On Thu, Apr 12, 2018 at 11:17:24AM +0100, Robin Murphy wrote: > On 11/04/18 17:54, Marc Zyngier wrote: > >On 11/04/18 16:58, Goel, Sameer wrote: > >>On 3/28/2018 9:00 AM, Marc Zyngier wrote: > >>>A tangential question: can we reliably detect that the SMMU already > >>>has valid mappings, which would indicate that we're in a pretty bad > >>>shape already by the time we set that bit? For all we know, memory > >>>could have been corrupted long before we hit this point, and this > >>>patch barely narrows the window of opportunity. > >> > >>:) Yes that is correct. This only covers the kdump scenario. Trying > >>to get some reliability when booting up the crash kernel. The system > >>is already in a bad state. I don't think that this will happen in a > >>normal scenario. But please point me to the GICv3 change and I'll > >>have a look. > > > >See this: > >https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/tree/drivers/irqchip/irq-gic-v3-its.c?h=irq/irqchip-4.17&id=6eb486b66a3094cdcd68dc39c9df3a29d6a51dd5#n3407 > > The nearest equivalent to that is probably the top-level SMMUEN check that > we already have (see the diff context above). To go beyond that you'd have > to chase the old stream table pointer and scan the whole thing looking for > valid contexts, then potentially walk page tables within those contexts to > check for live translations if you really wanted to be sure. That would be a > hell of a lot of work to do in the boot path.
Yeah, please don't waste time writing a patch to do that! ;) Will _______________________________________________ iommu mailing list email@example.com https://lists.linuxfoundation.org/mailman/listinfo/iommu