--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Virtual I/O topology
+ *
+ * The Virtual I/O Translation Table (VIOT) describes the topology of
+ * para-virtual IOMMUs and the endpoints they manage. The OS uses it to
+ * initialize devices in the right order, preventing endpoints from issuing DMA
+ * before their IOMMU is ready.
+ *
+ * When binding a driver to a device, before calling the device driver's probe()
+ * method, the driver infrastructure calls dma_configure(). At that point the
+ * VIOT driver looks for an IOMMU associated to the device in the VIOT table.
+ * If an IOMMU exists and has been initialized, the VIOT driver initializes the
+ * device's IOMMU fwspec, allowing the DMA infrastructure to invoke the IOMMU
+ * ops when the device driver configures DMA mappings. If an IOMMU exists and
+ * hasn't yet been initialized, VIOT returns -EPROBE_DEFER to postpone probing
+ * the device until the IOMMU is available.
+ */
+#define pr_fmt(fmt) "ACPI: VIOT: " fmt
+
+#include <linux/acpi_viot.h>
+#include <linux/dma-iommu.h>
+#include <linux/fwnode.h>
+#include <linux/iommu.h>
+#include <linux/list.h>
+#include <linux/pci.h>
+#include <linux/platform_device.h>
+
+struct viot_iommu {
+ /* Node offset within the table */
+ unsigned int offset;
+ struct fwnode_handle *fwnode;
+ struct list_head list;
+};
+
+struct viot_endpoint {
+ union {
+ /* PCI range */
+ struct {
+ u16 segment_start;
+ u16 segment_end;
+ u16 bdf_start;
+ u16 bdf_end;
+ };
+ /* MMIO */
+ u64 address;
+ };
+ u32 endpoint_id;
+ struct viot_iommu *viommu;
+ struct list_head list;
+};
+
+static struct acpi_table_viot *viot;
+static LIST_HEAD(viot_iommus);
+static LIST_HEAD(viot_pci_ranges);
+static LIST_HEAD(viot_mmio_endpoints);
+
+static int __init viot_check_bounds(const struct acpi_viot_header *hdr)
+{
+ struct acpi_viot_header *start, *end, *hdr_end;
+
+ start = ACPI_ADD_PTR(struct acpi_viot_header, viot,
+ max_t(size_t, sizeof(*viot), viot->node_offset));
+ end = ACPI_ADD_PTR(struct acpi_viot_header, viot, viot->header.length);
+ hdr_end = ACPI_ADD_PTR(struct acpi_viot_header, hdr, sizeof(*hdr));
+
+ if (hdr < start || hdr_end > end) {
+ pr_err(FW_BUG "Node pointer overflows\n");
+ return -EOVERFLOW;
+ }
+ if (hdr->length < sizeof(*hdr)) {
+ pr_err(FW_BUG "Empty node\n");
+ return -EINVAL;
+ }
+ return 0;
+}
+
+static int __init viot_get_pci_iommu_fwnode(struct viot_iommu *viommu,
+ u16 segment, u16 bdf)
+{
+ struct pci_dev *pdev;
+ struct fwnode_handle *fwnode;
+
+ pdev = pci_get_domain_bus_and_slot(segment, PCI_BUS_NUM(bdf),
+ bdf & 0xff);
+ if (!pdev) {
+ pr_err("Could not find PCI IOMMU\n");
+ return -ENODEV;
+ }
+
+ fwnode = pdev->dev.fwnode;
+ if (!fwnode) {
+ /*
+ * PCI devices aren't necessarily described by ACPI. Create a
+ * fwnode so the IOMMU subsystem can identify this device.
+ */
+ fwnode = acpi_alloc_fwnode_static();
+ if (!fwnode) {
+ pci_dev_put(pdev);
+ return -ENOMEM;
+ }
+ set_primary_fwnode(&pdev->dev, fwnode);
+ }
+ viommu->fwnode = pdev->dev.fwnode;
+ pci_dev_put(pdev);
+ return 0;
+}
+
+static int __init viot_get_mmio_iommu_fwnode(struct viot_iommu *viommu,
+ u64 address)
+{
+ struct acpi_device *adev;
+ struct resource res = {
+ .start = address,
+ .end = address,
+ .flags = IORESOURCE_MEM,
+ };
+
+ adev = acpi_resource_consumer(&res);
+ if (!adev) {
+ pr_err("Could not find MMIO IOMMU\n");
+ return -EINVAL;
+ }
+ viommu->fwnode = &adev->fwnode;
+ return 0;
+}
+
+static struct viot_iommu * __init viot_get_iommu(unsigned int offset)
+{
+ int ret;
+ struct viot_iommu *viommu;
+ struct acpi_viot_header *hdr = ACPI_ADD_PTR(struct acpi_viot_header,
+ viot, offset);
+ union {
+ struct acpi_viot_virtio_iommu_pci pci;
+ struct acpi_viot_virtio_iommu_mmio mmio;
+ } *node = (void *)hdr;
+
+ list_for_each_entry(viommu, &viot_iommus, list)
+ if (viommu->offset == offset)
+ return viommu;
+
+ if (viot_check_bounds(hdr))
+ return NULL;
+
+ viommu = kzalloc(sizeof(*viommu), GFP_KERNEL);
+ if (!viommu)
+ return NULL;
+
+ viommu->offset = offset;
+ switch (hdr->type) {
+ case ACPI_VIOT_NODE_VIRTIO_IOMMU_PCI:
+ if (hdr->length < sizeof(node->pci))
+ goto err_free;
+
+ ret = viot_get_pci_iommu_fwnode(viommu, node->pci.segment,
+ node->pci.bdf);
+ break;
+ case ACPI_VIOT_NODE_VIRTIO_IOMMU_MMIO:
+ if (hdr->length < sizeof(node->mmio))
+ goto err_free;
+
+ ret = viot_get_mmio_iommu_fwnode(viommu,
+ node->mmio.base_address);
+ break;
+ default:
+ ret = -EINVAL;
+ }
+ if (ret)
+ goto err_free;
+
+ list_add(&viommu->list, &viot_iommus);
+ return viommu;
+
+err_free:
+ kfree(viommu);
+ return NULL;
+}
+
+static int __init viot_parse_node(const struct acpi_viot_header *hdr)
+{
+ int ret = -EINVAL;
+ struct list_head *list;
+ struct viot_endpoint *ep;
+ union {
+ struct acpi_viot_mmio mmio;
+ struct acpi_viot_pci_range pci;
+ } *node = (void *)hdr;
+
+ if (viot_check_bounds(hdr))
+ return -EINVAL;
+
+ if (hdr->type == ACPI_VIOT_NODE_VIRTIO_IOMMU_PCI ||
+ hdr->type == ACPI_VIOT_NODE_VIRTIO_IOMMU_MMIO)
+ return 0;
+
+ ep = kzalloc(sizeof(*ep), GFP_KERNEL);
+ if (!ep)
+ return -ENOMEM;
+
+ switch (hdr->type) {
+ case ACPI_VIOT_NODE_PCI_RANGE:
+ if (hdr->length < sizeof(node->pci)) {
+ pr_err(FW_BUG "Invalid PCI node size\n");
+ goto err_free;
+ }
+
+ ep->segment_start = node->pci.segment_start;
+ ep->segment_end = node->pci.segment_end;
+ ep->bdf_start = node->pci.bdf_start;
+ ep->bdf_end = node->pci.bdf_end;
+ ep->endpoint_id = node->pci.endpoint_start;
+ ep->viommu = viot_get_iommu(node->pci.output_node);
+ list = &viot_pci_ranges;
+ break;
+ case ACPI_VIOT_NODE_MMIO:
+ if (hdr->length < sizeof(node->mmio)) {
+ pr_err(FW_BUG "Invalid MMIO node size\n");
+ goto err_free;
+ }
+
+ ep->address = node->mmio.base_address;
+ ep->endpoint_id = node->mmio.endpoint;
+ ep->viommu = viot_get_iommu(node->mmio.output_node);
+ list = &viot_mmio_endpoints;
+ break;
+ default:
+ pr_warn("Unsupported node %x\n", hdr->type);
+ ret = 0;
+ goto err_free;
+ }
+
+ if (!ep->viommu) {
+ pr_warn("No IOMMU node found\n");
+ /*
+ * A future version of the table may use the node for other
+ * purposes. Keep parsing.
+ */
+ ret = 0;
+ goto err_free;
+ }
+
+ list_add(&ep->list, list);
+ return 0;
+
+err_free:
+ kfree(ep);
+ return ret;
+}
+
+/**
+ * acpi_viot_init - Parse the VIOT table
+ *
+ * Parse the VIOT table, prepare the list of endpoints to be used during DMA
+ * setup of devices.
+ */
+void __init acpi_viot_init(void)
+{
+ int i;
+ acpi_status status;
+ struct acpi_table_header *hdr;
+ struct acpi_viot_header *node;
+
+ status = acpi_get_table(ACPI_SIG_VIOT, 0, &hdr);
+ if (ACPI_FAILURE(status)) {
+ if (status != AE_NOT_FOUND) {
+ const char *msg = acpi_format_exception(status);
+
+ pr_err("Failed to get table, %s\n", msg);
+ }
+ return;
+ }
+
+ viot = (void *)hdr;
+
+ node = ACPI_ADD_PTR(struct acpi_viot_header, viot, viot->node_offset);
+ for (i = 0; i < viot->node_count; i++) {
+ if (viot_parse_node(node))
+ return;
+
+ node = ACPI_ADD_PTR(struct acpi_viot_header, node,
+ node->length);
+ }
+
+ acpi_put_table(hdr);
+}
+
+static int viot_dev_iommu_init(struct device *dev, struct viot_iommu *viommu,
+ u32 epid)
+{
+ const struct iommu_ops *ops;
+
+ if (!viommu)
+ return -ENODEV;
+
+ /* We're not translating ourself */
+ if (viommu->fwnode == dev->fwnode)
+ return -EINVAL;
+
+ ops = iommu_ops_from_fwnode(viommu->fwnode);
+ if (!ops)
+ return IS_ENABLED(CONFIG_VIRTIO_IOMMU) ?
+ -EPROBE_DEFER : -ENODEV;
+
+ return acpi_iommu_fwspec_init(dev, epid, viommu->fwnode, ops);
+}
+
+static int viot_pci_dev_iommu_init(struct pci_dev *pdev, u16 dev_id, void *data)
+{
+ u32 epid;
+ struct viot_endpoint *ep;
+ u32 domain_nr = pci_domain_nr(pdev->bus);
+
+ list_for_each_entry(ep, &viot_pci_ranges, list) {
+ if (domain_nr >= ep->segment_start &&
+ domain_nr <= ep->segment_end &&
+ dev_id >= ep->bdf_start &&
+ dev_id <= ep->bdf_end) {
+ epid = ((domain_nr - ep->segment_start) << 16) +
+ dev_id - ep->bdf_start + ep->endpoint_id;
+
+ /*
+ * If we found a PCI range managed by the viommu, we're
+ * the one that has to request ACS.
+ */
+ pci_request_acs();
+
+ return viot_dev_iommu_init(&pdev->dev, ep->viommu,
+ epid);
+ }
+ }
+ return -ENODEV;
+}
+
+static int viot_mmio_dev_iommu_init(struct platform_device *pdev)
+{
+ struct resource *mem;
+ struct viot_endpoint *ep;
+
+ mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!mem)
+ return -ENODEV;
+
+ list_for_each_entry(ep, &viot_mmio_endpoints, list) {
+ if (ep->address == mem->start)
+ return viot_dev_iommu_init(&pdev->dev, ep->viommu,
+ ep->endpoint_id);
+ }
+ return -ENODEV;
+}
+
+/**
+ * viot_iommu_configure - Setup IOMMU ops for an endpoint described by VIOT
+ * @dev: the endpoint
+ *
+ * Return: 0 on success, <0 on failure
+ */
+int viot_iommu_configure(struct device *dev)
+{
+ if (dev_is_pci(dev))
+ return pci_for_each_dma_alias(to_pci_dev(dev),
+ viot_pci_dev_iommu_init, NULL);
+ else if (dev_is_platform(dev))
+ return viot_mmio_dev_iommu_init(to_platform_device(dev));
+ return -ENODEV;
+}
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