### The open source `Project ACRN`_ defines a device hypervisor reference stack and an architecture for running multiple software subsystems, managed securely, on a consolidated system by means of a virtual machine manager. It also defines a reference framework implementation for virtual device emulation, called the "ACRN Device Model". The ACRN Hypervisor is a Type 1 reference hypervisor stack, running directly on the bare-metal hardware, and is suitable for a variety of IoT and embedded device solutions. The ACRN hypervisor addresses the gap that currently exists between datacenter hypervisors, and hard partitioning hypervisors. The ACRN hypervisor architecture partitions the system into different functional domains, with carefully selected guest OS sharing optimizations for IoT and embedded devices. You can find out more about Project ACRN on the `Project ACRN documentation`_ website. .. _`Project ACRN`: https://projectacrn.org .. _`ACRN Hypervisor`: https://github.com/projectacrn/acrn-hypervisor .. _`Project ACRN documentation`: https://projectacrn.github.io/