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e88cfd50b6
Advertise support for LKGS (load into IA32_KERNEL_GS_BASE) to userspace if the instruction is supported by the underlying CPU. LKGS is introduced with FRED to completely eliminate the need to swapgs explicilty. It behaves like the MOV to GS instruction except that it loads the base address into the IA32_KERNEL_GS_BASE MSR instead of the GS segment’s descriptor cache, which is exactly what Linux kernel does to load a user level GS base. Thus there is no need to SWAPGS away from the kernel GS base. LKGS is an independent CPU feature that works correctly in a KVM guest without requiring explicit enablement. Signed-off-by: Xin Li (Intel) <xin@zytor.com> Link: https://lore.kernel.org/r/20250626173521.2301088-1-xin@zytor.com Signed-off-by: Sean Christopherson <seanjc@google.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 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.