Hi Jean, On 11/15/18 5:52 PM, 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.Some few comments/questions below.> > Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker at arm.com> > --- > MAINTAINERS | 7 + > drivers/iommu/Kconfig | 11 + > drivers/iommu/Makefile | 1 + > drivers/iommu/virtio-iommu.c | 918 ++++++++++++++++++++++++++++++ > include/uapi/linux/virtio_ids.h | 1 + > include/uapi/linux/virtio_iommu.h | 104 ++++ > 6 files changed, 1042 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 0abecc528dac..0c7bdce57719 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -15948,6 +15948,13 @@ 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 at arm.com> > +L: virtualization at lists.linux-foundation.org > +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 at redhat.com> > M: Arnd Bergmann <arnd at arndb.de> > diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig > index d9a25715650e..efdeaaeee0e0 100644 > --- a/drivers/iommu/Kconfig > +++ b/drivers/iommu/Kconfig > @@ -435,4 +435,15 @@ 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 a158a68c8ea8..48d831a39281 100644 > --- a/drivers/iommu/Makefile > +++ b/drivers/iommu/Makefile > @@ -32,3 +32,4 @@ 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..2a9cb6285a1e > --- /dev/null > +++ b/drivers/iommu/virtio-iommu.c > @@ -0,0 +1,918 @@ > +// 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 > + > +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;same naming/comment as in smmu driver may help here struct mutex init_mutex; /* Protects viommu pointer */> + 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)nit: viommu_get_write_desc_offset would be more self-explanatory?> +{ > + 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; > + struct viommu_request *req; > + struct virtqueue *vq = viommu->vqs[VIOMMU_REQUEST_VQ]; > + > + assert_spin_locked(&viommu->request_lock); > + > + virtqueue_kick(vq); > + > + while (!list_empty(&viommu->requests)) { > + len = 0; > + req = virtqueue_get_buf(vq, &len); > + if (!req) > + continue; > + > + 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)I don't get "len >= write_len". Is it valid for the device to write more than write_len? If it writes less than write_len, the status is not set, is it?> + memcpy(req->writeback, req->buf + req->write_offset, > + write_len); > + > + list_del(&req->list); > + kfree(req); > + } > + > + 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)could be < 0 as well?> + 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. > + */This comment is not crystal clear to me, ie. why do we remove the entire node even if @size is less than mapping->iova.last - mapping->iova.start + 1.> + 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 = 0; > + 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)smmu drivers also support the IDENTITY type. Don't we want to support it as well?> + 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 viommuproperly initialize the domain now we know which viommu owns it? Thanks Eric> + * 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) || > + !virtio_has_feature(vdev, VIRTIO_IOMMU_F_MAP_UNMAP)) > + return -ENODEV; > + > + 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 at arm.com>"); > +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..2e0bf5792f26 > --- /dev/null > +++ b/include/uapi/linux/virtio_iommu.h > @@ -0,0 +1,104 @@ > +/* 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_range { > + __u64 start; > + __u64 end; > +}; > + > +struct virtio_iommu_config { > + /* Supported page sizes */ > + __u64 page_size_mask; > + /* Supported IOVA range */ > + struct virtio_iommu_range input_range; > + /* Max domain ID size */ > + __u8 domain_bits; > + __u8 padding[3]; > +}; > + > +/* 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 >
Hi Eric, On 16/11/2018 06:08, Auger Eric wrote:>> +struct viommu_domain { >> + struct iommu_domain domain; >> + struct viommu_dev *viommu; >> + struct mutex mutex; > same naming/comment as in smmu driver may help here > struct mutex init_mutex; /* Protects viommu pointer */ok>> + 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) > nit: viommu_get_write_desc_offset would be more self-explanatory?ok>> +{ >> + 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; >> + struct viommu_request *req; >> + struct virtqueue *vq = viommu->vqs[VIOMMU_REQUEST_VQ]; >> + >> + assert_spin_locked(&viommu->request_lock); >> + >> + virtqueue_kick(vq); >> + >> + while (!list_empty(&viommu->requests)) { >> + len = 0; >> + req = virtqueue_get_buf(vq, &len); >> + if (!req) >> + continue; >> + >> + 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) > I don't get "len >= write_len". Is it valid for the device to write more > than write_len? If it writes less than write_len, the status is not set, > is it?No on both counts, I'll change this to = There is a problem in the spec regarding this: to get the status, the driver expects the device to set len to the size of the whole writeable part of the buffer, even if it only filled a few properties. But the device doesn't have to do it at the moment. I need to change this sentence: The device MAY fill the remaining bytes of properties, if any, with zeroes. Into somthing like: The device SHOULD fill the remaining bytes of properties, if any, with zeroes. The QEMU and kvmtool devices already do this.>> + memcpy(req->writeback, req->buf + req->write_offset, >> + write_len); >> + >> + list_del(&req->list); >> + kfree(req); >> + } >> + >> + 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) > could be < 0 as well?Ah, yes [...]>> +/* >> + * 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. >> + */ > This comment is not crystal clear to me, ie. why do we remove the entire > node even if @size is less than mapping->iova.last - mapping->iova.start > + 1.The spec forbids splitting mappings (2.6.6 UNMAP request): (4) a = map(start=0, end=9); unmap(start=0, end=4) -> faults, doesn't unmap anything The rationale is that it complicates the implementation on both sides and probably isn't useful. It's also the VFIO semantics - if the host is VFIO, then UNMAP will return an error if you try to split a range like this. On the guest side though, passing a size smaller than what was mapped is valid, and the IOMMU API expects us to return the actual unmapped size. The guest VFIO driver tests this behavior in vfio_test_domain_fgsp(). I could also remove the "Trying to split a mapping" check above, which rejects things like: iommu_map(iova=0, sz=2) iommu_unmap(iova=1, sz=1) We could simply turn this into an UNMAP request for range [0, 1]. But I don't think we care at the moment. If the caller is the DMA API, then it requires the same dma_handle in alloc() and free(). If it is VFIO, then it rejects this kind of request from userspace.>> + 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 = 0; >> + 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) > smmu drivers also support the IDENTITY type. Don't we want to support it > as well?Eventually yes. The IDENTITY domain is useful when an IOMMU has been forced upon you and gets in the way of performance, in which case you get rid of it with CONFIG_IOMMU_DEFAULT_PASSTHROUGH=y or iommu.passthrough=y. For virtio-iommu though, you could simply not instantiate the device. I don't think it's difficult to add: if the device supports VIRTIO_IOMMU_F_BYPASS, then we simply don't send an ATTACH request. Otherwise after ATTACH we send a MAP for the whole input range. If the change isn't bigger than this, I'll add it to v5.>> + 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 > properly initialize the domain now we know which viommu owns it?Sure Thanks! Jean
Jean-Philippe Brucker
2018-Nov-20 17:30 UTC
[virtio-dev] Re: [PATCH v4 5/7] iommu: Add virtio-iommu driver
On 16/11/2018 18:46, Jean-Philippe Brucker wrote:>>> +/* >>> + * __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; >>> + struct viommu_request *req; >>> + struct virtqueue *vq = viommu->vqs[VIOMMU_REQUEST_VQ]; >>> + >>> + assert_spin_locked(&viommu->request_lock); >>> + >>> + virtqueue_kick(vq); >>> + >>> + while (!list_empty(&viommu->requests)) { >>> + len = 0; >>> + req = virtqueue_get_buf(vq, &len); >>> + if (!req) >>> + continue; >>> + >>> + 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) >> I don't get "len >= write_len". Is it valid for the device to write more >> than write_len? If it writes less than write_len, the status is not set, >> is it?Actually, len could well be three bytes smaller than write_len. The spec doesn't require the device to write the three padding bytes in virtio_iommu_req_tail, after the status byte. Here the driver just assumes that the device wrote the reserved field. The QEMU device seems to write uninitialized data in there... Any objection to changing the spec to require the device to initialize those bytes to zero? I think it makes things nicer overall and shouldn't have any performance impact. [...]>>> +static struct iommu_domain *viommu_domain_alloc(unsigned type) >>> +{ >>> + struct viommu_domain *vdomain; >>> + >>> + if (type != IOMMU_DOMAIN_UNMANAGED && type != IOMMU_DOMAIN_DMA) >> smmu drivers also support the IDENTITY type. Don't we want to support it >> as well? > > Eventually yes. The IDENTITY domain is useful when an IOMMU has been > forced upon you and gets in the way of performance, in which case you > get rid of it with CONFIG_IOMMU_DEFAULT_PASSTHROUGH=y or > iommu.passthrough=y. For virtio-iommu though, you could simply not > instantiate the device. > > I don't think it's difficult to add: if the device supports > VIRTIO_IOMMU_F_BYPASS, then we simply don't send an ATTACH request. > Otherwise after ATTACH we send a MAP for the whole input range. If the > change isn't bigger than this, I'll add it to v5.Not as straightforward as I hoped, when the device doesn't support VIRTIO_IOMMU_F_BYPASS: * We can't simply create an ID map for the whole input range, we need to carve out the resv_mem regions. * For a VFIO device, the host has no way of forwarding the identity mapping. For example the guest will attempt to map [0; 0xffffffffffff] -> [0; 0xffffffffffff], but VFIO only allows to map RAM and cannot take such request. One solution is to only create ID mapping for RAM, and register a notifier for memory hotplug, like intel-iommu does for IOMMUs that don't support HW pass-through. Since it's not completely trivial and - I think - not urgent, I'll leave this for later. Thanks, Jean