Re: [PATCH v3 1/2] kvm: x86: Allow userspace to handle emulation errors

[Sean Christopherson <seanjc@google.com>]

Please wait at least a day between versions to give everyone a chance to review
the latest information and digest other folks' comments.  Even a single day is
a bit too frequent in most cases, especially for a series where people are
actively commenting on the changes, as is the case here.  I.e. give the current
conversation a chance to run its course before spawning a new thread.  Exceptions
are few and far between, e.g. if you completely botched something and there's no
point in having people review the current versions.

Also, please include a cover letter with a synopsis of the delta between versions.
Without that, reviewers have no idea what's different in v1 vs. v2 vs. v3 vs. vN,
which increases the burden on reviewers.  The delta information is especially
helpful if other reviewers join the conversation at a later point.

On Wed, Apr 21, 2021, Aaron Lewis wrote:
> Add a fallback mechanism to the in-kernel instruction emulator that
> allows userspace the opportunity to process an instruction the emulator
> was unable to.  When the in-kernel instruction emulator fails to process
> an instruction it will either inject a #UD into the guest or exit to
> userspace with exit reason KVM_INTERNAL_ERROR.  This is because it does
> not know how to proceed in an appropriate manner.  This feature lets
> userspace get involved to see if it can figure out a better path
> forward.
> 
> Signed-off-by: Aaron Lewis <aaronlewis@google.com>