Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [patch 33/37] iommu/arm-smmu-v3: Use msi_get_virq() | Date | Mon, 29 Nov 2021 15:42:14 +0100 |
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On Mon, Nov 29 2021 at 13:13, Robin Murphy wrote: > On 2021-11-29 10:55, Will Deacon wrote: >>> - } >>> + smmu->evtq.q.irq = msi_get_virq(dev, EVTQ_MSI_INDEX); >>> + smmu->gerr_irq = msi_get_virq(dev, GERROR_MSI_INDEX); >>> + smmu->priq.q.irq = msi_get_virq(dev, PRIQ_MSI_INDEX); >> >> Prviously, if retrieval of the MSI failed then we'd fall back to wired >> interrupts. Now, I think we'll clobber the interrupt with 0 instead. Can >> we make the assignments to smmu->*irq here conditional on the MSI being >> valid, please? > > I was just looking at that too, but reached the conclusion that it's > probably OK, since consumption of this value later is gated on > ARM_SMMU_FEAT_PRI, so the fact that it changes from 0 to an error value > in the absence of PRI should make no practical difference.
It's actually 0 when the vector cannot be found.
> If we don't have MSIs at all, we'd presumably still fail earlier > either at the dev->msi_domain check or upon trying to allocate the > vectors, so we'll still fall back to any previously-set wired values > before getting here. The only remaining case is if we've > *successfully* allocated the expected number of vectors yet are then > somehow unable to retrieve one or more of them - presumably the system > has to be massively borked for that to happen, at which point do we > really want to bother trying to reason about anything?
Probably not. At that point something is going to explode sooner than later in colorful ways.
Thanks,
tglx
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