Messages in this thread | | | Date | Wed, 7 Sep 2022 17:58:53 +0800 | Subject | Re: [PATCH v2 1/2] iova: Remove some magazine pointer NULL checks | From | Ethan Zhao <> |
| |
John,
在 2022/9/7 16:46, John Garry 写道: > On 06/09/2022 19:25, Robin Murphy wrote: >>> >>> Caveat: on the chance that the IOVA domain init fails due to the >>> rcache init failing, then, if there were another device in the group >>> which probes later, its probe would be ok as the start_pfn is set. >>> Not Good. >> >> Yeah, there's a lot not to like about iommu_dma_init_domain() - I've >> been banking on it all getting cleaned up when I get to refactoring >> that area of probing (remember the issue you reported years ago with >> PCI groups being built in the wrong order? All related...), but in >> fact since the cookie management got pulled into core code, we can >> probably tie the IOVA domain setup to that right now without much >> other involvement. That could be a cheap win, so I'll give it a go soon. > > ok, great. > > On a related topic, another thing to consider is that errors in IOVA > domain init are not handled gracefully in terms of how we deal with > the device probe and setting dma mapping ops, ref > iommu_setup_dma_ops(). I assume you know all this. > >> >>> - vdpa just fails to create the domain in vduse_domain_create() >>> >>>> That makes a fair amount of sense, but does mean that we're missing >>>> the equivalent in iova_rcache_insert() for it to actually work. Or >>>> we just remove it and tighten up the documentation to say that's >>>> not valid >>> >>> I'd be more inclined to remove it. I would rather remove fathpath >>> checks as much as possible and have robust error handling in the >>> domain init. >>> >>> Afterall I do have the "remove check" craze going. >> >> Sure, like I say I'm happy to be consistent either way. If I do end >> up reinstating such a check I think I'd prefer to have it explicit in >> {alloc,free}_iova_fast() anyway, rather than buried in internal >> implementation details. > > I'm not sure what you would like to see now, if anything. > > I could just remove the iovad->rcache check in iova_rcache_get(). > It's pretty useless (on its own) since we don't have the same check on > the "insert" path. > > Or also add this: > > diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c > index 0d6d8edf782d..e8f0b8f47f45 100644 > --- a/drivers/iommu/dma-iommu.c > +++ b/drivers/iommu/dma-iommu.c > @@ -578,6 +578,12 @@ static int iommu_dma_init_domain(struct > iommu_domain *domain, dma_addr_t base, > goto done_unlock; > } > > + if (!iovad->rcaches) { > + pr_warn("IOVA domain rcache not properly initialised\n"); > + ret = -EFAULT; > + goto done_unlock; > + } > + > ret = 0; > goto done_unlock; > If the iovad->rcaches allocation failed, will skip iommu domain dma ops, so no need *any* iovad,->rcaches check, right ?
and there is already warning about the fallback.
Thanks,
Ethan
> > But I figure that you don't want more crud there now, considering the > work you mention above. > > Thanks, > John > > > -- "firm, enduring, strong, and long-lived"
| |