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80eb5fea3c
Pull powerpc Spectre-RSB fixes from Michael Ellerman: "We failed to activate the mitigation for Spectre-RSB (Return Stack Buffer, aka. ret2spec) on context switch, on CPUs prior to Power9 DD2.3. That allows a process to poison the RSB (called Link Stack on Power CPUs) and possibly misdirect speculative execution of another process. If the victim process can be induced to execute a leak gadget then it may be possible to extract information from the victim via a side channel. The fix is to correctly activate the link stack flush mitigation on all CPUs that have any mitigation of Spectre v2 in userspace enabled. There's a second commit which adds a link stack flush in the KVM guest exit path. A leak via that path has not been demonstrated, but we believe it's at least theoretically possible. This is the fix for CVE-2019-18660" * tag 'powerpc-spectre-rsb' of /home/torvalds/Downloads/powerpc-CVE-2019-18660.bundle: KVM: PPC: Book3S HV: Flush link stack on guest exit to host kernel powerpc/book3s64: Fix link stack flush on context switch
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.