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With PTW disabled system, bit _PAGE_DIRTY is a HW bit for page writing. However with PTW enabled system, bit _PAGE_WRITE is also a "HW bit" for page writing, because hardware synchronizes _PAGE_WRITE to _PAGE_DIRTY automatically. Previously, _PAGE_WRITE is treated as a SW bit to record the page writeable attribute for the fast page fault handling in the secondary MMU, however with PTW enabled machine, this bit is used by HW already (so setting it will silence the TLB modify exception). Here define KVM_PAGE_WRITEABLE with the SW bit _PAGE_MODIFIED, so that it can work on both PTW disabled and enabled machines. And for HW write bits, both _PAGE_DIRTY and _PAGE_WRITE are set or clear together. Cc: stable@vger.kernel.org Signed-off-by: Bibo Mao <maobibo@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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.