On 30.07.14 18:21, Paolo Bonzini wrote:
Il 30/07/2014 15:27, Alexander Graf ha scritto:
Now that we have properly split load/store instruction emulation and generic
instruction emulation, we can move the generic one from kvm.ko to kvm-pr.ko
on book3s_64.
This reduces the attack surface and amount of code loaded on HV KVM kernels.
Can emulation races happen on HV KVM like you can have on x86?
Basically one CPU writes to MMIO while the other patches instructions so
that basically anything can end up in the hands of the emulator? On PPC
it may even happen simply because of a missing icache invalidation, I
think, since it doesn't support self-modifying code without explicit
invalidation.
Yes, this is perfectly possible. As of my last patch set we will never
enter the generic emulator for HV KVM, so that race is moot (we just
inject a PROGRAM interrupt into the guest). With this patch even the
code to emulate these bits doesn't exist in the kernel anymore if you
don't modprobe kvm-pr.ko.
Alex
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