Re: [Xen-devel] [PATCH 3/4] xen: arm: add barrier before sev in smp_spin_table_cpu_up

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Mon, 2014-03-17 at 14:43 +0000, Julien Grall wrote:
> On 03/17/2014 02:39 PM, Ian Campbell wrote:
> >>> The ARMv8 ARM recommends that sev() is usually accompanied by a dsb(), the
> >>> only other uses are in the v7 spinlock code which includes a dsb() 
> >>> already.
> >>
> >> Would it be better to add dsb in the sev() macro?
> > 
> > ARM32 has a dsb_sev macro, maybe we should do the same for ARM64.
> 
> Do we really need to rename the macro?

I think so.

> From what I understand, most of
> the time sev => dsb before. I think we can hide it in sev() macro.

These macros are thin shims around the underlying instructions, having
them do other stuff as well would be potentially misleading.

The current macro has one callsight, I think we can live with the
churn...

Ian.



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