7cd138db5c
Drop the pre-computed last_nonleaf_level, which is arguably wrong and at best confusing. Per the comment: Can have large pages at levels 2..last_nonleaf_level-1. the intent of the variable would appear to be to track what levels can _legally_ have large pages, but that intent doesn't align with reality. The computed value will be wrong for 5-level paging, or if 1gb pages are not supported. The flawed code is not a problem in practice, because except for 32-bit PSE paging, bit 7 is reserved if large pages aren't supported at the level. Take advantage of this invariant and simply omit the level magic math for 64-bit page tables (including PAE). For 32-bit paging (non-PAE), the adjustments are needed purely because bit 7 is ignored if PSE=0. Retain that logic as is, but make is_last_gpte() unique per PTTYPE so that the PSE check is avoided for PAE and EPT paging. In the spirit of avoiding branches, bump the "last nonleaf level" for 32-bit PSE paging by adding the PSE bit itself. Note, bit 7 is ignored or has other meaning in CR3/EPTP, but despite FNAME(walk_addr_generic) briefly grabbing CR3/EPTP in "pte", they are not PTEs and will blow up all the other gpte helpers. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210622175739.3610207-51-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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.