On Thu, Jun 10, 2021 at 10:03 AM Jean-Philippe Brucker
<jean-philippe@xxxxxxxxxx> wrote:
>
> The ACPI Virtual I/O Translation Table describes topology of
> para-virtual platforms, similarly to vendor tables DMAR, IVRS and IORT.
> For now it describes the relation between virtio-iommu and the endpoints
> it manages.
>
> Three steps are needed to configure DMA of endpoints:
>
> (1) acpi_viot_init(): parse the VIOT table, find or create the fwnode
> associated to each vIOMMU device.
>
> (2) When probing the vIOMMU device, the driver registers its IOMMU ops
> within the IOMMU subsystem. This step doesn't require any
> intervention from the VIOT driver.
>
> (3) viot_iommu_configure(): before binding the endpoint to a driver,
> find the associated IOMMU ops. Register them, along with the
> endpoint ID, into the device's iommu_fwspec.
>
> If step (3) happens before step (2), it is deferred until the IOMMU is
> initialized, then retried.
>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>
> ---
> drivers/acpi/Kconfig | 3 +
> drivers/iommu/Kconfig | 1 +
> drivers/acpi/Makefile | 2 +
> include/linux/acpi_viot.h | 19 ++
> drivers/acpi/bus.c | 2 +
> drivers/acpi/scan.c | 3 +
> drivers/acpi/viot.c | 364 ++++++++++++++++++++++++++++++++++++++
> MAINTAINERS | 8 +
> 8 files changed, 402 insertions(+)
> create mode 100644 include/linux/acpi_viot.h
> create mode 100644 drivers/acpi/viot.c
>
> diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
> index eedec61e3476..3758c6940ed7 100644
> --- a/drivers/acpi/Kconfig
> +++ b/drivers/acpi/Kconfig
> @@ -526,6 +526,9 @@ endif
>
> source "drivers/acpi/pmic/Kconfig"
>
> +config ACPI_VIOT
> + bool
> +
> endif # ACPI
>
> config X86_PM_TIMER
> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> index 1f111b399bca..aff8a4830dd1 100644
> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -403,6 +403,7 @@ config VIRTIO_IOMMU
> depends on ARM64
> select IOMMU_API
> select INTERVAL_TREE
> + select ACPI_VIOT if ACPI
> help
> Para-virtualised IOMMU driver with virtio.
>
> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> index 700b41adf2db..a6e644c48987 100644
> --- a/drivers/acpi/Makefile
> +++ b/drivers/acpi/Makefile
> @@ -118,3 +118,5 @@ video-objs += acpi_video.o video_detect.o
> obj-y += dptf/
>
> obj-$(CONFIG_ARM64) += arm64/
> +
> +obj-$(CONFIG_ACPI_VIOT) += viot.o
> diff --git a/include/linux/acpi_viot.h b/include/linux/acpi_viot.h
> new file mode 100644
> index 000000000000..1eb8ee5b0e5f
> --- /dev/null
> +++ b/include/linux/acpi_viot.h
> @@ -0,0 +1,19 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +
> +#ifndef __ACPI_VIOT_H__
> +#define __ACPI_VIOT_H__
> +
> +#include <linux/acpi.h>
> +
> +#ifdef CONFIG_ACPI_VIOT
> +void __init acpi_viot_init(void);
> +int viot_iommu_configure(struct device *dev);
> +#else
> +static inline void acpi_viot_init(void) {}
> +static inline int viot_iommu_configure(struct device *dev)
> +{
> + return -ENODEV;
> +}
> +#endif
> +
> +#endif /* __ACPI_VIOT_H__ */
> diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
> index be7da23fad76..b835ca702ff0 100644
> --- a/drivers/acpi/bus.c
> +++ b/drivers/acpi/bus.c
> @@ -27,6 +27,7 @@
> #include <linux/dmi.h>
> #endif
> #include <linux/acpi_iort.h>
> +#include <linux/acpi_viot.h>
> #include <linux/pci.h>
> #include <acpi/apei.h>
> #include <linux/suspend.h>
> @@ -1339,6 +1340,7 @@ static int __init acpi_init(void)
> pci_mmcfg_late_init();
> acpi_iort_init();
> acpi_scan_init();
> + acpi_viot_init();
Is there a specific reason why to call it right here?
In particular, does it need to be called after acpi_scan_init()? And
does it need to be called before the subsequent functions? If so,
then why?
> acpi_ec_init();
> acpi_debugfs_init();
> acpi_sleep_proc_init();
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 0c53c8533300..4fa684fdfda8 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -9,6 +9,7 @@
> #include <linux/kernel.h>
> #include <linux/acpi.h>
> #include <linux/acpi_iort.h>
> +#include <linux/acpi_viot.h>
> #include <linux/iommu.h>
> #include <linux/signal.h>
> #include <linux/kthread.h>
> @@ -1556,6 +1557,8 @@ static const struct iommu_ops *acpi_iommu_configure_id(struct device *dev,
> return ops;
>
> err = iort_iommu_configure_id(dev, id_in);
> + if (err && err != -EPROBE_DEFER)
> + err = viot_iommu_configure(dev);
>
> /*
> * If we have reason to believe the IOMMU driver missed the initial
> diff --git a/drivers/acpi/viot.c b/drivers/acpi/viot.c
> new file mode 100644
> index 000000000000..892cd9fa7b6d
> --- /dev/null
> +++ b/drivers/acpi/viot.c
> @@ -0,0 +1,364 @@
> +// 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;
> + }
> +
> + /*
> + * To be compatible with future versions of the table which may include
> + * other node types, keep parsing.
> + */
> + if (!ep->viommu) {
> + pr_warn("No IOMMU node found\n");
> + 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);
> + }
Do you still need the table after the above is complete? If not,
release the reference on it acquired above.
> +}
> +
> +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;
> +}
> diff --git a/MAINTAINERS b/MAINTAINERS
> index b706dd20ff2b..8d71591f979a 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -431,6 +431,14 @@ W: https://01.org/linux-acpi
> B: https://bugzilla.kernel.org
> F: drivers/acpi/acpi_video.c
>
> +ACPI VIOT DRIVER
> +M: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>
> +L: linux-acpi@xxxxxxxxxxxxxxx
> +L: iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx
> +S: Maintained
> +F: drivers/acpi/viot.c
> +F: include/linux/acpi_viot.h
> +
> ACPI WMI DRIVER
> L: platform-driver-x86@xxxxxxxxxxxxxxx
> S: Orphan
> --
> 2.31.1
>
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