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Date: Tue, 10 Mar 2015 17:57:56 +0100
From: Andrew Jones <drjones@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 2/5] target-arm: enable get_rw_prot to take
	simple AP
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: QEMU Developers <qemu-devel@nongnu.org>

On Tue, Mar 10, 2015 at 04:41:45PM +0000, Peter Maydell wrote:
> On 10 March 2015 at 16:32, Andrew Jones <drjones@redhat.com> wrote:
> > On Tue, Mar 10, 2015 at 03:22:55PM +0000, Peter Maydell wrote:
> >> I'm confused. Even if we're using the simple-permissions
> >> model, the ap parameter is still AP[2:0]. Shouldn't this
> >> switch be for cases 0, 2, 4, 6 ?
> >
> > Depends on how we choose to implement the callers. Currently
> > I only require the caller to send in 2 bits for the simple
> > model. If we want to require them to send in 3, then we'll
> > need to shift a zero in for the lpae caller, rather than
> > shift a zero out for the v6 caller.
> 
> You have to have the callers just pass in AP[2:0], unless
> you want them to have to duplicate the "are we using the
> simple permissions model?" condition to figure out whether
> to shift the argument around, which doesn't seem very
> sensible.
>

The v6 caller is the only one that could be either-or, and it
already checked regime_sctlr(env, mmu_idx) & SCTLR_AFE, as it
wanted to see if it cared about the access flag anyway. I
suspect any new callers that could be either-or would do the
same.

drew