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Currently, IOMMU invalidations and device-IOTLB invalidations using AMD IOMMU fall back to full address-space invalidation if more than a single page need to be flushed. Full flushes are especially inefficient when the IOMMU is virtualized by a hypervisor, since it requires the hypervisor to synchronize the entire address-space. AMD IOMMUs allow to provide a mask to perform page-specific invalidations for multiple pages that match the address. The mask is encoded as part of the address, and the first zero bit in the address (in bits [51:12]) indicates the mask size. Use this hardware feature to perform selective IOMMU and IOTLB flushes. Combine the logic between both for better code reuse. The IOMMU invalidations passed a smoke-test. The device IOTLB invalidations are untested. Cc: Joerg Roedel <joro@8bytes.org> Cc: Will Deacon <will@kernel.org> Cc: Jiajun Cao <caojiajun@vmware.com> Cc: iommu@lists.linux-foundation.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Nadav Amit <namit@vmware.com> Link: https://lore.kernel.org/r/20210323210619.513069-1-namit@vmware.com Signed-off-by: Joerg Roedel <jroedel@suse.de>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.