// 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/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 = dev_fwnode(&pdev->dev);
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 = dev_fwnode(&pdev->dev);
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_early_init - Test the presence of VIOT and enable ACS
*
* If the VIOT does exist, ACS must be enabled. This cannot be
* done in acpi_viot_init() which is called after the bus scan
*/
void __init acpi_viot_early_init(void)
{
#ifdef CONFIG_PCI
acpi_status status;
struct acpi_table_header *hdr;
status = acpi_get_table(ACPI_SIG_VIOT, 0, &hdr);
if (ACPI_FAILURE(status))
return;
pci_request_acs();
acpi_put_table(hdr);
#endif
}
/**
* 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)
{
if (!viommu || !IS_ENABLED(CONFIG_VIRTIO_IOMMU))
return -ENODEV;
/* We're not translating ourself */
if (device_match_fwnode(dev, viommu->fwnode))
return -EINVAL;
return acpi_iommu_fwspec_init(dev, epid, viommu->fwnode);
}
static int viot_pci_dev_iommu_init(struct pci_dev *pdev, u16 dev_id, void *data)
{
u32 epid;
struct viot_endpoint *ep;
struct device *aliased_dev = data;
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;
return viot_dev_iommu_init(aliased_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, dev);
else if (dev_is_platform(dev))
return viot_mmio_dev_iommu_init(to_platform_device(dev));
return -ENODEV;
}
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