On Sat, Feb 21, 2015 at 03:56:17PM -0600, Rob Herring wrote: > On Thu, Feb 19, 2015 at 1:03 PM, Christoffer Dall > <christoffer.dall@xxxxxxxxxx> wrote: > > On Thu, Feb 19, 2015 at 12:23:15PM -0600, Rob Herring wrote: > >> On Tue, Jan 27, 2015 at 1:03 AM, Pranavkumar Sawargaonkar > >> <psawargaonkar@xxxxxxx> wrote: > >> > In APM X-Gene, GIC register space is 64K aligned while the sizes mentioned > >> > in the dt are 4K aligned. This breaks KVM when kernel is built with 64K page > >> > size due to size alignment checking in vgic driver for VCPU Control and > >> > VCPU register. > >> > > >> > This patch corrects the sizes to be inline with the hardware spec. > >> > >> This does not make sense. The GIC regions are still only 4 or 8KB and > >> the h/w description should reflect that. For implementations using > >> gic-400 and the addressing decode trick, the rest of the register > >> range is also not safe to access given it is multiple mapped. Also, > >> this wastes virtual space, but I guess we don't care on 64-bit. > >> > >> KVM should be fixed to only check base address alignment. Size > >> alignment does not matter (if it does, then you need to fix all > >> register blocks). > >> > > It matters if you want to ensure that the 64K page you are assigning to > > a guest for the GIC virtual CPU interface contains only GIC virtual CPU > > mappings, and not other random stuff that the guest is not allowed to > > touch. > > Good point. > > > How else should this be enforced? > > Rely on correct h/w design? You'll have to repeat this every time you > want to do pass-thru of a device. > > What do you do if 64K mapping is not supported? Fallback to emulation > of the CPU interface? Agree with Peter on these two points. > > Are there other DTSs that need to be fixed? > Not sure really, AMD Seattle works with 64K pages IIRC. Thanks, -Christoffer -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
