* [question]: __gnttab_map_grant_ref() and iommu
@ 2012-04-04 2:14 Mukesh Rathor
2012-04-04 7:28 ` Ian Campbell
0 siblings, 1 reply; 2+ messages in thread
From: Mukesh Rathor @ 2012-04-04 2:14 UTC (permalink / raw)
To: Xen-devel@lists.xensource.com
Cc: Ian Campbell, stefano.stabellini@eu.citrix.com
Hi,
I'm not able to figure why __gnttab_map_grant_ref() does PV iommu
mappings for GNTMAP_host_map. Should it not check for GNTMAP_device_map
and do for those only?
thanks,
Mukesh
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [question]: __gnttab_map_grant_ref() and iommu
2012-04-04 2:14 [question]: __gnttab_map_grant_ref() and iommu Mukesh Rathor
@ 2012-04-04 7:28 ` Ian Campbell
0 siblings, 0 replies; 2+ messages in thread
From: Ian Campbell @ 2012-04-04 7:28 UTC (permalink / raw)
To: Mukesh Rathor; +Cc: Xen-devel@lists.xensource.com, Stefano Stabellini
On Wed, 2012-04-04 at 03:14 +0100, Mukesh Rathor wrote:
> I'm not able to figure why __gnttab_map_grant_ref() does PV iommu
> mappings for GNTMAP_host_map. Should it not check for GNTMAP_device_map
> and do for those only?
I don't know but perhaps it is because when the backend maps a foreign
page there is a reasonably high chance that it is eventually going to
end up passing that page to a hardware device (e.g. a physical NIC or
disk controller) for DMA and therefore the mapping must be reflected in
the IOMMU.
Ian.
^ permalink raw reply [flat|nested] 2+ messages in thread
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