Re: [PATCH 0/5] KVM: arm/arm64: fix some races and allow userspace to set MPIDR

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On Wed, Mar 08, 2017 at 09:27:12AM -0800, Christoffer Dall wrote:
> Hi Drew,
> 
> On Mon, Feb 27, 2017 at 06:54:59PM +0100, Andrew Jones wrote:
> > This series fixes four races. Two are easy to produce with a
> > kvm-unit-test test[1], but the other two would be quite hard. I
> > didn't even try to produce those. The two hard to produce races are
> > addressed by changing vcpu->arch.pause and vcpu->arch.power_off to
> > vcpu requests. The two easy to produce races are addressed in two
> > different ways: the first takes advantage of power_off having been
> > changed to a vcpu request, the second caches vcpu MPIDRs in order
> > to avoid extracting them from sys_regs. When introducing the MPIDR
> > cache we also introduce a new feature (userspace settable MPIDRs).
> > 
> > Support for userspace settable MPIDRs was already posted once[2],
> > but rejected due to not having a use case. We have one now, which
> > is to satisfy QEMU's need for the MPDIR information very early,
> > before vcpu-init has even run. While the original posting author
> > wasn't me, I've taken authorship now, as I've changed the patch
> > substantially. If anybody disagrees with that, then feel free to
> > suggest alternatives. The QEMU counterpart has been posted[3].
> > 
> > This series is based on Radim's recent posting[4] that improves
> > the vcpu-request framework. I've tested the series on a couple
> > AArch64 platforms and compile-tested the arm bits.
> 
> So as we discussed during lunch today, it would be awesome if you could
> split this up into a series that fixes the identified races and a
> separate series for the introduction of supporting setting the MPIDR
> from user space.

Will do. Thanks for reviewing!

drew

> 
> Thanks a lot!
> -Christoffer
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