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KarimAllah Ahmed
d28b387fb7
[ Based on a patch from Ashok Raj <[email protected]> ] Add direct access to MSR_IA32_SPEC_CTRL for guests. This is needed for guests that will only mitigate Spectre V2 through IBRS+IBPB and will not be using a retpoline+IBPB based approach. To avoid the overhead of saving and restoring the MSR_IA32_SPEC_CTRL for guests that do not actually use the MSR, only start saving and restoring when a non-zero is written to it. No attempt is made to handle STIBP here, intentionally. Filtering STIBP may be added in a future patch, which may require trapping all writes if we don't want to pass it through directly to the guest. [dwmw2: Clean up CPUID bits, save/restore manually, handle reset] Signed-off-by: KarimAllah Ahmed <[email protected]> Signed-off-by: David Woodhouse <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Reviewed-by: Darren Kenny <[email protected]> Reviewed-by: Konrad Rzeszutek Wilk <[email protected]> Reviewed-by: Jim Mattson <[email protected]> Cc: Andrea Arcangeli <[email protected]> Cc: Andi Kleen <[email protected]> Cc: Jun Nakajima <[email protected]> Cc: [email protected] Cc: Dave Hansen <[email protected]> Cc: Tim Chen <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Asit Mallick <[email protected]> Cc: Arjan Van De Ven <[email protected]> Cc: Greg KH <[email protected]> Cc: Paolo Bonzini <[email protected]> Cc: Dan Williams <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Ashok Raj <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.