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4346db6e6e
Userspace can directly modify the content of vCPU's CR0, CR3, and CR4 via
KVM_SYNC_X86_SREGS and KVM_SET_SREGS{,2}. Make sure that KVM flushes guest
TLB entries and paging-structure caches if a (partial) guest TLB flush is
architecturally required based on the CRn changes. To keep things simple,
flush whenever KVM resets the MMU context, i.e. if any bits in CR0, CR3,
CR4, or EFER are modified. This is extreme overkill, but stuffing state
from userspace is not such a hot path that preserving guest TLB state is a
priority.
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Link: https://lore.kernel.org/r/20230814222358.707877-3-mhal@rbox.co
[sean: call out that the flushing on MMU context resets is for simplicity]
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 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.