On Tue, Nov 13, 2018 at 12:56 PM Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> wrote: > > > Just one point: > > Have you considered the option to add this property per (TBT?) device? > > No. ;-) > > You mean that one device uses security levels and another IOMMU? I don't > think it is possible without having some sort of table in the IOMMU > driver telling which devices it needs identity map and which not. Also > not sure what would be the benefit? For performance, of course. If some devices are considered safe (maybe a list communicated by platform firmware), the kernel may decide to configure them to passthrough the IOMMU (I think I remember there is such an option, but maybe I'm wrong.) > > If the kernel may decide to enable/disable the IOMMU or AST per device, maybe > > it should be on this level. > > Or maybe the IOMMU decision isn't going to change (it's system-wide) and the AST > > decision will be communicated per device by a new sysfs attribute anyway, if > > needed? > > Not sure what you mean by "AST"? The IOMMU decision is pretty much > system-wide. Sorry, I meant ATS, Address Translation Service, mentioned in patch 3 in this series, and possibly be enabled for some devices for performance, as mentioned there. So if needed, this will be another attribute, and definitely per-device, isn't it?
