Re: [Xen-devel] [PATCH 4/4] xen/arm: gic: Relax barrier when sending an SGI

[Julien Grall <julien.grall@xxxxxxx>]

On 10/24/18 2:32 PM, Andrii Anisov wrote:
> Hello Julien,
Hi Andrii,

> On 23.10.18 21:17, Julien Grall wrote:
> > diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
> > index 0108e9603c..077b941b79 100644
> > --- a/xen/arch/arm/gic.c
> > +++ b/xen/arch/arm/gic.c
> > @@ -300,12 +300,6 @@ void send_SGI_mask(const cpumask_t *cpumask, enum gic_sgi 
> > sgi)
> >    {
> >        ASSERT(sgi < 16); /* There are only 16 SGIs */
> >    
> > -   /*
> > -    * Ensure that stores to Normal memory are visible to the other CPUs
> > -    * before issuing the IPI.
> > -    * Matches the read barrier in do_sgi.
> > -    */
> > -    dsb(sy);
> Here you remove the comment you've just added within this patch series,
> and the same below.
> Wouldn't it better to reorder patches, first relax the barrier, then
> ensure ordering between read of INTACK and shared data?
patch #1 and #2 should be backported. This patch is technically not a 
bug fix but a relaxation. So I am not comfortable to suggest backporting 
it up to Xen 4.9. Hence the ordering of the series.
Cheers,

--
Julien Grall

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