Messages in this thread | | | Date | Sat, 3 Aug 2019 23:34:54 +0200 | From | Pavel Machek <> | Subject | Re: [PATCH 4.19 17/32] iommu/vt-d: Dont queue_iova() if there is no flush queue |
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Hi!
> --- a/drivers/iommu/intel-iommu.c > +++ b/drivers/iommu/intel-iommu.c > @@ -3721,7 +3721,7 @@ static void intel_unmap(struct device *d > > freelist = domain_unmap(domain, start_pfn, last_pfn); > > - if (intel_iommu_strict) { > + if (intel_iommu_strict || !has_iova_flush_queue(&domain->iovad)) { > iommu_flush_iotlb_psi(iommu, domain, start_pfn, > nrpages, !freelist, 0); > /* free iova */ > --- a/drivers/iommu/iova.c > +++ b/drivers/iommu/iova.c > @@ -65,9 +65,14 @@ init_iova_domain(struct iova_domain *iov > } > EXPORT_SYMBOL_GPL(init_iova_domain); > > +bool has_iova_flush_queue(struct iova_domain *iovad) > +{ > + return !!iovad->fq;
Should this be READ_ONCE()?
> @@ -100,13 +106,17 @@ int init_iova_flush_queue(struct iova_do > for_each_possible_cpu(cpu) { > struct iova_fq *fq; > > - fq = per_cpu_ptr(iovad->fq, cpu); > + fq = per_cpu_ptr(queue, cpu); > fq->head = 0; > fq->tail = 0; > > spin_lock_init(&fq->lock); > } > > + smp_wmb(); > + > + iovad->fq = queue; > +
Could we have a comment why the barrier is needed, and perhaps there should be oposing smp_rmb() somewhere? Does this need to be WRITE_ONCE() as it is racing against reader?
Thanks, Pavel
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