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7652ac9201
The pinning of sensitive CR0 and CR4 bits caused a boot crash when loading the kvm_intel module on a kernel compiled with CONFIG_PARAVIRT=n. The reason is that the static key which controls the pinning is marked RO after init. The kvm_intel module contains a CR4 write which requires to update the static key entry list. That obviously does not work when the key is in a RO section. With CONFIG_PARAVIRT enabled this does not happen because the CR4 write uses the paravirt indirection and the actual write function is built in. As the key is intended to be immutable after init, move native_write_cr0/4() out of line. While at it consolidate the update of the cr4 shadow variable and store the value right away when the pinning is initialized on a booting CPU. No point in reading it back 20 instructions later. This allows to confine the static key and the pinning variable to cpu/common and allows to mark them static. Fixes:8dbec27a24("x86/asm: Pin sensitive CR0 bits") Fixes:873d50d58f("x86/asm: Pin sensitive CR4 bits") Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Reported-by: Xi Ruoyao <xry111@mengyan1223.wang> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Xi Ruoyao <xry111@mengyan1223.wang> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1907102140340.1758@nanos.tec.linutronix.de
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.