[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [RFC 12/19] xen/passthrough: iommu_deassign_device_dt: By default reassign device to nobody
On Thu, 2014-07-03 at 14:01 +0100, Julien Grall wrote: > On 07/03/2014 01:53 PM, Ian Campbell wrote: > > On Thu, 2014-07-03 at 13:07 +0100, Julien Grall wrote: > >>>> If Xen reassigns the device to "nobody", it may receive some > >>>> global/context > >>>> fault because the transaction has failed (indeed the context has been > >>>> marked invalid). > >>> > >>> Can you describe here what happen in this case (I presume Xen tears down > >>> the iommu to quiesce them somehow?) > >> > >> The SMMU drivers will mark the different Context Bank, S2CR, SMR as > >> invalid. If the device is attempt to access the memory then, we will > >> receive an interrupt in Xen. > >> > >> Actually it's only happen once, if the device is still enabled when the > >> domain is shutdown. > > > > My concern was with getting a storm of such interrupts after this point. > > If it only happens once and any subsequent ones are damped by some means > > then great. > > I guess, it can happen with a buggy device trying to access memory > alone. But I don't think we should care about this case. Ideally such a device wouldn't be able to DoS the rest of the system. Does the SMMU not have a bit to say: deny all MMIO from this context without raising an exception? Ian. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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