a8ac499bb6
Drop the requirement that a pfn be backed by a refcounted, compound or or ZONE_DEVICE, struct page, and instead rely solely on the host page tables to identify huge pages. The PageCompound() check is a remnant of an old implementation that identified (well, attempt to identify) huge pages without walking the host page tables. The ZONE_DEVICE check was added as an exception to the PageCompound() requirement. In other words, neither check is actually a hard requirement, if the primary has a pfn backed with a huge page, then KVM can back the pfn with a huge page regardless of the backing store. Dropping the @pfn parameter will also allow KVM to query the max host mapping level without having to first get the pfn, which is advantageous for use outside of the page fault path where KVM wants to take action if and only if a page can be mapped huge, i.e. avoids the pfn lookup for gfns that can't be backed with a huge page. Cc: Mingwei Zhang <mizhang@google.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Mingwei Zhang <mizhang@google.com> Message-Id: <20220715232107.3775620-2-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.