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RE: [PATCH 1/3] xen/arm: Reduce redundant clear root pages when teardown p2m


  • To: Julien Grall <julien@xxxxxxx>, Michal Orzel <michal.orzel@xxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
  • From: Henry Wang <Henry.Wang@xxxxxxx>
  • Date: Fri, 27 Jan 2023 11:04:23 +0000
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  • Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>, Bertrand Marquis <Bertrand.Marquis@xxxxxxx>, Wei Chen <Wei.Chen@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
  • Delivery-date: Fri, 27 Jan 2023 11:04:47 +0000
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  • Thread-topic: [PATCH 1/3] xen/arm: Reduce redundant clear root pages when teardown p2m

Hi Michal and Julien,

Apologies for the late response.

> -----Original Message-----
> >> +    PROGRESS(p2m_root):
> >> +        /*
> >> +         * We are about to free the intermediate page-tables, so clear the
> >> +         * root to prevent any walk to use them.
> > The comment from here...
> >> +         * The domain will not be scheduled anymore, so in theory we
> should
> >> +         * not need to flush the TLBs. Do it for safety purpose.
> >> +         * Note that all the devices have already been de-assigned. So we
> don't
> >> +         * need to flush the IOMMU TLB here.
> >> +         */
> > to here does not make a lot of sense in this place and should be moved to
> p2m_clear_root_pages
> > where a user can see the call to p2m_force_tlb_flush_sync.
> 
> +1

I will move this code comment block to the place that you suggested in v2.

> 
> > Apart from that:
> > Reviewed-by: Michal Orzel <michal.orzel@xxxxxxx>
> 
> Acked-by: Julien Grall <jgrall@xxxxxxxxxx>

Thanks to both of you. I will keep these two tags with the fix about the above
in-code comment position.

Kind regards,
Henry

> 
> Cheers,
> 
> --
> Julien Grall

 


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