ff3dc6521f
Shared Virtual Memory(SVM) is based on a collective set of hardware features detected at runtime. There are requirements for matching CPU and IOMMU capabilities. The current code checks CPU and IOMMU feature set for SVM support but the result is never stored nor used. Therefore, SVM can still be used even when these checks failed. The consequences can be: 1. CPU uses 5-level paging mode for virtual address of 57 bits, but IOMMU can only support 4-level paging mode with 48 bits address for DMA. 2. 1GB page size is used by CPU but IOMMU does not support it. VT-d unrecoverable faults may be generated. The best solution to fix these problems is to prevent them in the first place. This patch consolidates code for checking PASID, CPU vs. IOMMU paging mode compatibility, as well as provides specific error messages for each failed checks. On sane hardware configurations, these error message shall never appear in kernel log. Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com> Reviewed-by: Eric Auger <eric.auger@redhat.com> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.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.