Add two new ioctl for VFIO containers. VFIO_IOMMU_BIND_PROCESS creates a
bond between a container and a process address space, identified by a
device-specific ID named PASID. This allows the device to target DMA
transactions at the process virtual addresses without a need for mapping
and unmapping buffers explicitly in the IOMMU. The process page tables are
shared with the IOMMU, and mechanisms such as PCI ATS/PRI are used to
handle faults. VFIO_IOMMU_UNBIND_PROCESS removes a bond created with
VFIO_IOMMU_BIND_PROCESS.
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@xxxxxxx>
---
drivers/vfio/vfio_iommu_type1.c | 399 ++++++++++++++++++++++++++++++++++++++++
include/uapi/linux/vfio.h | 76 ++++++++
2 files changed, 475 insertions(+)
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index e30e29ae4819..cac066f0026b 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -30,6 +30,7 @@
#include <linux/iommu.h>
#include <linux/module.h>
#include <linux/mm.h>
+#include <linux/ptrace.h>
#include <linux/rbtree.h>
#include <linux/sched/signal.h>
#include <linux/sched/mm.h>
@@ -60,6 +61,7 @@ MODULE_PARM_DESC(disable_hugepages,
struct vfio_iommu {
struct list_head domain_list;
+ struct list_head mm_list;
struct vfio_domain *external_domain; /* domain for external user */
struct mutex lock;
struct rb_root dma_list;
@@ -90,6 +92,15 @@ struct vfio_dma {
struct vfio_group {
struct iommu_group *iommu_group;
struct list_head next;
+ bool sva_enabled;
+};
+
+struct vfio_mm {
+#define VFIO_PASID_INVALID (-1)
+ spinlock_t lock;
+ int pasid;
+ struct mm_struct *mm;
+ struct list_head next;
};
/*
@@ -1117,6 +1128,157 @@ static int vfio_iommu_replay(struct vfio_iommu *iommu,
return 0;
}
+static int vfio_iommu_mm_exit(struct device *dev, int pasid, void *data)
+{
+ struct vfio_mm *vfio_mm = data;
+
+ /*
+ * The mm_exit callback cannot block, so we can't take the iommu mutex
+ * and remove this vfio_mm from the list. Hopefully the SVA code will
+ * relax its locking requirement in the future.
+ *
+ * We mostly care about attach_group, which will attempt to replay all
+ * binds in this container. Ensure that it doesn't touch this defunct mm
+ * struct, by clearing the pointer. The structure will be freed when the
+ * group is removed from the container.
+ */
+ spin_lock(&vfio_mm->lock);
+ vfio_mm->mm = NULL;
+ spin_unlock(&vfio_mm->lock);
+
+ return 0;
+}
+
+static int vfio_iommu_sva_init(struct device *dev, void *data)
+{
+
+ int ret;
+
+ ret = iommu_sva_device_init(dev, IOMMU_SVA_FEAT_PASID |
+ IOMMU_SVA_FEAT_IOPF, 0);
+ if (ret)
+ return ret;
+
+ return iommu_register_mm_exit_handler(dev, vfio_iommu_mm_exit);
+}
+
+static int vfio_iommu_sva_shutdown(struct device *dev, void *data)
+{
+ iommu_sva_device_shutdown(dev);
+ iommu_unregister_mm_exit_handler(dev);
+
+ return 0;
+}
+
+static int vfio_iommu_bind_group(struct vfio_iommu *iommu,
+ struct vfio_group *group,
+ struct vfio_mm *vfio_mm)
+{
+ int ret;
+ int pasid;
+
+ if (!group->sva_enabled) {
+ ret = iommu_group_for_each_dev(group->iommu_group, NULL,
+ vfio_iommu_sva_init);
+ if (ret)
+ return ret;
+
+ group->sva_enabled = true;
+ }
+
+ ret = iommu_sva_bind_group(group->iommu_group, vfio_mm->mm, &pasid,
+ IOMMU_SVA_FEAT_PASID | IOMMU_SVA_FEAT_IOPF,
+ vfio_mm);
+ if (ret)
+ return ret;
+
+ if (WARN_ON(vfio_mm->pasid != VFIO_PASID_INVALID && pasid !=
+ vfio_mm->pasid))
+ return -EFAULT;
+
+ vfio_mm->pasid = pasid;
+
+ return 0;
+}
+
+static void vfio_iommu_unbind_group(struct vfio_group *group,
+ struct vfio_mm *vfio_mm)
+{
+ iommu_sva_unbind_group(group->iommu_group, vfio_mm->pasid);
+}
+
+static void vfio_iommu_unbind(struct vfio_iommu *iommu,
+ struct vfio_mm *vfio_mm)
+{
+ struct vfio_group *group;
+ struct vfio_domain *domain;
+
+ list_for_each_entry(domain, &iommu->domain_list, next)
+ list_for_each_entry(group, &domain->group_list, next)
+ vfio_iommu_unbind_group(group, vfio_mm);
+}
+
+static bool vfio_mm_get(struct vfio_mm *vfio_mm)
+{
+ bool ret;
+
+ spin_lock(&vfio_mm->lock);
+ ret = vfio_mm->mm && mmget_not_zero(vfio_mm->mm);
+ spin_unlock(&vfio_mm->lock);
+
+ return ret;
+}
+
+static void vfio_mm_put(struct vfio_mm *vfio_mm)
+{
+ mmput(vfio_mm->mm);
+}
+
+static int vfio_iommu_replay_bind(struct vfio_iommu *iommu, struct vfio_group *group)
+{
+ int ret = 0;
+ struct vfio_mm *vfio_mm;
+
+ list_for_each_entry(vfio_mm, &iommu->mm_list, next) {
+ /*
+ * Ensure mm doesn't exit while we're binding it to the new
+ * group.
+ */
+ if (!vfio_mm_get(vfio_mm))
+ continue;
+ ret = vfio_iommu_bind_group(iommu, group, vfio_mm);
+ vfio_mm_put(vfio_mm);
+
+ if (ret)
+ goto out_unbind;
+ }
+
+ return 0;
+
+out_unbind:
+ list_for_each_entry_continue_reverse(vfio_mm, &iommu->mm_list, next) {
+ if (!vfio_mm_get(vfio_mm))
+ continue;
+ iommu_sva_unbind_group(group->iommu_group, vfio_mm->pasid);
+ vfio_mm_put(vfio_mm);
+ }
+
+ return ret;
+}
+
+static void vfio_iommu_free_all_mm(struct vfio_iommu *iommu)
+{
+ struct vfio_mm *vfio_mm, *tmp;
+
+ /*
+ * No need for unbind() here. Since all groups are detached from this
+ * iommu, bonds have been removed.
+ */
+ list_for_each_entry_safe(vfio_mm, tmp, &iommu->mm_list, next)
+ kfree(vfio_mm);
+ INIT_LIST_HEAD(&iommu->mm_list);
+}
+
/*
* We change our unmap behavior slightly depending on whether the IOMMU
* supports fine-grained superpages. IOMMUs like AMD-Vi will use a superpage
@@ -1301,6 +1463,15 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
d->prot == domain->prot) {
iommu_detach_group(domain->domain, iommu_group);
if (!iommu_attach_group(d->domain, iommu_group)) {
+ if (vfio_iommu_replay_bind(iommu, group)) {
+ iommu_detach_group(d->domain, iommu_group);
+ ret = iommu_attach_group(domain->domain,
+ iommu_group);
+ if (ret)
+ goto out_domain;
+ continue;
+ }
+
list_add(&group->next, &d->group_list);
iommu_domain_free(domain->domain);
kfree(domain);
@@ -1321,6 +1492,10 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
if (ret)
goto out_detach;
+ ret = vfio_iommu_replay_bind(iommu, group);
+ if (ret)
+ goto out_detach;
+
if (resv_msi) {
ret = iommu_get_msi_cookie(domain->domain, resv_msi_base);
if (ret)
@@ -1426,6 +1601,11 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
continue;
iommu_detach_group(domain->domain, iommu_group);
+ if (group->sva_enabled) {
+ iommu_group_for_each_dev(iommu_group, NULL,
+ vfio_iommu_sva_shutdown);
+ group->sva_enabled = false;
+ }
list_del(&group->next);
kfree(group);
/*
@@ -1441,6 +1621,7 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
vfio_iommu_unmap_unpin_all(iommu);
else
vfio_iommu_unmap_unpin_reaccount(iommu);
+ vfio_iommu_free_all_mm(iommu);
}
iommu_domain_free(domain->domain);
list_del(&domain->next);
@@ -1475,6 +1656,7 @@ static void *vfio_iommu_type1_open(unsigned long arg)
}
INIT_LIST_HEAD(&iommu->domain_list);
+ INIT_LIST_HEAD(&iommu->mm_list);
iommu->dma_list = RB_ROOT;
mutex_init(&iommu->lock);
BLOCKING_INIT_NOTIFIER_HEAD(&iommu->notifier);
@@ -1509,6 +1691,7 @@ static void vfio_iommu_type1_release(void *iommu_data)
kfree(iommu->external_domain);
}
+ vfio_iommu_free_all_mm(iommu);
vfio_iommu_unmap_unpin_all(iommu);
list_for_each_entry_safe(domain, domain_tmp,
@@ -1537,6 +1720,184 @@ static int vfio_domains_have_iommu_cache(struct vfio_iommu *iommu)
return ret;
}
+static struct mm_struct *vfio_iommu_get_mm_by_vpid(pid_t vpid)
+{
+ struct mm_struct *mm;
+ struct task_struct *task;
+
+ rcu_read_lock();
+ task = find_task_by_vpid(vpid);
+ if (task)
+ get_task_struct(task);
+ rcu_read_unlock();
+ if (!task)
+ return ERR_PTR(-ESRCH);
+
+ /* Ensure that current has RW access on the mm */
+ mm = mm_access(task, PTRACE_MODE_ATTACH_REALCREDS);
+ put_task_struct(task);
+
+ if (!mm)
+ return ERR_PTR(-ESRCH);
+
+ return mm;
+}
+
+static long vfio_iommu_type1_bind_process(struct vfio_iommu *iommu,
+ void __user *arg,
+ struct vfio_iommu_type1_bind *bind)
+{
+ struct vfio_iommu_type1_bind_process params;
+ struct vfio_domain *domain;
+ struct vfio_group *group;
+ struct vfio_mm *vfio_mm;
+ struct mm_struct *mm;
+ unsigned long minsz;
+ int ret = 0;
+
+ minsz = sizeof(*bind) + sizeof(params);
+ if (bind->argsz < minsz)
+ return -EINVAL;
+
+ arg += sizeof(*bind);
+ if (copy_from_user(¶ms, arg, sizeof(params)))
+ return -EFAULT;
+
+ if (params.flags & ~VFIO_IOMMU_BIND_PID)
+ return -EINVAL;
+
+ if (params.flags & VFIO_IOMMU_BIND_PID) {
+ mm = vfio_iommu_get_mm_by_vpid(params.pid);
+ if (IS_ERR(mm))
+ return PTR_ERR(mm);
+ } else {
+ mm = get_task_mm(current);
+ if (!mm)
+ return -EINVAL;
+ }
+
+ mutex_lock(&iommu->lock);
+ if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu)) {
+ ret = -EINVAL;
+ goto out_put_mm;
+ }
+
+ list_for_each_entry(vfio_mm, &iommu->mm_list, next) {
+ if (vfio_mm->mm != mm)
+ continue;
+
+ params.pasid = vfio_mm->pasid;
+
+ ret = copy_to_user(arg, ¶ms, sizeof(params)) ? -EFAULT : 0;
+ goto out_put_mm;
+ }
+
+ vfio_mm = kzalloc(sizeof(*vfio_mm), GFP_KERNEL);
+ if (!vfio_mm) {
+ ret = -ENOMEM;
+ goto out_put_mm;
+ }
+
+ vfio_mm->mm = mm;
+ vfio_mm->pasid = VFIO_PASID_INVALID;
+ spin_lock_init(&vfio_mm->lock);
+
+ list_for_each_entry(domain, &iommu->domain_list, next) {
+ list_for_each_entry(group, &domain->group_list, next) {
+ ret = vfio_iommu_bind_group(iommu, group, vfio_mm);
+ if (ret)
+ break;
+ }
+ if (ret)
+ break;
+ }
+
+ if (ret) {
+ /* Undo all binds that already succeeded */
+ list_for_each_entry_continue_reverse(group, &domain->group_list,
+ next)
+ vfio_iommu_unbind_group(group, vfio_mm);
+ list_for_each_entry_continue_reverse(domain, &iommu->domain_list,
+ next)
+ list_for_each_entry(group, &domain->group_list, next)
+ vfio_iommu_unbind_group(group, vfio_mm);
+ kfree(vfio_mm);
+ } else {
+ list_add(&vfio_mm->next, &iommu->mm_list);
+
+ params.pasid = vfio_mm->pasid;
+ ret = copy_to_user(arg, ¶ms, sizeof(params)) ? -EFAULT : 0;
+ if (ret) {
+ vfio_iommu_unbind(iommu, vfio_mm);
+ kfree(vfio_mm);
+ }
+ }
+
+out_put_mm:
+ mutex_unlock(&iommu->lock);
+ mmput(mm);
+
+ return ret;
+}
+
+static long vfio_iommu_type1_unbind_process(struct vfio_iommu *iommu,
+ void __user *arg,
+ struct vfio_iommu_type1_bind *bind)
+{
+ int ret = -EINVAL;
+ unsigned long minsz;
+ struct mm_struct *mm;
+ struct vfio_mm *vfio_mm;
+ struct vfio_iommu_type1_bind_process params;
+
+ minsz = sizeof(*bind) + sizeof(params);
+ if (bind->argsz < minsz)
+ return -EINVAL;
+
+ arg += sizeof(*bind);
+ if (copy_from_user(¶ms, arg, sizeof(params)))
+ return -EFAULT;
+
+ if (params.flags & ~VFIO_IOMMU_BIND_PID)
+ return -EINVAL;
+
+ /*
+ * We can't simply unbind a foreign process by PASID, because the
+ * process might have died and the PASID might have been reallocated to
+ * another process. Instead we need to fetch that process mm by PID
+ * again to make sure we remove the right vfio_mm. In addition, holding
+ * the mm guarantees that mm_users isn't dropped while we unbind and the
+ * exit_mm handler doesn't fire. While not strictly necessary, not
+ * having to care about that race simplifies everyone's life.
+ */
+ if (params.flags & VFIO_IOMMU_BIND_PID) {
+ mm = vfio_iommu_get_mm_by_vpid(params.pid);
+ if (IS_ERR(mm))
+ return PTR_ERR(mm);
+ } else {
+ mm = get_task_mm(current);
+ if (!mm)
+ return -EINVAL;
+ }
+
+ ret = -ESRCH;
+ mutex_lock(&iommu->lock);
+ list_for_each_entry(vfio_mm, &iommu->mm_list, next) {
+ if (vfio_mm->mm != mm)
+ continue;
+
+ vfio_iommu_unbind(iommu, vfio_mm);
+ list_del(&vfio_mm->next);
+ kfree(vfio_mm);
+ ret = 0;
+ break;
+ }
+ mutex_unlock(&iommu->lock);
+ mmput(mm);
+
+ return ret;
+}
+
static long vfio_iommu_type1_ioctl(void *iommu_data,
unsigned int cmd, unsigned long arg)
{
@@ -1607,6 +1968,44 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
return copy_to_user((void __user *)arg, &unmap, minsz) ?
-EFAULT : 0;
+
+ } else if (cmd == VFIO_IOMMU_BIND) {
+ struct vfio_iommu_type1_bind bind;
+
+ minsz = offsetofend(struct vfio_iommu_type1_bind, mode);
+
+ if (copy_from_user(&bind, (void __user *)arg, minsz))
+ return -EFAULT;
+
+ if (bind.argsz < minsz)
+ return -EINVAL;
+
+ switch (bind.mode) {
+ case VFIO_IOMMU_BIND_PROCESS:
+ return vfio_iommu_type1_bind_process(iommu, (void *)arg,
+ &bind);
+ default:
+ return -EINVAL;
+ }
+
+ } else if (cmd == VFIO_IOMMU_UNBIND) {
+ struct vfio_iommu_type1_bind bind;
+
+ minsz = offsetofend(struct vfio_iommu_type1_bind, mode);
+
+ if (copy_from_user(&bind, (void __user *)arg, minsz))
+ return -EFAULT;
+
+ if (bind.argsz < minsz)
+ return -EINVAL;
+
+ switch (bind.mode) {
+ case VFIO_IOMMU_BIND_PROCESS:
+ return vfio_iommu_type1_unbind_process(iommu, (void *)arg,
+ &bind);
+ default:
+ return -EINVAL;
+ }
}
return -ENOTTY;
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index c74372163ed2..e1b9b8c58916 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -638,6 +638,82 @@ struct vfio_iommu_type1_dma_unmap {
#define VFIO_IOMMU_ENABLE _IO(VFIO_TYPE, VFIO_BASE + 15)
#define VFIO_IOMMU_DISABLE _IO(VFIO_TYPE, VFIO_BASE + 16)
+/*
+ * VFIO_IOMMU_BIND_PROCESS
+ *
+ * Allocate a PASID for a process address space, and use it to attach this
+ * process to all devices in the container. Devices can then tag their DMA
+ * traffic with the returned @pasid to perform transactions on the associated
+ * virtual address space. Mapping and unmapping buffers is performed by standard
+ * functions such as mmap and malloc.
+ *
+ * If flag is VFIO_IOMMU_BIND_PID, @pid contains the pid of a foreign process to
+ * bind. Otherwise the current task is bound. Given that the caller owns the
+ * device, setting this flag grants the caller read and write permissions on the
+ * entire address space of foreign process described by @pid. Therefore,
+ * permission to perform the bind operation on a foreign process is governed by
+ * the ptrace access mode PTRACE_MODE_ATTACH_REALCREDS check. See man ptrace(2)
+ * for more information.
+ *
+ * On success, VFIO writes a Process Address Space ID (PASID) into @pasid. This
+ * ID is unique to a process and can be used on all devices in the container.
+ *
+ * On fork, the child inherits the device fd and can use the bonds setup by its
+ * parent. Consequently, the child has R/W access on the address spaces bound by
+ * its parent. After an execv, the device fd is closed and the child doesn't
+ * have access to the address space anymore.
+ *
+ * To remove a bond between process and container, VFIO_IOMMU_UNBIND ioctl is
+ * issued with the same parameters. If a pid was specified in VFIO_IOMMU_BIND,
+ * it should also be present for VFIO_IOMMU_UNBIND. Otherwise unbind the current
+ * task from the container.
+ */
+struct vfio_iommu_type1_bind_process {
+ __u32 flags;
+#define VFIO_IOMMU_BIND_PID (1 << 0)
+ __u32 pasid;
+ __s32 pid;
+};
+
+/*
+ * Only mode supported at the moment is VFIO_IOMMU_BIND_PROCESS, which takes
+ * vfio_iommu_type1_bind_process in data.
+ */
+struct vfio_iommu_type1_bind {
+ __u32 argsz;
+ __u32 mode;
+#define VFIO_IOMMU_BIND_PROCESS (1 << 0)
+ __u8 data[];
+};
+
+/*
+ * VFIO_IOMMU_BIND - _IOWR(VFIO_TYPE, VFIO_BASE + 22, struct vfio_iommu_bind)
+ *
+ * Manage address spaces of devices in this container. Initially a TYPE1
+ * container can only have one address space, managed with
+ * VFIO_IOMMU_MAP/UNMAP_DMA.
+ *
+ * An IOMMU of type VFIO_TYPE1_NESTING_IOMMU can be managed by both MAP/UNMAP
+ * and BIND ioctls at the same time. MAP/UNMAP acts on the stage-2 (host) page
+ * tables, and BIND manages the stage-1 (guest) page tables. Other types of
+ * IOMMU may allow MAP/UNMAP and BIND to coexist, where MAP/UNMAP controls
+ * non-PASID traffic and BIND controls PASID traffic. But this depends on the
+ * underlying IOMMU architecture and isn't guaranteed.
+ *
+ * Availability of this feature depends on the device, its bus, the underlying
+ * IOMMU and the CPU architecture.
+ *
+ * returns: 0 on success, -errno on failure.
+ */
+#define VFIO_IOMMU_BIND _IO(VFIO_TYPE, VFIO_BASE + 22)
+
+/*
+ * VFIO_IOMMU_UNBIND - _IOWR(VFIO_TYPE, VFIO_BASE + 23, struct vfio_iommu_bind)
+ *
+ * Undo what was done by the corresponding VFIO_IOMMU_BIND ioctl.
+ */
+#define VFIO_IOMMU_UNBIND _IO(VFIO_TYPE, VFIO_BASE + 23)
+
/* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */
/*
--
2.15.1
