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Date: Wed, 4 Aug 2021 00:10:45 +0530
From: Praveen Kumar <kumarpraveen@...ux.microsoft.com>
To: Wei Liu <wei.liu@...nel.org>,
Linux on Hyper-V List <linux-hyperv@...r.kernel.org>
Cc: virtualization@...ts.linux-foundation.org,
Linux Kernel List <linux-kernel@...r.kernel.org>,
Michael Kelley <mikelley@...rosoft.com>,
Vineeth Pillai <viremana@...ux.microsoft.com>,
Sunil Muthuswamy <sunilmut@...rosoft.com>,
Nuno Das Neves <nunodasneves@...ux.microsoft.com>,
pasha.tatashin@...een.com, Joerg Roedel <joro@...tes.org>,
Will Deacon <will@...nel.org>,
"K. Y. Srinivasan" <kys@...rosoft.com>,
Haiyang Zhang <haiyangz@...rosoft.com>,
Stephen Hemminger <sthemmin@...rosoft.com>,
Dexuan Cui <decui@...rosoft.com>,
"open list:IOMMU DRIVERS" <iommu@...ts.linux-foundation.org>
Subject: Re: [RFC v1 5/8] mshv: add paravirtualized IOMMU support
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 ?
Do we have any specific error code EBUSY (kind of) which we need to wait upon ?
> +
> + 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 ?
> + else
> + vdev->domain = domain;
> +
> + return hv_status_to_errno(status);
> +}
> +
> +static void hv_iommu_detach_dev(struct iommu_domain *d, struct device *dev)
> +{
> + u64 status;
> + unsigned long flags;
> + struct hv_input_detach_device_domain *input;
> + struct pci_dev *pdev;
> + struct hv_iommu_domain *domain = to_hv_iommu_domain(d);
> + struct hv_iommu_endpoint *vdev = dev_iommu_priv_get(dev);
> +
> + /* See the attach function, only PCI devices for now */
> + if (!dev_is_pci(dev))
> + return;
> +
> + pdev = to_pci_dev(dev);
> +
> + dev_dbg(dev, "Detaching from %d\n", domain->device_domain.domain_id.id);
> +
> + local_irq_save(flags);
> + input = *this_cpu_ptr(hyperv_pcpu_input_arg);
> + memset(input, 0, sizeof(*input));
> +
> + input->partition_id = HV_PARTITION_ID_SELF;
> + input->device_id = hv_build_pci_dev_id(pdev);
> +
> + status = hv_do_hypercall(HVCALL_DETACH_DEVICE_DOMAIN, input, NULL);
> + local_irq_restore(flags);
> +
> + if (!hv_result_success(status))
> + pr_err("%s: hypercall failed, status %lld\n", __func__, status);
> +
> + vdev->domain = NULL;
> +}
> +
> +static int hv_iommu_add_mapping(struct hv_iommu_domain *domain, unsigned long iova,
> + phys_addr_t paddr, size_t size, u32 flags)
> +{
> + unsigned long irqflags;
> + struct hv_iommu_mapping *mapping;
> +
> + mapping = kzalloc(sizeof(*mapping), GFP_ATOMIC);
> + if (!mapping)
> + return -ENOMEM;
> +
> + mapping->paddr = paddr;
> + mapping->iova.start = iova;
> + mapping->iova.last = iova + size - 1;
> + mapping->flags = flags;
> +
> + spin_lock_irqsave(&domain->mappings_lock, irqflags);
> + interval_tree_insert(&mapping->iova, &domain->mappings);
> + spin_unlock_irqrestore(&domain->mappings_lock, irqflags);
> +
> + return 0;
> +}
> +
> +static size_t hv_iommu_del_mappings(struct hv_iommu_domain *domain,
> + unsigned long iova, size_t size)
> +{
> + unsigned long flags;
> + size_t unmapped = 0;
> + unsigned long last = iova + size - 1;
> + struct hv_iommu_mapping *mapping = NULL;
> + struct interval_tree_node *node, *next;
> +
> + spin_lock_irqsave(&domain->mappings_lock, flags);
> + next = interval_tree_iter_first(&domain->mappings, iova, last);
> + while (next) {
> + node = next;
> + mapping = container_of(node, struct hv_iommu_mapping, iova);
> + next = interval_tree_iter_next(node, iova, last);
> +
> + /* Trying to split a mapping? Not supported for now. */
> + if (mapping->iova.start < iova)
> + break;
> +
> + unmapped += mapping->iova.last - mapping->iova.start + 1;
> +
> + interval_tree_remove(node, &domain->mappings);
> + kfree(mapping);
> + }
> + spin_unlock_irqrestore(&domain->mappings_lock, flags);
> +
> + return unmapped;
> +}
> +
> +static int hv_iommu_map(struct iommu_domain *d, unsigned long iova,
> + phys_addr_t paddr, size_t size, int prot, gfp_t gfp)
> +{
> + u32 map_flags;
> + unsigned long flags, pfn, npages;
> + int ret, i;
> + struct hv_iommu_domain *domain = to_hv_iommu_domain(d);
> + struct hv_input_map_device_gpa_pages *input;
> + u64 status;
> +
> + /* Reject size that's not a whole page */
> + if (size & ~HV_HYP_PAGE_MASK)
> + return -EINVAL;
> +
> + map_flags = HV_MAP_GPA_READABLE; /* Always required */
> + map_flags |= prot & IOMMU_WRITE ? HV_MAP_GPA_WRITABLE : 0;
> +
> + ret = hv_iommu_add_mapping(domain, iova, paddr, size, flags);
> + if (ret)
> + return ret;
> +
> + npages = size >> HV_HYP_PAGE_SHIFT;
> +
> + local_irq_save(flags);
> + input = *this_cpu_ptr(hyperv_pcpu_input_arg);
> + memset(input, 0, sizeof(*input));
> +
> + input->device_domain = domain->device_domain;
> + input->map_flags = map_flags;
> + input->target_device_va_base = iova;
> +
> + pfn = paddr >> HV_HYP_PAGE_SHIFT;
> + for (i = 0; i < npages; i++) {
> + input->gpa_page_list[i] = pfn;
> + pfn += 1;
> + }
> +
> + status = hv_do_rep_hypercall(HVCALL_MAP_DEVICE_GPA_PAGES, npages, 0,
> + input, NULL);
> +
> + local_irq_restore(flags);
> +
> + if (!hv_result_success(status)) {
> + pr_err("%s: hypercall failed, status %lld\n", __func__, status);
> + hv_iommu_del_mappings(domain, iova, size);
> + }
> +
> + 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 ?
> +
> + npages = size >> HV_HYP_PAGE_SHIFT;
> +
> + local_irq_save(flags);
> + input = *this_cpu_ptr(hyperv_pcpu_input_arg);
> + memset(input, 0, sizeof(*input));
> +
> + input->device_domain = domain->device_domain;
> + input->target_device_va_base = iova;
> +
> + /* Unmap `npages` pages starting from VA base */
> + status = hv_do_rep_hypercall(HVCALL_UNMAP_DEVICE_GPA_PAGES, npages,
> + 0, input, NULL);
> +
> + local_irq_restore(flags);
> +
> + if (!hv_result_success(status))
> + pr_err("%s: hypercall failed, status %lld\n", __func__, status);
> +
> + return hv_result_success(status) ? unmapped : 0;
> +}
> +
Regards,
~Praveen.
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