On Fri, Oct 12, 2018 at 03:59:15PM +0100, Jean-Philippe Brucker wrote:
> The virtio IOMMU is a para-virtualized device, allowing to send IOMMU
> requests such as map/unmap over virtio transport without emulating page
> tables. This implementation handles ATTACH, DETACH, MAP and UNMAP
> requests.
>
> The bulk of the code transforms calls coming from the IOMMU API into
> corresponding virtio requests. Mappings are kept in an interval tree
> instead of page tables.
>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@xxxxxxx>
> ---
> MAINTAINERS | 7 +
> drivers/iommu/Kconfig | 11 +
> drivers/iommu/Makefile | 1 +
> drivers/iommu/virtio-iommu.c | 938 ++++++++++++++++++++++++++++++
> include/uapi/linux/virtio_ids.h | 1 +
> include/uapi/linux/virtio_iommu.h | 101 ++++
> 6 files changed, 1059 insertions(+)
> create mode 100644 drivers/iommu/virtio-iommu.c
> create mode 100644 include/uapi/linux/virtio_iommu.h
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 48a65c3a4189..f02fa65f47e2 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -15599,6 +15599,13 @@ S: Maintained
> F: drivers/virtio/virtio_input.c
> F: include/uapi/linux/virtio_input.h
>
> +VIRTIO IOMMU DRIVER
> +M: Jean-Philippe Brucker <jean-philippe.brucker@xxxxxxx>
> +L: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
> +S: Maintained
> +F: drivers/iommu/virtio-iommu.c
> +F: include/uapi/linux/virtio_iommu.h
> +
> VIRTUAL BOX GUEST DEVICE DRIVER
> M: Hans de Goede <hdegoede@xxxxxxxxxx>
> M: Arnd Bergmann <arnd@xxxxxxxx>
> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> index c60395b7470f..2dc016dc2b92 100644
> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -414,4 +414,15 @@ config QCOM_IOMMU
> help
> Support for IOMMU on certain Qualcomm SoCs.
>
> +config VIRTIO_IOMMU
> + bool "Virtio IOMMU driver"
> + depends on VIRTIO=y
> + select IOMMU_API
> + select INTERVAL_TREE
> + select ARM_DMA_USE_IOMMU if ARM
> + help
> + Para-virtualised IOMMU driver with virtio.
> +
> + Say Y here if you intend to run this kernel as a guest.
> +
> endif # IOMMU_SUPPORT
> diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
> index ab5eba6edf82..4cd643408e49 100644
> --- a/drivers/iommu/Makefile
> +++ b/drivers/iommu/Makefile
> @@ -31,3 +31,4 @@ obj-$(CONFIG_EXYNOS_IOMMU) += exynos-iommu.o
> obj-$(CONFIG_FSL_PAMU) += fsl_pamu.o fsl_pamu_domain.o
> obj-$(CONFIG_S390_IOMMU) += s390-iommu.o
> obj-$(CONFIG_QCOM_IOMMU) += qcom_iommu.o
> +obj-$(CONFIG_VIRTIO_IOMMU) += virtio-iommu.o
> diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c
> new file mode 100644
> index 000000000000..9fb38cd3b727
> --- /dev/null
> +++ b/drivers/iommu/virtio-iommu.c
> @@ -0,0 +1,938 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Virtio driver for the paravirtualized IOMMU
> + *
> + * Copyright (C) 2018 Arm Limited
> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/amba/bus.h>
> +#include <linux/delay.h>
> +#include <linux/dma-iommu.h>
> +#include <linux/freezer.h>
> +#include <linux/interval_tree.h>
> +#include <linux/iommu.h>
> +#include <linux/module.h>
> +#include <linux/of_iommu.h>
> +#include <linux/of_platform.h>
> +#include <linux/pci.h>
> +#include <linux/platform_device.h>
> +#include <linux/virtio.h>
> +#include <linux/virtio_config.h>
> +#include <linux/virtio_ids.h>
> +#include <linux/wait.h>
> +
> +#include <uapi/linux/virtio_iommu.h>
> +
> +#define MSI_IOVA_BASE 0x8000000
> +#define MSI_IOVA_LENGTH 0x100000
> +
> +#define VIOMMU_REQUEST_VQ 0
> +#define VIOMMU_NR_VQS 1
> +
> +/*
> + * During development, it is convenient to time out rather than wait
> + * indefinitely in atomic context when a device misbehaves and a request doesn't
> + * return. In production however, some requests shouldn't return until they are
> + * successful.
> + */
> +#ifdef DEBUG
> +#define VIOMMU_REQUEST_TIMEOUT 10000 /* 10s */
> +#endif
> +
> +struct viommu_dev {
> + struct iommu_device iommu;
> + struct device *dev;
> + struct virtio_device *vdev;
> +
> + struct ida domain_ids;
> +
> + struct virtqueue *vqs[VIOMMU_NR_VQS];
> + spinlock_t request_lock;
> + struct list_head requests;
> +
> + /* Device configuration */
> + struct iommu_domain_geometry geometry;
> + u64 pgsize_bitmap;
> + u8 domain_bits;
> +};
> +
> +struct viommu_mapping {
> + phys_addr_t paddr;
> + struct interval_tree_node iova;
> + u32 flags;
> +};
> +
> +struct viommu_domain {
> + struct iommu_domain domain;
> + struct viommu_dev *viommu;
> + struct mutex mutex;
> + unsigned int id;
> +
> + spinlock_t mappings_lock;
> + struct rb_root_cached mappings;
> +
> + unsigned long nr_endpoints;
> +};
> +
> +struct viommu_endpoint {
> + struct viommu_dev *viommu;
> + struct viommu_domain *vdomain;
> +};
> +
> +struct viommu_request {
> + struct list_head list;
> + void *writeback;
> + unsigned int write_offset;
> + unsigned int len;
> + char buf[];
> +};
> +
> +#define to_viommu_domain(domain) \
> + container_of(domain, struct viommu_domain, domain)
> +
> +static int viommu_get_req_errno(void *buf, size_t len)
> +{
> + struct virtio_iommu_req_tail *tail = buf + len - sizeof(*tail);
> +
> + switch (tail->status) {
> + case VIRTIO_IOMMU_S_OK:
> + return 0;
> + case VIRTIO_IOMMU_S_UNSUPP:
> + return -ENOSYS;
> + case VIRTIO_IOMMU_S_INVAL:
> + return -EINVAL;
> + case VIRTIO_IOMMU_S_RANGE:
> + return -ERANGE;
> + case VIRTIO_IOMMU_S_NOENT:
> + return -ENOENT;
> + case VIRTIO_IOMMU_S_FAULT:
> + return -EFAULT;
> + case VIRTIO_IOMMU_S_IOERR:
> + case VIRTIO_IOMMU_S_DEVERR:
> + default:
> + return -EIO;
> + }
> +}
> +
> +static void viommu_set_req_status(void *buf, size_t len, int status)
> +{
> + struct virtio_iommu_req_tail *tail = buf + len - sizeof(*tail);
> +
> + tail->status = status;
> +}
> +
> +static off_t viommu_get_req_offset(struct viommu_dev *viommu,
> + struct virtio_iommu_req_head *req,
> + size_t len)
> +{
> + size_t tail_size = sizeof(struct virtio_iommu_req_tail);
> +
> + return len - tail_size;
> +}
> +
> +/*
> + * __viommu_sync_req - Complete all in-flight requests
> + *
> + * Wait for all added requests to complete. When this function returns, all
> + * requests that were in-flight at the time of the call have completed.
> + */
> +static int __viommu_sync_req(struct viommu_dev *viommu)
> +{
> + int ret = 0;
> + unsigned int len;
> + size_t write_len;
> + ktime_t timeout = 0;
> + struct viommu_request *req;
> + struct virtqueue *vq = viommu->vqs[VIOMMU_REQUEST_VQ];
> +
> + assert_spin_locked(&viommu->request_lock);
> +#ifdef DEBUG
> + timeout = ktime_add_ms(ktime_get(), VIOMMU_REQUEST_TIMEOUT);
> +#endif
> + virtqueue_kick(vq);
> +
> + while (!list_empty(&viommu->requests)) {
> + len = 0;
> + req = virtqueue_get_buf(vq, &len);
> + if (req == NULL) {
> + if (!timeout || ktime_before(ktime_get(), timeout))
> + continue;
> +
> + /* After timeout, remove all requests */
> + req = list_first_entry(&viommu->requests,
> + struct viommu_request, list);
> + ret = -ETIMEDOUT;
> + }
> +
> + if (!len)
> + viommu_set_req_status(req->buf, req->len,
> + VIRTIO_IOMMU_S_IOERR);
> +
> + write_len = req->len - req->write_offset;
> + if (req->writeback && len >= write_len)
> + memcpy(req->writeback, req->buf + req->write_offset,
> + write_len);
> +
> + list_del(&req->list);
> + kfree(req);
So with DEBUG set, this will actually free memory that device still
DMA's into. Hardly pretty. I think you want to mark device broken,
queue the request and then wait for device to be reset.
> + }
> +
> + return ret;
> +}
> +
> +static int viommu_sync_req(struct viommu_dev *viommu)
> +{
> + int ret;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&viommu->request_lock, flags);
> + ret = __viommu_sync_req(viommu);
> + if (ret)
> + dev_dbg(viommu->dev, "could not sync requests (%d)\n", ret);
> + spin_unlock_irqrestore(&viommu->request_lock, flags);
> +
> + return ret;
> +}
> +
> +/*
> + * __viommu_add_request - Add one request to the queue
> + * @buf: pointer to the request buffer
> + * @len: length of the request buffer
> + * @writeback: copy data back to the buffer when the request completes.
> + *
> + * Add a request to the queue. Only synchronize the queue if it's already full.
> + * Otherwise don't kick the queue nor wait for requests to complete.
> + *
> + * When @writeback is true, data written by the device, including the request
> + * status, is copied into @buf after the request completes. This is unsafe if
> + * the caller allocates @buf on stack and drops the lock between add_req() and
> + * sync_req().
> + *
> + * Return 0 if the request was successfully added to the queue.
> + */
> +static int __viommu_add_req(struct viommu_dev *viommu, void *buf, size_t len,
> + bool writeback)
> +{
> + int ret;
> + off_t write_offset;
> + struct viommu_request *req;
> + struct scatterlist top_sg, bottom_sg;
> + struct scatterlist *sg[2] = { &top_sg, &bottom_sg };
> + struct virtqueue *vq = viommu->vqs[VIOMMU_REQUEST_VQ];
> +
> + assert_spin_locked(&viommu->request_lock);
> +
> + write_offset = viommu_get_req_offset(viommu, buf, len);
> + if (!write_offset)
> + return -EINVAL;
> +
> + req = kzalloc(sizeof(*req) + len, GFP_ATOMIC);
> + if (!req)
> + return -ENOMEM;
> +
> + req->len = len;
> + if (writeback) {
> + req->writeback = buf + write_offset;
> + req->write_offset = write_offset;
> + }
> + memcpy(&req->buf, buf, write_offset);
> +
> + sg_init_one(&top_sg, req->buf, write_offset);
> + sg_init_one(&bottom_sg, req->buf + write_offset, len - write_offset);
> +
> + ret = virtqueue_add_sgs(vq, sg, 1, 1, req, GFP_ATOMIC);
> + if (ret == -ENOSPC) {
> + /* If the queue is full, sync and retry */
> + if (!__viommu_sync_req(viommu))
> + ret = virtqueue_add_sgs(vq, sg, 1, 1, req, GFP_ATOMIC);
> + }
> + if (ret)
> + goto err_free;
> +
> + list_add_tail(&req->list, &viommu->requests);
> + return 0;
> +
> +err_free:
> + kfree(req);
> + return ret;
> +}
> +
> +static int viommu_add_req(struct viommu_dev *viommu, void *buf, size_t len)
> +{
> + int ret;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&viommu->request_lock, flags);
> + ret = __viommu_add_req(viommu, buf, len, false);
> + if (ret)
> + dev_dbg(viommu->dev, "could not add request: %d\n", ret);
> + spin_unlock_irqrestore(&viommu->request_lock, flags);
> +
> + return ret;
> +}
> +
> +/*
> + * Send a request and wait for it to complete. Return the request status (as an
> + * errno)
> + */
> +static int viommu_send_req_sync(struct viommu_dev *viommu, void *buf,
> + size_t len)
> +{
> + int ret;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&viommu->request_lock, flags);
> +
> + ret = __viommu_add_req(viommu, buf, len, true);
> + if (ret) {
> + dev_dbg(viommu->dev, "could not add request (%d)\n", ret);
> + goto out_unlock;
> + }
> +
> + ret = __viommu_sync_req(viommu);
> + if (ret) {
> + dev_dbg(viommu->dev, "could not sync requests (%d)\n", ret);
> + /* Fall-through (get the actual request status) */
> + }
> +
> + ret = viommu_get_req_errno(buf, len);
> +out_unlock:
> + spin_unlock_irqrestore(&viommu->request_lock, flags);
> + return ret;
> +}
> +
> +/*
> + * viommu_add_mapping - add a mapping to the internal tree
> + *
> + * On success, return the new mapping. Otherwise return NULL.
> + */
> +static struct viommu_mapping *
> +viommu_add_mapping(struct viommu_domain *vdomain, unsigned long iova,
> + phys_addr_t paddr, size_t size, u32 flags)
> +{
> + unsigned long irqflags;
> + struct viommu_mapping *mapping;
> +
> + mapping = kzalloc(sizeof(*mapping), GFP_ATOMIC);
> + if (!mapping)
> + return NULL;
> +
> + mapping->paddr = paddr;
> + mapping->iova.start = iova;
> + mapping->iova.last = iova + size - 1;
> + mapping->flags = flags;
> +
> + spin_lock_irqsave(&vdomain->mappings_lock, irqflags);
> + interval_tree_insert(&mapping->iova, &vdomain->mappings);
> + spin_unlock_irqrestore(&vdomain->mappings_lock, irqflags);
> +
> + return mapping;
> +}
> +
> +/*
> + * viommu_del_mappings - remove mappings from the internal tree
> + *
> + * @vdomain: the domain
> + * @iova: start of the range
> + * @size: size of the range. A size of 0 corresponds to the entire address
> + * space.
> + *
> + * On success, returns the number of unmapped bytes (>= size)
> + */
> +static size_t viommu_del_mappings(struct viommu_domain *vdomain,
> + unsigned long iova, size_t size)
> +{
> + size_t unmapped = 0;
> + unsigned long flags;
> + unsigned long last = iova + size - 1;
> + struct viommu_mapping *mapping = NULL;
> + struct interval_tree_node *node, *next;
> +
> + spin_lock_irqsave(&vdomain->mappings_lock, flags);
> + next = interval_tree_iter_first(&vdomain->mappings, iova, last);
> + while (next) {
> + node = next;
> + mapping = container_of(node, struct viommu_mapping, iova);
> + next = interval_tree_iter_next(node, iova, last);
> +
> + /* Trying to split a mapping? */
> + if (mapping->iova.start < iova)
> + break;
> +
> + /*
> + * Note that for a partial range, this will return the full
> + * mapping so we avoid sending split requests to the device.
> + */
> + unmapped += mapping->iova.last - mapping->iova.start + 1;
> +
> + interval_tree_remove(node, &vdomain->mappings);
> + kfree(mapping);
> + }
> + spin_unlock_irqrestore(&vdomain->mappings_lock, flags);
> +
> + return unmapped;
> +}
> +
> +/*
> + * viommu_replay_mappings - re-send MAP requests
> + *
> + * When reattaching a domain that was previously detached from all endpoints,
> + * mappings were deleted from the device. Re-create the mappings available in
> + * the internal tree.
> + */
> +static int viommu_replay_mappings(struct viommu_domain *vdomain)
> +{
> + int ret;
> + unsigned long flags;
> + struct viommu_mapping *mapping;
> + struct interval_tree_node *node;
> + struct virtio_iommu_req_map map;
> +
> + spin_lock_irqsave(&vdomain->mappings_lock, flags);
> + node = interval_tree_iter_first(&vdomain->mappings, 0, -1UL);
> + while (node) {
> + mapping = container_of(node, struct viommu_mapping, iova);
> + map = (struct virtio_iommu_req_map) {
> + .head.type = VIRTIO_IOMMU_T_MAP,
> + .domain = cpu_to_le32(vdomain->id),
> + .virt_start = cpu_to_le64(mapping->iova.start),
> + .virt_end = cpu_to_le64(mapping->iova.last),
> + .phys_start = cpu_to_le64(mapping->paddr),
> + .flags = cpu_to_le32(mapping->flags),
> + };
> +
> + ret = viommu_send_req_sync(vdomain->viommu, &map, sizeof(map));
> + if (ret)
> + break;
> +
> + node = interval_tree_iter_next(node, 0, -1UL);
> + }
> + spin_unlock_irqrestore(&vdomain->mappings_lock, flags);
> +
> + return ret;
> +}
> +
> +/* IOMMU API */
> +
> +static struct iommu_domain *viommu_domain_alloc(unsigned type)
> +{
> + struct viommu_domain *vdomain;
> +
> + if (type != IOMMU_DOMAIN_UNMANAGED && type != IOMMU_DOMAIN_DMA)
> + return NULL;
> +
> + vdomain = kzalloc(sizeof(*vdomain), GFP_KERNEL);
> + if (!vdomain)
> + return NULL;
> +
> + mutex_init(&vdomain->mutex);
> + spin_lock_init(&vdomain->mappings_lock);
> + vdomain->mappings = RB_ROOT_CACHED;
> +
> + if (type == IOMMU_DOMAIN_DMA &&
> + iommu_get_dma_cookie(&vdomain->domain)) {
> + kfree(vdomain);
> + return NULL;
> + }
> +
> + return &vdomain->domain;
> +}
> +
> +static int viommu_domain_finalise(struct viommu_dev *viommu,
> + struct iommu_domain *domain)
> +{
> + int ret;
> + struct viommu_domain *vdomain = to_viommu_domain(domain);
> + unsigned int max_domain = viommu->domain_bits > 31 ? ~0 :
> + (1U << viommu->domain_bits) - 1;
> +
> + vdomain->viommu = viommu;
> +
> + domain->pgsize_bitmap = viommu->pgsize_bitmap;
> + domain->geometry = viommu->geometry;
> +
> + ret = ida_alloc_max(&viommu->domain_ids, max_domain, GFP_KERNEL);
> + if (ret >= 0)
> + vdomain->id = (unsigned int)ret;
> +
> + return ret > 0 ? 0 : ret;
> +}
> +
> +static void viommu_domain_free(struct iommu_domain *domain)
> +{
> + struct viommu_domain *vdomain = to_viommu_domain(domain);
> +
> + iommu_put_dma_cookie(domain);
> +
> + /* Free all remaining mappings (size 2^64) */
> + viommu_del_mappings(vdomain, 0, 0);
> +
> + if (vdomain->viommu)
> + ida_free(&vdomain->viommu->domain_ids, vdomain->id);
> +
> + kfree(vdomain);
> +}
> +
> +static int viommu_attach_dev(struct iommu_domain *domain, struct device *dev)
> +{
> + int i;
> + int ret = 0;
> + struct virtio_iommu_req_attach req;
> + struct iommu_fwspec *fwspec = dev->iommu_fwspec;
> + struct viommu_endpoint *vdev = fwspec->iommu_priv;
> + struct viommu_domain *vdomain = to_viommu_domain(domain);
> +
> + mutex_lock(&vdomain->mutex);
> + if (!vdomain->viommu) {
> + /*
> + * Initialize the domain proper now that we know which viommu
> + * owns it.
> + */
> + ret = viommu_domain_finalise(vdev->viommu, domain);
> + } else if (vdomain->viommu != vdev->viommu) {
> + dev_err(dev, "cannot attach to foreign vIOMMU\n");
> + ret = -EXDEV;
> + }
> + mutex_unlock(&vdomain->mutex);
> +
> + if (ret)
> + return ret;
> +
> + /*
> + * In the virtio-iommu device, when attaching the endpoint to a new
> + * domain, it is detached from the old one and, if as as a result the
> + * old domain isn't attached to any endpoint, all mappings are removed
> + * from the old domain and it is freed.
> + *
> + * In the driver the old domain still exists, and its mappings will be
> + * recreated if it gets reattached to an endpoint. Otherwise it will be
> + * freed explicitly.
> + *
> + * vdev->vdomain is protected by group->mutex
> + */
> + if (vdev->vdomain)
> + vdev->vdomain->nr_endpoints--;
> +
> + req = (struct virtio_iommu_req_attach) {
> + .head.type = VIRTIO_IOMMU_T_ATTACH,
> + .domain = cpu_to_le32(vdomain->id),
> + };
> +
> + for (i = 0; i < fwspec->num_ids; i++) {
> + req.endpoint = cpu_to_le32(fwspec->ids[i]);
> +
> + ret = viommu_send_req_sync(vdomain->viommu, &req, sizeof(req));
> + if (ret)
> + return ret;
> + }
> +
> + if (!vdomain->nr_endpoints) {
> + /*
> + * This endpoint is the first to be attached to the domain.
> + * Replay existing mappings (e.g. SW MSI).
> + */
> + ret = viommu_replay_mappings(vdomain);
> + if (ret)
> + return ret;
> + }
> +
> + vdomain->nr_endpoints++;
> + vdev->vdomain = vdomain;
> +
> + return 0;
> +}
> +
> +static int viommu_map(struct iommu_domain *domain, unsigned long iova,
> + phys_addr_t paddr, size_t size, int prot)
> +{
> + int ret;
> + int flags;
> + struct viommu_mapping *mapping;
> + struct virtio_iommu_req_map map;
> + struct viommu_domain *vdomain = to_viommu_domain(domain);
> +
> + flags = (prot & IOMMU_READ ? VIRTIO_IOMMU_MAP_F_READ : 0) |
> + (prot & IOMMU_WRITE ? VIRTIO_IOMMU_MAP_F_WRITE : 0) |
> + (prot & IOMMU_MMIO ? VIRTIO_IOMMU_MAP_F_MMIO : 0);
> +
> + mapping = viommu_add_mapping(vdomain, iova, paddr, size, flags);
> + if (!mapping)
> + return -ENOMEM;
> +
> + map = (struct virtio_iommu_req_map) {
> + .head.type = VIRTIO_IOMMU_T_MAP,
> + .domain = cpu_to_le32(vdomain->id),
> + .virt_start = cpu_to_le64(iova),
> + .phys_start = cpu_to_le64(paddr),
> + .virt_end = cpu_to_le64(iova + size - 1),
> + .flags = cpu_to_le32(flags),
> + };
> +
> + if (!vdomain->nr_endpoints)
> + return 0;
> +
> + ret = viommu_send_req_sync(vdomain->viommu, &map, sizeof(map));
> + if (ret)
> + viommu_del_mappings(vdomain, iova, size);
> +
> + return ret;
> +}
> +
> +static size_t viommu_unmap(struct iommu_domain *domain, unsigned long iova,
> + size_t size)
> +{
> + int ret = 0;
> + size_t unmapped;
> + struct virtio_iommu_req_unmap unmap;
> + struct viommu_domain *vdomain = to_viommu_domain(domain);
> +
> + unmapped = viommu_del_mappings(vdomain, iova, size);
> + if (unmapped < size)
> + return 0;
> +
> + /* Device already removed all mappings after detach. */
> + if (!vdomain->nr_endpoints)
> + return unmapped;
> +
> + unmap = (struct virtio_iommu_req_unmap) {
> + .head.type = VIRTIO_IOMMU_T_UNMAP,
> + .domain = cpu_to_le32(vdomain->id),
> + .virt_start = cpu_to_le64(iova),
> + .virt_end = cpu_to_le64(iova + unmapped - 1),
> + };
> +
> + ret = viommu_add_req(vdomain->viommu, &unmap, sizeof(unmap));
> + return ret ? 0 : unmapped;
> +}
> +
> +static phys_addr_t viommu_iova_to_phys(struct iommu_domain *domain,
> + dma_addr_t iova)
> +{
> + u64 paddr = 0;
> + unsigned long flags;
> + struct viommu_mapping *mapping;
> + struct interval_tree_node *node;
> + struct viommu_domain *vdomain = to_viommu_domain(domain);
> +
> + spin_lock_irqsave(&vdomain->mappings_lock, flags);
> + node = interval_tree_iter_first(&vdomain->mappings, iova, iova);
> + if (node) {
> + mapping = container_of(node, struct viommu_mapping, iova);
> + paddr = mapping->paddr + (iova - mapping->iova.start);
> + }
> + spin_unlock_irqrestore(&vdomain->mappings_lock, flags);
> +
> + return paddr;
> +}
> +
> +static void viommu_iotlb_sync(struct iommu_domain *domain)
> +{
> + struct viommu_domain *vdomain = to_viommu_domain(domain);
> +
> + viommu_sync_req(vdomain->viommu);
> +}
> +
> +static void viommu_get_resv_regions(struct device *dev, struct list_head *head)
> +{
> + struct iommu_resv_region *region;
> + int prot = IOMMU_WRITE | IOMMU_NOEXEC | IOMMU_MMIO;
> +
> + region = iommu_alloc_resv_region(MSI_IOVA_BASE, MSI_IOVA_LENGTH, prot,
> + IOMMU_RESV_SW_MSI);
> + if (!region)
> + return;
> +
> + list_add_tail(®ion->list, head);
> + iommu_dma_get_resv_regions(dev, head);
> +}
> +
> +static void viommu_put_resv_regions(struct device *dev, struct list_head *head)
> +{
> + struct iommu_resv_region *entry, *next;
> +
> + list_for_each_entry_safe(entry, next, head, list)
> + kfree(entry);
> +}
> +
> +static struct iommu_ops viommu_ops;
> +static struct virtio_driver virtio_iommu_drv;
> +
> +static int viommu_match_node(struct device *dev, void *data)
> +{
> + return dev->parent->fwnode == data;
> +}
> +
> +static struct viommu_dev *viommu_get_by_fwnode(struct fwnode_handle *fwnode)
> +{
> + struct device *dev = driver_find_device(&virtio_iommu_drv.driver, NULL,
> + fwnode, viommu_match_node);
> + put_device(dev);
> +
> + return dev ? dev_to_virtio(dev)->priv : NULL;
> +}
> +
> +static int viommu_add_device(struct device *dev)
> +{
> + int ret;
> + struct iommu_group *group;
> + struct viommu_endpoint *vdev;
> + struct viommu_dev *viommu = NULL;
> + struct iommu_fwspec *fwspec = dev->iommu_fwspec;
> +
> + if (!fwspec || fwspec->ops != &viommu_ops)
> + return -ENODEV;
> +
> + viommu = viommu_get_by_fwnode(fwspec->iommu_fwnode);
> + if (!viommu)
> + return -ENODEV;
> +
> + vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
> + if (!vdev)
> + return -ENOMEM;
> +
> + vdev->viommu = viommu;
> + fwspec->iommu_priv = vdev;
> +
> + ret = iommu_device_link(&viommu->iommu, dev);
> + if (ret)
> + goto err_free_dev;
> +
> + /*
> + * Last step creates a default domain and attaches to it. Everything
> + * must be ready.
> + */
> + group = iommu_group_get_for_dev(dev);
> + if (IS_ERR(group)) {
> + ret = PTR_ERR(group);
> + goto err_unlink_dev;
> + }
> +
> + iommu_group_put(group);
> +
> + return PTR_ERR_OR_ZERO(group);
> +
> +err_unlink_dev:
> + iommu_device_unlink(&viommu->iommu, dev);
> +
> +err_free_dev:
> + kfree(vdev);
> +
> + return ret;
> +}
> +
> +static void viommu_remove_device(struct device *dev)
> +{
> + struct viommu_endpoint *vdev;
> + struct iommu_fwspec *fwspec = dev->iommu_fwspec;
> +
> + if (!fwspec || fwspec->ops != &viommu_ops)
> + return;
> +
> + vdev = fwspec->iommu_priv;
> +
> + iommu_group_remove_device(dev);
> + iommu_device_unlink(&vdev->viommu->iommu, dev);
> + kfree(vdev);
> +}
> +
> +static struct iommu_group *viommu_device_group(struct device *dev)
> +{
> + if (dev_is_pci(dev))
> + return pci_device_group(dev);
> + else
> + return generic_device_group(dev);
> +}
> +
> +static int viommu_of_xlate(struct device *dev, struct of_phandle_args *args)
> +{
> + return iommu_fwspec_add_ids(dev, args->args, 1);
> +}
> +
> +static struct iommu_ops viommu_ops = {
> + .domain_alloc = viommu_domain_alloc,
> + .domain_free = viommu_domain_free,
> + .attach_dev = viommu_attach_dev,
> + .map = viommu_map,
> + .unmap = viommu_unmap,
> + .iova_to_phys = viommu_iova_to_phys,
> + .iotlb_sync = viommu_iotlb_sync,
> + .add_device = viommu_add_device,
> + .remove_device = viommu_remove_device,
> + .device_group = viommu_device_group,
> + .get_resv_regions = viommu_get_resv_regions,
> + .put_resv_regions = viommu_put_resv_regions,
> + .of_xlate = viommu_of_xlate,
> +};
> +
> +static int viommu_init_vqs(struct viommu_dev *viommu)
> +{
> + struct virtio_device *vdev = dev_to_virtio(viommu->dev);
> + const char *name = "request";
> + void *ret;
> +
> + ret = virtio_find_single_vq(vdev, NULL, name);
> + if (IS_ERR(ret)) {
> + dev_err(viommu->dev, "cannot find VQ\n");
> + return PTR_ERR(ret);
> + }
> +
> + viommu->vqs[VIOMMU_REQUEST_VQ] = ret;
> +
> + return 0;
> +}
> +
> +static int viommu_probe(struct virtio_device *vdev)
> +{
> + struct device *parent_dev = vdev->dev.parent;
> + struct viommu_dev *viommu = NULL;
> + struct device *dev = &vdev->dev;
> + u64 input_start = 0;
> + u64 input_end = -1UL;
> + int ret;
> +
> + if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1))
> + return -ENODEV;
I'm a bit confused about what will happen if this device
happens to be behind an iommu itself.
If we can't handle that, should we clear PLATFORM_IOMMU
e.g. like the balloon does?
> +
> + viommu = devm_kzalloc(dev, sizeof(*viommu), GFP_KERNEL);
> + if (!viommu)
> + return -ENOMEM;
> +
> + spin_lock_init(&viommu->request_lock);
> + ida_init(&viommu->domain_ids);
> + viommu->dev = dev;
> + viommu->vdev = vdev;
> + INIT_LIST_HEAD(&viommu->requests);
> +
> + ret = viommu_init_vqs(viommu);
> + if (ret)
> + return ret;
> +
> + virtio_cread(vdev, struct virtio_iommu_config, page_size_mask,
> + &viommu->pgsize_bitmap);
> +
> + if (!viommu->pgsize_bitmap) {
> + ret = -EINVAL;
> + goto err_free_vqs;
> + }
> +
> + viommu->domain_bits = 32;
> +
> + /* Optional features */
> + virtio_cread_feature(vdev, VIRTIO_IOMMU_F_INPUT_RANGE,
> + struct virtio_iommu_config, input_range.start,
> + &input_start);
> +
> + virtio_cread_feature(vdev, VIRTIO_IOMMU_F_INPUT_RANGE,
> + struct virtio_iommu_config, input_range.end,
> + &input_end);
> +
> + virtio_cread_feature(vdev, VIRTIO_IOMMU_F_DOMAIN_BITS,
> + struct virtio_iommu_config, domain_bits,
> + &viommu->domain_bits);
> +
> + viommu->geometry = (struct iommu_domain_geometry) {
> + .aperture_start = input_start,
> + .aperture_end = input_end,
> + .force_aperture = true,
> + };
> +
> + viommu_ops.pgsize_bitmap = viommu->pgsize_bitmap;
> +
> + virtio_device_ready(vdev);
> +
> + ret = iommu_device_sysfs_add(&viommu->iommu, dev, NULL, "%s",
> + virtio_bus_name(vdev));
> + if (ret)
> + goto err_free_vqs;
> +
> + iommu_device_set_ops(&viommu->iommu, &viommu_ops);
> + iommu_device_set_fwnode(&viommu->iommu, parent_dev->fwnode);
> +
> + iommu_device_register(&viommu->iommu);
> +
> +#ifdef CONFIG_PCI
> + if (pci_bus_type.iommu_ops != &viommu_ops) {
> + pci_request_acs();
> + ret = bus_set_iommu(&pci_bus_type, &viommu_ops);
> + if (ret)
> + goto err_unregister;
> + }
> +#endif
> +#ifdef CONFIG_ARM_AMBA
> + if (amba_bustype.iommu_ops != &viommu_ops) {
> + ret = bus_set_iommu(&amba_bustype, &viommu_ops);
> + if (ret)
> + goto err_unregister;
> + }
> +#endif
> + if (platform_bus_type.iommu_ops != &viommu_ops) {
> + ret = bus_set_iommu(&platform_bus_type, &viommu_ops);
> + if (ret)
> + goto err_unregister;
> + }
> +
> + vdev->priv = viommu;
> +
> + dev_info(dev, "input address: %u bits\n",
> + order_base_2(viommu->geometry.aperture_end));
> + dev_info(dev, "page mask: %#llx\n", viommu->pgsize_bitmap);
> +
> + return 0;
> +
> +err_unregister:
> + iommu_device_sysfs_remove(&viommu->iommu);
> + iommu_device_unregister(&viommu->iommu);
> +err_free_vqs:
> + vdev->config->del_vqs(vdev);
> +
> + return ret;
> +}
> +
> +static void viommu_remove(struct virtio_device *vdev)
> +{
> + struct viommu_dev *viommu = vdev->priv;
> +
> + iommu_device_sysfs_remove(&viommu->iommu);
> + iommu_device_unregister(&viommu->iommu);
> +
> + /* Stop all virtqueues */
> + vdev->config->reset(vdev);
> + vdev->config->del_vqs(vdev);
> +
> + dev_info(&vdev->dev, "device removed\n");
> +}
> +
> +static void viommu_config_changed(struct virtio_device *vdev)
> +{
> + dev_warn(&vdev->dev, "config changed\n");
> +}
> +
> +static unsigned int features[] = {
> + VIRTIO_IOMMU_F_MAP_UNMAP,
> + VIRTIO_IOMMU_F_DOMAIN_BITS,
> + VIRTIO_IOMMU_F_INPUT_RANGE,
> +};
> +
> +static struct virtio_device_id id_table[] = {
> + { VIRTIO_ID_IOMMU, VIRTIO_DEV_ANY_ID },
> + { 0 },
> +};
> +
> +static struct virtio_driver virtio_iommu_drv = {
> + .driver.name = KBUILD_MODNAME,
> + .driver.owner = THIS_MODULE,
> + .id_table = id_table,
> + .feature_table = features,
> + .feature_table_size = ARRAY_SIZE(features),
> + .probe = viommu_probe,
> + .remove = viommu_remove,
> + .config_changed = viommu_config_changed,
> +};
> +
> +module_virtio_driver(virtio_iommu_drv);
> +
> +MODULE_DESCRIPTION("Virtio IOMMU driver");
> +MODULE_AUTHOR("Jean-Philippe Brucker <jean-philippe.brucker@xxxxxxx>");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/uapi/linux/virtio_ids.h b/include/uapi/linux/virtio_ids.h
> index 6d5c3b2d4f4d..cfe47c5d9a56 100644
> --- a/include/uapi/linux/virtio_ids.h
> +++ b/include/uapi/linux/virtio_ids.h
> @@ -43,5 +43,6 @@
> #define VIRTIO_ID_INPUT 18 /* virtio input */
> #define VIRTIO_ID_VSOCK 19 /* virtio vsock transport */
> #define VIRTIO_ID_CRYPTO 20 /* virtio crypto */
> +#define VIRTIO_ID_IOMMU 23 /* virtio IOMMU */
>
> #endif /* _LINUX_VIRTIO_IDS_H */
> diff --git a/include/uapi/linux/virtio_iommu.h b/include/uapi/linux/virtio_iommu.h
> new file mode 100644
> index 000000000000..e808fc7fbe82
> --- /dev/null
> +++ b/include/uapi/linux/virtio_iommu.h
> @@ -0,0 +1,101 @@
> +/* SPDX-License-Identifier: BSD-3-Clause */
> +/*
> + * Virtio-iommu definition v0.8
> + *
> + * Copyright (C) 2018 Arm Ltd.
> + */
> +#ifndef _UAPI_LINUX_VIRTIO_IOMMU_H
> +#define _UAPI_LINUX_VIRTIO_IOMMU_H
> +
> +#include <linux/types.h>
> +
> +/* Feature bits */
> +#define VIRTIO_IOMMU_F_INPUT_RANGE 0
> +#define VIRTIO_IOMMU_F_DOMAIN_BITS 1
> +#define VIRTIO_IOMMU_F_MAP_UNMAP 2
> +#define VIRTIO_IOMMU_F_BYPASS 3
> +
> +struct virtio_iommu_config {
> + /* Supported page sizes */
> + __u64 page_size_mask;
> + /* Supported IOVA range */
> + struct virtio_iommu_range {
I'd rather we moved the definition outside even though gcc allows it -
some old userspace compilers might not.
> + __u64 start;
> + __u64 end;
> + } input_range;
> + /* Max domain ID size */
> + __u8 domain_bits;
Let's add explicit padding here as well?
> +};
> +
> +/* Request types */
> +#define VIRTIO_IOMMU_T_ATTACH 0x01
> +#define VIRTIO_IOMMU_T_DETACH 0x02
> +#define VIRTIO_IOMMU_T_MAP 0x03
> +#define VIRTIO_IOMMU_T_UNMAP 0x04
> +
> +/* Status types */
> +#define VIRTIO_IOMMU_S_OK 0x00
> +#define VIRTIO_IOMMU_S_IOERR 0x01
> +#define VIRTIO_IOMMU_S_UNSUPP 0x02
> +#define VIRTIO_IOMMU_S_DEVERR 0x03
> +#define VIRTIO_IOMMU_S_INVAL 0x04
> +#define VIRTIO_IOMMU_S_RANGE 0x05
> +#define VIRTIO_IOMMU_S_NOENT 0x06
> +#define VIRTIO_IOMMU_S_FAULT 0x07
> +
> +struct virtio_iommu_req_head {
> + __u8 type;
> + __u8 reserved[3];
> +};
> +
> +struct virtio_iommu_req_tail {
> + __u8 status;
> + __u8 reserved[3];
> +};
> +
> +struct virtio_iommu_req_attach {
> + struct virtio_iommu_req_head head;
> + __le32 domain;
> + __le32 endpoint;
> + __u8 reserved[8];
> + struct virtio_iommu_req_tail tail;
> +};
> +
> +struct virtio_iommu_req_detach {
> + struct virtio_iommu_req_head head;
> + __le32 domain;
> + __le32 endpoint;
> + __u8 reserved[8];
> + struct virtio_iommu_req_tail tail;
> +};
> +
> +#define VIRTIO_IOMMU_MAP_F_READ (1 << 0)
> +#define VIRTIO_IOMMU_MAP_F_WRITE (1 << 1)
> +#define VIRTIO_IOMMU_MAP_F_EXEC (1 << 2)
> +#define VIRTIO_IOMMU_MAP_F_MMIO (1 << 3)
> +
> +#define VIRTIO_IOMMU_MAP_F_MASK (VIRTIO_IOMMU_MAP_F_READ | \
> + VIRTIO_IOMMU_MAP_F_WRITE | \
> + VIRTIO_IOMMU_MAP_F_EXEC | \
> + VIRTIO_IOMMU_MAP_F_MMIO)
> +
> +struct virtio_iommu_req_map {
> + struct virtio_iommu_req_head head;
> + __le32 domain;
> + __le64 virt_start;
> + __le64 virt_end;
> + __le64 phys_start;
> + __le32 flags;
> + struct virtio_iommu_req_tail tail;
> +};
> +
> +struct virtio_iommu_req_unmap {
> + struct virtio_iommu_req_head head;
> + __le32 domain;
> + __le64 virt_start;
> + __le64 virt_end;
> + __u8 reserved[4];
> + struct virtio_iommu_req_tail tail;
> +};
> +
> +#endif
> --
> 2.19.1
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