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Check guest physical address against its maximum, which depends on the guest MAXPHYADDR. If the guest's physical address exceeds the maximum (i.e. has reserved bits set), inject a guest page fault with PFERR_RSVD_MASK set. This has to be done both in the EPT violation and page fault paths, as there are complications in both cases with respect to the computation of the correct error code. For EPT violations, unfortunately the only possibility is to emulate, because the access type in the exit qualification might refer to an access to a paging structure, rather than to the access performed by the program. Trapping page faults instead is needed in order to correct the error code, but the access type can be obtained from the original error code and passed to gva_to_gpa. The corrections required in the error code are subtle. For example, imagine that a PTE for a supervisor page has a reserved bit set. On a supervisor-mode access, the EPT violation path would trigger. However, on a user-mode access, the processor will not notice the reserved bit and not include PFERR_RSVD_MASK in the error code. Co-developed-by: Mohammed Gamal <mgamal@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20200710154811.418214-8-mgamal@redhat.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.