c72ceafbd1
filemap users like guest_memfd may use page cache pages to allocate/manage memory that is only intended to be accessed by guests via hardware protections like encryption. Writes to memory of this sort in common paths like truncation may cause unexpected behavior such as writing garbage instead of zeros when attempting to zero pages, or worse, triggering hardware protections that are considered fatal as far as the kernel is concerned. Introduce a new address_space flag, AS_INACCESSIBLE, and use this initially to prevent zero'ing of pages during truncation, with the understanding that it is up to the owner of the mapping to handle this specially if needed. This is admittedly a rather blunt solution, but it seems like there are no other places that should take into account the flag to keep its promise. Link: https://lore.kernel.org/lkml/ZR9LYhpxTaTk6PJX@google.com/ Cc: Matthew Wilcox <willy@infradead.org> Suggested-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Michael Roth <michael.roth@amd.com> Message-ID: <20240329212444.395559-5-michael.roth@amd.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> 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 reStructuredText 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.