Hi,
I realised I made a confusing mistake in my last reply; clarification below.
On Mon, Aug 01, 2016 at 06:26:54PM +0100, Mark Rutland wrote:
> On Mon, Aug 01, 2016 at 05:57:50PM +0100, Julien Grall wrote:
> > however we only need one TLBI instruction (assuming there is
> > no superpage shattering) per-batch rather than one per-entry in this
> > case.
>
> I got Cc'd to a reply without the original patch context, so I'm not
> sure what the case is here. I'm not exactly sure what you mean by
> "per-batch".
>
> Assuming that you've (only) changed the permissions (i.e. the AP bits
> and XN bits) of a number of stage-2 leaf entries, you need either:
[...]
> * Per entry, a TLBI IPAS2LE1IS
>
> e.g.
>
> for_each_entry(x)
> modify_ap_bits(x);
> dsb(ishst);
> tlbi(ipas2le1is);
> dsb(ish);
Here I was trying to have the bare minimum barriers necessary, but in focussing
on that I failed to add the required loop to have a TLBI per entry.
The above should have been:
for_each_entry(x)
modify_ap_bits(x);
dsb(ishst);
for_each_entry(x)
tlbi(ipas2le1is, x);
dsb(ish);
Assuming the necessary bit fiddling for the TLBI to affect the IPA of x, with
the right VMID, etc.
Thanks,
Mark.
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