On Wed, Aug 04, 2021 at 12:10:45AM +0530, Praveen Kumar wrote:
> On 09-07-2021 17:13, Wei Liu wrote:
> > +static void hv_iommu_domain_free(struct iommu_domain *d)
> > +{
> > + struct hv_iommu_domain *domain = to_hv_iommu_domain(d);
> > + unsigned long flags;
> > + u64 status;
> > + struct hv_input_delete_device_domain *input;
> > +
> > + if (is_identity_domain(domain) || is_null_domain(domain))
> > + return;
> > +
> > + local_irq_save(flags);
> > + input = *this_cpu_ptr(hyperv_pcpu_input_arg);
> > + memset(input, 0, sizeof(*input));
> > +
> > + input->device_domain= domain->device_domain;
> > +
> > + status = hv_do_hypercall(HVCALL_DELETE_DEVICE_DOMAIN, input, NULL);
> > +
> > + local_irq_restore(flags);
> > +
> > + if (!hv_result_success(status))
> > + pr_err("%s: hypercall failed, status %lld\n", __func__, status);
>
> Is it OK to deallocate the resources, if hypercall has failed ?
It should be fine. We leak some resources in the hypervisor, but Linux
is in a rather wedged state anyway. Refusing to free up resources in
Linux does not much good.
> Do we have any specific error code EBUSY (kind of) which we need to wait upon ?
>
I have not found a circumstance that can happen.
> > +
> > + ida_free(&domain->hv_iommu->domain_ids, domain->device_domain.domain_id.id);
> > +
> > + iommu_put_dma_cookie(d);
> > +
> > + kfree(domain);
> > +}
> > +
> > +static int hv_iommu_attach_dev(struct iommu_domain *d, struct device *dev)
> > +{
> > + struct hv_iommu_domain *domain = to_hv_iommu_domain(d);
> > + u64 status;
> > + unsigned long flags;
> > + struct hv_input_attach_device_domain *input;
> > + struct pci_dev *pdev;
> > + struct hv_iommu_endpoint *vdev = dev_iommu_priv_get(dev);
> > +
> > + /* Only allow PCI devices for now */
> > + if (!dev_is_pci(dev))
> > + return -EINVAL;
> > +
> > + pdev = to_pci_dev(dev);
> > +
> > + dev_dbg(dev, "Attaching (%strusted) to %d\n", pdev->untrusted ? "un" : "",
> > + domain->device_domain.domain_id.id);
> > +
> > + local_irq_save(flags);
> > + input = *this_cpu_ptr(hyperv_pcpu_input_arg);
> > + memset(input, 0, sizeof(*input));
> > +
> > + input->device_domain = domain->device_domain;
> > + input->device_id = hv_build_pci_dev_id(pdev);
> > +
> > + status = hv_do_hypercall(HVCALL_ATTACH_DEVICE_DOMAIN, input, NULL);
> > + local_irq_restore(flags);
> > +
> > + if (!hv_result_success(status))
> > + pr_err("%s: hypercall failed, status %lld\n", __func__, status);
>
> Does it make sense to vdev->domain = NULL ?
>
It is already NULL -- there is no other code path that sets it and the
detach path always sets the field to NULL.
> > + else
> > + vdev->domain = domain;
> > +
> > + return hv_status_to_errno(status);
> > +}
> > +
[...]
> > +static size_t hv_iommu_unmap(struct iommu_domain *d, unsigned long iova,
> > + size_t size, struct iommu_iotlb_gather *gather)
> > +{
> > + size_t unmapped;
> > + struct hv_iommu_domain *domain = to_hv_iommu_domain(d);
> > + unsigned long flags, npages;
> > + struct hv_input_unmap_device_gpa_pages *input;
> > + u64 status;
> > +
> > + unmapped = hv_iommu_del_mappings(domain, iova, size);
> > + if (unmapped < size)
> > + return 0;
>
> Is there a case where unmapped > 0 && unmapped < size ?
>
There could be such a case -- hv_iommu_del_mappings' return value is >= 0.
Is there a problem with this predicate?
Wei.
