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VT-d shares the EPT tables as the second level translation tables. For the IOMMUs that don't support page-walk coherecy, cpu cache should be flushed for the IOMMU EPT entries that are modified. For the current implementation, EPT tables for translating from GPA to HPA for EPT/IOMMU are not modified after VM is created, so cpu cache invlidation is done once per VM before starting execution of VM. However, this may be changed, runtime EPT modification is possible. When cpu cache of EPT entries is invalidated when modification, there is no need invalidate cpu cache globally per VM. This patch exports iommu_flush_cache for EPT entry cache invlidation operations. - IOMMUs share the same copy of EPT table, cpu cache should be flushed if any of the IOMMU active doesn't support page-walk coherency. - In the context of ACRN, GPA to HPA mapping relationship is not changed after VM created, skip flushing iotlb to avoid potential performance penalty. Tracked-On: #3607 Signed-off-by: Binbin Wu <binbin.wu@intel.com> Reviewed-by: Anthony Xu <anthony.xu@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/