Re: [PATCH v3 0/2] Improve handling of stage 2 aborts without instruction decode

[Christoffer Dall <christoffer.dall@arm.com>]

On Sun, Oct 20, 2019 at 11:25:24AM +0100, Marc Zyngier wrote:
> Hi Christoffer,
> 
> On Fri, 11 Oct 2019 12:07:04 +0100,
> Christoffer Dall <christoffer.dall@arm.com> wrote:
> > 
> > When a guest accesses memory outside the memory slots, KVM usually
> > bounces the access back to userspace with KVM_EXIT_MMIO.  However, on
> > arm/arm64 systems, certain load/store instructions did not provide
> > decoding info for the hypervisor to emulate the instruction, and in this
> > case KVM has rather rudely returned -ENOSYS and printed a not overly
> > helpful error message:
> > 
> >   load/store instruction decoding not implemented
> > 
> > This patch series improves the error message and allows userspace to be
> > notified of this event instead of receiving -ENOSYS, and also allows
> > userspace to ask KVM to inject an external abort to the guest, which it
> > can use for any memory access that it either cannot handle.
> > 
> > One remaining case which this patch set does not address is if the guest
> > accesses an in-kernel emulated device, such as the VGIC, but using a
> > load/store instruction which doesn't provide decode info.  With these
> > patches, this will return to userspace for it to handle, but there's no
> > way for userspace to return the decoding information to KVM and have KVM
> > complete the access to the in-kernel emulated device.  I have no plans
> > to address this limitation.
> 
> You had some pending comments on patch 2, and you seem to indicate
> that you would respin the series. Do you have plans to do so in the
> coming days? I'd like to put that series into -next, but I can either
> wait for your respin, or queue it as it is and apply fixes on top.
> 

I think those for v2 and this is v3 which should address those concerns.
Did I miss something or manage to confuse mysel here?

Thanks,

    Christoffer
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