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When updating guest CPUID entries to emulate runtime behavior, e.g. when the guest enables a CR4-based feature that is tied to a CPUID flag, also update the vCPU's cpu_caps accordingly. This will allow replacing all usage of guest_cpuid_has() with guest_cpu_cap_has(). Note, this relies on kvm_set_cpuid() taking a snapshot of cpu_caps before invoking kvm_update_cpuid_runtime(), i.e. when KVM is updating CPUID entries that *may* become the vCPU's CPUID, so that unwinding to the old cpu_caps is possible if userspace tries to set bogus CPUID information. Note #2, none of the features in question use guest_cpu_cap_has() at this time, i.e. aside from settings bits in cpu_caps, this is a glorified nop. Cc: Yang Weijiang <weijiang.yang@intel.com> Cc: Robert Hoo <robert.hoo.linux@gmail.com> Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com> Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com> Link: https://lore.kernel.org/r/20241128013424.4096668-49-seanjc@google.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.