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Date: Tue, 17 Oct 2017 14:17:06 +0200
From: Cornelia Huck <cohuck@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v1 0/2] s390x/tcg: LAP support using
 immediate TLB invalidation
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To: David Hildenbrand <david@redhat.com>
Cc: qemu-devel@nongnu.org, qemu-s390x@nongnu.org, Thomas Huth <thuth@redhat.com>, Richard Henderson <rth@twiddle.net>, Alexander Graf <agraf@suse.de>, Peter Maydell <peter.maydell@linaro.org>

On Mon, 16 Oct 2017 22:23:56 +0200
David Hildenbrand <david@redhat.com> wrote:

> Details about Low-Address Protection can be found in description of
> patch 1 and 2. It is basically a subpage protection of the first two
> pages of every address space (for which it is enabled).
> 
> We can achieve this by simply directly invalidating the TLB entry and
> therefore forcing every write accesses onto these two pages into the slow
> path.
> 
> With this patch, I can boot Linux just fine (which uses LAP). This also
> makes all related kvm-unit-tests that we have pass.
> 
> 
> RFC -> v1:
> - fix LAP range check (Thomas)
> - SIGP fix got picked up
> 
> Based on: https://github.com/cohuck/qemu.git s390-next
> Available on: https://github.com/dhildenb/qemu.git s390x_lap
> 
> 
> David Hildenbrand (2):
>   accel/tcg: allow to invalidate a write TLB entry immediately
>   s390x/tcg: low-address protection support
> 
>  accel/tcg/cputlb.c           |  5 ++-
>  accel/tcg/softmmu_template.h |  4 +-
>  include/exec/cpu-all.h       |  3 ++
>  target/s390x/excp_helper.c   |  3 +-
>  target/s390x/mem_helper.c    |  8 ----
>  target/s390x/mmu_helper.c    | 94 +++++++++++++++++++++++++++-----------------
>  6 files changed, 69 insertions(+), 48 deletions(-)
> 

As the oom was not reproducible (and seems to be only a problem of the
machine being run with barely enough memory), I'm inclined to queue
this to s390-next after I got some acks/r-bs for patch 1.