Messages in this thread | | | Date | Thu, 14 May 2020 08:57:45 -0700 | From | Jacob Pan <> | Subject | Re: [PATCH v13 4/8] iommu/vt-d: Add bind guest PASID support |
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Hi Christoph,
Thanks a lot for the reviews, comments below.
Jacob
On Wed, 13 May 2020 22:59:30 -0700 Christoph Hellwig <hch@infradead.org> wrote:
> > + if (dev_is_pci(dev)) { > > + /* VT-d supports devices with full 20 bit PASIDs > > only */ > > + if (pci_max_pasids(to_pci_dev(dev)) != PASID_MAX) > > + return -EINVAL; > > + } else { > > + return -ENOTSUPP; > > + } > > This looks strange. Why not: > > if (!dev_is_pci(dev)) { > return -ENOTSUPP; > > /* VT-d supports devices with full 20 bit PASIDs only */ > if (pci_max_pasids(to_pci_dev(dev)) != PASID_MAX) > return -EINVAL; > That is better, will do.
> > + for_each_svm_dev(sdev, svm, dev) { > > + /* > > + * For devices with aux domains, we should > > allow multiple > > + * bind calls with the same PASID and pdev. > > + */ > > + if (iommu_dev_feature_enabled(dev, > > IOMMU_DEV_FEAT_AUX)) { > > + sdev->users++; > > + } else { > > + dev_warn_ratelimited(dev, "Already > > bound with PASID %u\n", > > + svm->pasid); > > + ret = -EBUSY; > > + } > > + goto out; > > Is this intentionally a for loop that jumps out of the loop after > the first device? > The name is confusing, it is not a loop. I will change it to find_svm_dev() and comments like this?
/* * Find the matching device in a given SVM. The bind code ensures that * each device can only be added to the SVM list once. */ #define find_svm_dev(sdev, svm, d) \ list_for_each_entry((sdev), &(svm)->devs, list) \ if ((d) != (sdev)->dev) {} else
> > + /* > > + * PASID table is per device for better security. > > Therefore, for > > + * each bind of a new device even with an existing PASID, > > we need to > > + * call the nested mode setup function here. > > + */ > > + spin_lock(&iommu->lock); > > + ret = intel_pasid_setup_nested(iommu, > > + dev, > > + (pgd_t *)data->gpgd, > > + data->hpasid, > > + &data->vtd, > > + dmar_domain, > > + data->addr_width); > > Why not: > > et = intel_pasid_setup_nested(iommu, dev, (pgd_t *)data->gpgd, > data->hpasid, &data->vtd, dmar_domain, > data->addr_width); > > ? > I thought we want to align the parentheses? Either way is fine. Baolu?
> > + for_each_svm_dev(sdev, svm, dev) { > > + ret = 0; > > ... > > > + break; > > + } > > Same only looks at the first device style. Why dos it only care about > the first device? That needs at least a comment, and probably a > first_svm_dev or so heper to make it explicit.
Yes, same as above. change to find_svm_dev() since there should be at most one matching device in the svm list.
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