On Thu, Aug 20, 2020 at 2:59 PM Alexander Graf <graf@xxxxxxxxxx> wrote:
> Do we really need to do all of this dance of differentiating in kernel
> space between an exit that's there because user space asked for the exit
> and an MSR access that would just generate a #GP?
>
> At the end of the day, user space *knows* which MSRs it asked to
> receive. It can filter for them super easily.
If no one else has an opinion, I can let this go. :-)
However, to make the right decision in kvm_emulate_{rdmsr,wrmsr}
(without the unfortunate before and after checks that Aaron added),
kvm_{get,set}_msr should at least distinguish between "permission
denied" and "raise #GP," so I can provide a deny list without asking
for userspace exits on #GP.
