Re: [PATCH 3/3] KVM: arm64: Skip break phase when we have FEAT_BBM level 2

[Oliver Upton]

Hey Will,

On Thu, Jun 08, 2023 at 06:21:13PM +0100, Will Deacon wrote:
> > IIRC, Colton was testing largely with permission relaxation, and had
> > forward progress issues b.c. the stale TLB entry was never invalidated
> > in response to a permission fault.
> 
> Would the series at:
> 
> https://lore.kernel.org/r/5d8e1f752051173d2d1b5c3e14b54eb3506ed3ef.1684892404.git-series.apopple@xxxxxxxxxx
> 
> help with that?

Heh, that's a rather interesting patch :)

I don't think it is directly related to the problem Colton encounters,
though the symptoms are similar. This crops up when KVM uses a stricter
permission set than the primary MMU, like lazy X for deferred I$
maintenance and write-protection for dirty logging. KVM policy led to
the stale TLB entry, so KVM is the one that needs to initiate the
invalidation.

-- 
Thanks,
Oliver