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6e6ec58485
Hold the mmu_lock for write for the entire duration of allocating and initializing an MMU's roots. This ensures there are MMU pages available and thus prevents root allocations from failing. That in turn fixes a bug where KVM would fail to free valid PAE roots if a one of the later roots failed to allocate. Add a comment to make_mmu_pages_available() to call out that the limit is a soft limit, e.g. KVM will temporarily exceed the threshold if a page fault allocates multiple shadow pages and there was only one page "available". Note, KVM _still_ leaks the PAE roots if the guest PDPTR checks fail. This will be addressed in a future commit. Cc: Ben Gardon <bgardon@google.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210305011101.3597423-7-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.