[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [PATCH v5 20/22] xen/arm: ITS: Map ITS translation space


On 27/07/2015 04:12, vijay.kilari@xxxxxxxxx wrote:
From: Vijaya Kumar K <Vijaya.Kumar@xxxxxxxxxxxxxxxxxx>

ITS translation space contains GITS_TRANSLATOR register


which is written by device to raise LPI. This space needs
to mapped to every domain address space for all physical
ITS available,so that device can access GITS_TRANSLATOR


register using SMMU.

Marc pointed me today that if the processor is writing into GITS_TRANSLATER it may be able to deadlock the system.

Reading more closely the spec (8.1.3 IHI0069A), there is undefined behavior when writing to this register with wrong access size.

Currently the page table are shared between the processor and the SMMU, so that means that a domain will be able to deadlock the processor and therefore the whole platform.

So we should never expose GITS_TRANSLATER into the processor page table. Which means unsharing some parts if not all of the page tables between the processor and the SMMU.

While it's not required for this series, you don't support guest, this would be mandatory to fix it before any usage of the vITS by a guest.


Julien Grall

Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.