Re: [PATCH v4 02/26] iommu/sva: Manage process address spaces

Jonathan Cameron
2020-02-26T12:35:14Z

On Mon, 24 Feb 2020 19:23:37 +0100
Jean-Philippe Brucker <jean-philippe@linaro.org> wrote:

> From: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
>
> Add a small library to help IOMMU drivers manage process address spaces
> bound to their devices. Register an MMU notifier to track modification
> on each address space bound to one or more devices.
>
> IOMMU drivers must implement the io_mm_ops and can then use the helpers
> provided by this library to easily implement the SVA API introduced by
> commit 26b25a2b98e4. The io_mm_ops are:
>
> void *alloc(struct mm_struct *)
> Allocate a PASID context private to the IOMMU driver. There is a
> single context per mm. IOMMU drivers may perform arch-specific
> operations in there, for example pinning down a CPU ASID (on Arm).
>
> int attach(struct device *, int pasid, void *ctx, bool attach_domain)
> Attach a context to the device, by setting up the PASID table entry.
>
> int invalidate(struct device *, int pasid, void *ctx,
> unsigned long vaddr, size_t size)
> Invalidate TLB entries for this address range.
>
> int detach(struct device *, int pasid, void *ctx, bool detach_domain)
> Detach a context from the device, by clearing the PASID table entry
> and invalidating cached entries.
>
> void free(void *ctx)
> Free a context.
>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>

Hi Jean-Phillippe,

A few trivial comments from me in line. Otherwise this all seems sensible.

Jonathan

> ---
> drivers/iommu/Kconfig | 7 +
> drivers/iommu/Makefile | 1 +
> drivers/iommu/iommu-sva.c | 561 ++++++++++++++++++++++++++++++++++++++
> drivers/iommu/iommu-sva.h | 64 +++++
> drivers/iommu/iommu.c | 1 +
> include/linux/iommu.h | 3 +
> 6 files changed, 637 insertions(+)
> create mode 100644 drivers/iommu/iommu-sva.c
> create mode 100644 drivers/iommu/iommu-sva.h
>
> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> index d2fade984999..acca20e2da2f 100644
> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -102,6 +102,13 @@ config IOMMU_DMA
> select IRQ_MSI_IOMMU
> select NEED_SG_DMA_LENGTH
>
> +# Shared Virtual Addressing library
> +config IOMMU_SVA
> + bool
> + select IOASID
> + select IOMMU_API
> + select MMU_NOTIFIER
> +
> config FSL_PAMU
> bool "Freescale IOMMU support"
> depends on PCI
> diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
> index 9f33fdb3bb05..40c800dd4e3e 100644
> --- a/drivers/iommu/Makefile
> +++ b/drivers/iommu/Makefile
> @@ -37,3 +37,4 @@ obj-$(CONFIG_S390_IOMMU) += s390-iommu.o
> obj-$(CONFIG_QCOM_IOMMU) += qcom_iommu.o
> obj-$(CONFIG_HYPERV_IOMMU) += hyperv-iommu.o
> obj-$(CONFIG_VIRTIO_IOMMU) += virtio-iommu.o
> +obj-$(CONFIG_IOMMU_SVA) += iommu-sva.o
> diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
> new file mode 100644
> index 000000000000..64f1d1c82383
> --- /dev/null
> +++ b/drivers/iommu/iommu-sva.c
> @@ -0,0 +1,561 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Manage PASIDs and bind process address spaces to devices.
> + *
> + * Copyright (C) 2018 ARM Ltd.

Worth updating the date?

> + */
> +
> +#include <linux/idr.h>
> +#include <linux/ioasid.h>
> +#include <linux/iommu.h>
> +#include <linux/sched/mm.h>
> +#include <linux/slab.h>
> +#include <linux/spinlock.h>
> +
> +#include "iommu-sva.h"
> +
> +/**
> + * DOC: io_mm model
> + *
> + * The io_mm keeps track of process address spaces shared between CPU and IOMMU.
> + * The following example illustrates the relation between structures
> + * iommu_domain, io_mm and iommu_sva. The iommu_sva struct is a bond between
> + * io_mm and device. A device can have multiple io_mm and an io_mm may be bound
> + * to multiple devices.
> + * ___________________________
> + * | IOMMU domain A |
> + * | ________________ |
> + * | | IOMMU group | +------- io_pgtables
> + * | | | |
> + * | | dev 00:00.0 ----+------- bond 1 --- io_mm X
> + * | |________________| \ |
> + * | '----- bond 2 ---.
> + * |___________________________| \
> + * ___________________________ \
> + * | IOMMU domain B | io_mm Y
> + * | ________________ | / /
> + * | | IOMMU group | | / /
> + * | | | | / /
> + * | | dev 00:01.0 ------------ bond 3 -' /
> + * | | dev 00:01.1 ------------ bond 4 --'
> + * | |________________| |
> + * | +------- io_pgtables
> + * |___________________________|
> + *
> + * In this example, device 00:00.0 is in domain A, devices 00:01.* are in domain
> + * B. All devices within the same domain access the same address spaces. Device
> + * 00:00.0 accesses address spaces X and Y, each corresponding to an mm_struct.
> + * Devices 00:01.* only access address space Y. In addition each
> + * IOMMU_DOMAIN_DMA domain has a private address space, io_pgtable, that is
> + * managed with iommu_map()/iommu_unmap(), and isn't shared with the CPU MMU.
> + *
> + * To obtain the above configuration, users would for instance issue the
> + * following calls:
> + *
> + * iommu_sva_bind_device(dev 00:00.0, mm X, ...) -> bond 1
> + * iommu_sva_bind_device(dev 00:00.0, mm Y, ...) -> bond 2
> + * iommu_sva_bind_device(dev 00:01.0, mm Y, ...) -> bond 3
> + * iommu_sva_bind_device(dev 00:01.1, mm Y, ...) -> bond 4
> + *
> + * A single Process Address Space ID (PASID) is allocated for each mm. In the
> + * example, devices use PASID 1 to read/write into address space X and PASID 2
> + * to read/write into address space Y. Calling iommu_sva_get_pasid() on bond 1
> + * returns 1, and calling it on bonds 2-4 returns 2.
> + *
> + * Hardware tables describing this configuration in the IOMMU would typically
> + * look like this:
> + *
> + * PASID tables
> + * of domain A
> + * .->+--------+
> + * / 0 | |-------> io_pgtable
> + * / +--------+
> + * Device tables / 1 | |-------> pgd X
> + * +--------+ / +--------+
> + * 00:00.0 | A |-' 2 | |--.
> + * +--------+ +--------+ \
> + * : : 3 | | \
> + * +--------+ +--------+ --> pgd Y
> + * 00:01.0 | B |--. /
> + * +--------+ \ |
> + * 00:01.1 | B |----+ PASID tables |
> + * +--------+ \ of domain B |
> + * '->+--------+ |
> + * 0 | |-- | --> io_pgtable
> + * +--------+ |
> + * 1 | | |
> + * +--------+ |
> + * 2 | |---'
> + * +--------+
> + * 3 | |
> + * +--------+
> + *
> + * With this model, a single call binds all devices in a given domain to an
> + * address space. Other devices in the domain will get the same bond implicitly.
> + * However, users must issue one bind() for each device, because IOMMUs may
> + * implement SVA differently. Furthermore, mandating one bind() per device
> + * allows the driver to perform sanity-checks on device capabilities.

> + *
> + * In some IOMMUs, one entry of the PASID table (typically the first one) can
> + * hold non-PASID translations. In this case PASID 0 is reserved and the first
> + * entry points to the io_pgtable pointer. In other IOMMUs the io_pgtable
> + * pointer is held in the device table and PASID 0 is available to the
> + * allocator.

Is it worth hammering home in here that we can only do this because the PASID space
is global (with exception of PASID 0)? It's a convenient simplification but not
necessarily a hardware restriction so perhaps we should remind people somewhere in here?

> + */
> +
> +struct io_mm {
> + struct list_head devices;
> + struct mm_struct *mm;
> + struct mmu_notifier notifier;
> +
> + /* Late initialization */
> + const struct io_mm_ops *ops;
> + void *ctx;
> + int pasid;
> +};
> +
> +#define to_io_mm(mmu_notifier) container_of(mmu_notifier, struct io_mm, notifier)
> +#define to_iommu_bond(handle) container_of(handle, struct iommu_bond, sva)

Code ordering wise, do we want this after the definition of iommu_bond?

For both of these it's a bit non obvious what they come 'from'.
I wouldn't naturally assume to_io_mm gets me from notifier to the io_mm
for example. Not sure it matters though if these are only used in a few
places.

> +
> +struct iommu_bond {
> + struct iommu_sva sva;
> + struct io_mm __rcu *io_mm;
> +
> + struct list_head mm_head;
> + void *drvdata;
> + struct rcu_head rcu_head;
> + refcount_t refs;
> +};
> +
> +static DECLARE_IOASID_SET(shared_pasid);
> +
> +static struct mmu_notifier_ops iommu_mmu_notifier_ops;
> +
> +/*
> + * Serializes modifications of bonds.
> + * Lock order: Device SVA mutex; global SVA mutex; IOASID lock
> + */
> +static DEFINE_MUTEX(iommu_sva_lock);
> +
> +struct io_mm_alloc_params {
> + const struct io_mm_ops *ops;
> + int min_pasid, max_pasid;
> +};
> +
> +static struct mmu_notifier *io_mm_alloc(struct mm_struct *mm, void *privdata)
> +{
> + int ret;
> + struct io_mm *io_mm;
> + struct io_mm_alloc_params *params = privdata;
> +
> + io_mm = kzalloc(sizeof(*io_mm), GFP_KERNEL);
> + if (!io_mm)
> + return ERR_PTR(-ENOMEM);
> +
> + io_mm->mm = mm;
> + io_mm->ops = params->ops;
> + INIT_LIST_HEAD(&io_mm->devices);
> +
> + io_mm->pasid = ioasid_alloc(&shared_pasid, params->min_pasid,
> + params->max_pasid, io_mm->mm);
> + if (io_mm->pasid == INVALID_IOASID) {
> + ret = -ENOSPC;
> + goto err_free_io_mm;
> + }
> +
> + io_mm->ctx = params->ops->alloc(mm);
> + if (IS_ERR(io_mm->ctx)) {
> + ret = PTR_ERR(io_mm->ctx);
> + goto err_free_pasid;
> + }
> + return &io_mm->notifier;
> +
> +err_free_pasid:
> + ioasid_free(io_mm->pasid);
> +err_free_io_mm:
> + kfree(io_mm);
> + return ERR_PTR(ret);
> +}
> +
> +static void io_mm_free(struct mmu_notifier *mn)
> +{
> + struct io_mm *io_mm = to_io_mm(mn);
> +
> + WARN_ON(!list_empty(&io_mm->devices));
> +
> + io_mm->ops->release(io_mm->ctx);
> + ioasid_free(io_mm->pasid);
> + kfree(io_mm);
> +}
> +
> +/*
> + * io_mm_get - Allocate an io_mm or get the existing one for the given mm
> + * @mm: the mm
> + * @ops: callbacks for the IOMMU driver
> + * @min_pasid: minimum PASID value (inclusive)
> + * @max_pasid: maximum PASID value (inclusive)
> + *
> + * Returns a valid io_mm or an error pointer.
> + */
> +static struct io_mm *io_mm_get(struct mm_struct *mm,
> + const struct io_mm_ops *ops,
> + int min_pasid, int max_pasid)
> +{
> + struct io_mm *io_mm;
> + struct mmu_notifier *mn;
> + struct io_mm_alloc_params params = {
> + .ops = ops,
> + .min_pasid = min_pasid,
> + .max_pasid = max_pasid,
> + };
> +
> + /*
> + * A single notifier can exist for this (ops, mm) pair. Allocate it if
> + * necessary.
> + */
> + mn = mmu_notifier_get(&iommu_mmu_notifier_ops, mm, &params);
> + if (IS_ERR(mn))
> + return ERR_CAST(mn);
> + io_mm = to_io_mm(mn);
> +
> + if (WARN_ON(io_mm->ops != ops)) {
> + mmu_notifier_put(mn);
> + return ERR_PTR(-EINVAL);
> + }
> +
> + return io_mm;
> +}
> +
> +static void io_mm_put(struct io_mm *io_mm)
> +{
> + mmu_notifier_put(&io_mm->notifier);
> +}
> +
> +static struct iommu_sva *
> +io_mm_attach(struct device *dev, struct io_mm *io_mm, void *drvdata)
> +{
> + int ret = 0;

I'm fairly sure this is set in all paths below. Now, of course the
compiler might not think that in which case fair enough :)

> + bool attach_domain = true;
> + struct iommu_bond *bond, *tmp;
> + struct iommu_domain *domain, *other;
> + struct iommu_sva_param *param = dev->iommu_param->sva_param;
> +
> + domain = iommu_get_domain_for_dev(dev);
> +
> + bond = kzalloc(sizeof(*bond), GFP_KERNEL);
> + if (!bond)
> + return ERR_PTR(-ENOMEM);
> +
> + bond->sva.dev = dev;
> + bond->drvdata = drvdata;
> + refcount_set(&bond->refs, 1);
> + RCU_INIT_POINTER(bond->io_mm, io_mm);
> +
> + mutex_lock(&iommu_sva_lock);
> + /* Is it already bound to the device or domain? */
> + list_for_each_entry(tmp, &io_mm->devices, mm_head) {
> + if (tmp->sva.dev != dev) {
> + other = iommu_get_domain_for_dev(tmp->sva.dev);
> + if (domain == other)
> + attach_domain = false;
> +
> + continue;
> + }
> +
> + if (WARN_ON(tmp->drvdata != drvdata)) {
> + ret = -EINVAL;
> + goto err_free;
> + }
> +
> + /*
> + * Hold a single io_mm reference per bond. Note that we can't
> + * return an error after this, otherwise the caller would drop
> + * an additional reference to the io_mm.
> + */
> + refcount_inc(&tmp->refs);
> + io_mm_put(io_mm);
> + kfree(bond);

Free outside the lock would be ever so slightly more logical given we allocated
before taking the lock.

> + mutex_unlock(&iommu_sva_lock);
> + return &tmp->sva;
> + }
> +
> + list_add_rcu(&bond->mm_head, &io_mm->devices);
> + param->nr_bonds++;
> + mutex_unlock(&iommu_sva_lock);
> +
> + ret = io_mm->ops->attach(bond->sva.dev, io_mm->pasid, io_mm->ctx,
> + attach_domain);
> + if (ret)
> + goto err_remove;
> +
> + return &bond->sva;
> +
> +err_remove:
> + /*
> + * At this point concurrent threads may have started to access the
> + * io_mm->devices list in order to invalidate address ranges, which
> + * requires to free the bond via kfree_rcu()
> + */
> + mutex_lock(&iommu_sva_lock);
> + param->nr_bonds--;
> + list_del_rcu(&bond->mm_head);
> +
> +err_free:
> + mutex_unlock(&iommu_sva_lock);
> + kfree_rcu(bond, rcu_head);

I don't suppose it matters really but we don't need the rcu free if
we follow the err_free goto. Perhaps we are cleaner in this case
to not use a unified exit path but do that case inline?

> + return ERR_PTR(ret);
> +}
> +
> +static void io_mm_detach_locked(struct iommu_bond *bond)
> +{
> + struct io_mm *io_mm;
> + struct iommu_bond *tmp;
> + bool detach_domain = true;
> + struct iommu_domain *domain, *other;
> +
> + io_mm = rcu_dereference_protected(bond->io_mm,
> + lockdep_is_held(&iommu_sva_lock));
> + if (!io_mm)
> + return;
> +
> + domain = iommu_get_domain_for_dev(bond->sva.dev);
> +
> + /* Are other devices in the same domain still attached to this mm? */
> + list_for_each_entry(tmp, &io_mm->devices, mm_head) {
> + if (tmp == bond)
> + continue;
> + other = iommu_get_domain_for_dev(tmp->sva.dev);
> + if (domain == other) {
> + detach_domain = false;
> + break;
> + }
> + }
> +
> + io_mm->ops->detach(bond->sva.dev, io_mm->pasid, io_mm->ctx,
> + detach_domain);
> +
> + list_del_rcu(&bond->mm_head);
> + RCU_INIT_POINTER(bond->io_mm, NULL);
> +
> + /* Free after RCU grace period */
> + io_mm_put(io_mm);
> +}
> +
> +/*
> + * io_mm_release - release MMU notifier
> + *
> + * Called when the mm exits. Some devices may still be bound to the io_mm. A few
> + * things need to be done before it is safe to release:
> + *
> + * - Tell the device driver to stop using this PASID.
> + * - Clear the PASID table and invalidate TLBs.
> + * - Drop all references to this io_mm.
> + */
> +static void io_mm_release(struct mmu_notifier *mn, struct mm_struct *mm)
> +{
> + struct iommu_bond *bond, *next;
> + struct io_mm *io_mm = to_io_mm(mn);
> +
> + mutex_lock(&iommu_sva_lock);
> + list_for_each_entry_safe(bond, next, &io_mm->devices, mm_head) {
> + struct device *dev = bond->sva.dev;
> + struct iommu_sva *sva = &bond->sva;
> +
> + if (sva->ops && sva->ops->mm_exit &&
> + sva->ops->mm_exit(dev, sva, bond->drvdata))
> + dev_WARN(dev, "possible leak of PASID %u",
> + io_mm->pasid);
> +
> + /* unbind() frees the bond, we just detach it */
> + io_mm_detach_locked(bond);
> + }
> + mutex_unlock(&iommu_sva_lock);
> +}
> +
> +static void io_mm_invalidate_range(struct mmu_notifier *mn,
> + struct mm_struct *mm, unsigned long start,
> + unsigned long end)
> +{
> + struct iommu_bond *bond;
> + struct io_mm *io_mm = to_io_mm(mn);
> +
> + rcu_read_lock();
> + list_for_each_entry_rcu(bond, &io_mm->devices, mm_head)
> + io_mm->ops->invalidate(bond->sva.dev, io_mm->pasid, io_mm->ctx,
> + start, end - start);
> + rcu_read_unlock();
> +}
> +
> +static struct mmu_notifier_ops iommu_mmu_notifier_ops = {
> + .alloc_notifier = io_mm_alloc,
> + .free_notifier = io_mm_free,
> + .release = io_mm_release,
> + .invalidate_range = io_mm_invalidate_range,
> +};
> +
> +struct iommu_sva *
> +iommu_sva_bind_generic(struct device *dev, struct mm_struct *mm,
> + const struct io_mm_ops *ops, void *drvdata)
> +{
> + struct io_mm *io_mm;
> + struct iommu_sva *handle;
> + struct iommu_param *param = dev->iommu_param;
> +
> + if (!param)
> + return ERR_PTR(-ENODEV);
> +
> + mutex_lock(&param->sva_lock);
> + if (!param->sva_param) {
> + handle = ERR_PTR(-ENODEV);
> + goto out_unlock;
> + }
> +
> + io_mm = io_mm_get(mm, ops, param->sva_param->min_pasid,
> + param->sva_param->max_pasid);
> + if (IS_ERR(io_mm)) {
> + handle = ERR_CAST(io_mm);
> + goto out_unlock;
> + }
> +
> + handle = io_mm_attach(dev, io_mm, drvdata);
> + if (IS_ERR(handle))
> + io_mm_put(io_mm);
> +
> +out_unlock:
> + mutex_unlock(&param->sva_lock);
> + return handle;
> +}
> +EXPORT_SYMBOL_GPL(iommu_sva_bind_generic);
> +
> +static void iommu_sva_unbind_locked(struct iommu_bond *bond)
> +{
> + struct device *dev = bond->sva.dev;
> + struct iommu_sva_param *param = dev->iommu_param->sva_param;
> +
> + if (!refcount_dec_and_test(&bond->refs))
> + return;
> +
> + io_mm_detach_locked(bond);
> + param->nr_bonds--;
> + kfree_rcu(bond, rcu_head);
> +}
> +
> +void iommu_sva_unbind_generic(struct iommu_sva *handle)
> +{
> + struct iommu_param *param = handle->dev->iommu_param;
> +
> + if (WARN_ON(!param))
> + return;
> +
> + mutex_lock(&param->sva_lock);
> + mutex_lock(&iommu_sva_lock);
> + iommu_sva_unbind_locked(to_iommu_bond(handle));
> + mutex_unlock(&iommu_sva_lock);
> + mutex_unlock(&param->sva_lock);
> +}
> +EXPORT_SYMBOL_GPL(iommu_sva_unbind_generic);
> +
> +/**
> + * iommu_sva_enable() - Enable Shared Virtual Addressing for a device
> + * @dev: the device
> + * @sva_param: the parameters.
> + *
> + * Called by an IOMMU driver to setup the SVA parameters
> + * @sva_param is duplicated and can be freed when this function returns.
> + *
> + * Return 0 if initialization succeeded, or an error.
> + */
> +int iommu_sva_enable(struct device *dev, struct iommu_sva_param *sva_param)
> +{
> + int ret;
> + struct iommu_sva_param *new_param;
> + struct iommu_param *param = dev->iommu_param;
> +
> + if (!param)
> + return -ENODEV;
> +
> + new_param = kmemdup(sva_param, sizeof(*new_param), GFP_KERNEL);
> + if (!new_param)
> + return -ENOMEM;
> +
> + mutex_lock(&param->sva_lock);
> + if (param->sva_param) {
> + ret = -EEXIST;
> + goto err_unlock;
> + }
> +
> + dev->iommu_param->sva_param = new_param;
> + mutex_unlock(&param->sva_lock);
> + return 0;
> +
> +err_unlock:
> + mutex_unlock(&param->sva_lock);
> + kfree(new_param);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(iommu_sva_enable);
> +
> +/**
> + * iommu_sva_disable() - Disable Shared Virtual Addressing for a device
> + * @dev: the device
> + *
> + * IOMMU drivers call this to disable SVA.
> + */
> +int iommu_sva_disable(struct device *dev)
> +{
> + int ret = 0;
> + struct iommu_param *param = dev->iommu_param;
> +
> + if (!param)
> + return -EINVAL;
> +
> + mutex_lock(&param->sva_lock);
> + if (!param->sva_param) {
> + ret = -ENODEV;
> + goto out_unlock;
> + }
> +
> + /* Require that all contexts are unbound */
> + if (param->sva_param->nr_bonds) {
> + ret = -EBUSY;
> + goto out_unlock;
> + }
> +
> + kfree(param->sva_param);
> + param->sva_param = NULL;
> +out_unlock:
> + mutex_unlock(&param->sva_lock);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(iommu_sva_disable);
> +
> +bool iommu_sva_enabled(struct device *dev)
> +{
> + bool enabled;
> + struct iommu_param *param = dev->iommu_param;
> +
> + if (!param)
> + return false;
> +
> + mutex_lock(&param->sva_lock);
> + enabled = !!param->sva_param;
> + mutex_unlock(&param->sva_lock);
> + return enabled;
> +}
> +EXPORT_SYMBOL_GPL(iommu_sva_enabled);
> +
> +int iommu_sva_get_pasid_generic(struct iommu_sva *handle)
> +{
> + struct io_mm *io_mm;
> + int pasid = IOMMU_PASID_INVALID;
> + struct iommu_bond *bond = to_iommu_bond(handle);
> +
> + rcu_read_lock();
> + io_mm = rcu_dereference(bond->io_mm);
> + if (io_mm)
> + pasid = io_mm->pasid;
> + rcu_read_unlock();
> + return pasid;
> +}
> +EXPORT_SYMBOL_GPL(iommu_sva_get_pasid_generic);
> diff --git a/drivers/iommu/iommu-sva.h b/drivers/iommu/iommu-sva.h
> new file mode 100644
> index 000000000000..dd55c2db0936
> --- /dev/null
> +++ b/drivers/iommu/iommu-sva.h
> @@ -0,0 +1,64 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * SVA library for IOMMU drivers
> + */
> +#ifndef _IOMMU_SVA_H
> +#define _IOMMU_SVA_H
> +
> +#include <linux/iommu.h>
> +#include <linux/kref.h>
> +#include <linux/mmu_notifier.h>
> +
> +struct io_mm_ops {
> + /* Allocate a PASID context for an mm */
> + void *(*alloc)(struct mm_struct *mm);
> +
> + /*
> + * Attach a PASID context to a device. Write the entry into the PASID
> + * table.
> + *
> + * @attach_domain is true when no other device in the IOMMU domain is
> + * already attached to this context. IOMMU drivers that share the
> + * PASID tables within a domain don't need to write the PASID entry
> + * when @attach_domain is false.
> + */
> + int (*attach)(struct device *dev, int pasid, void *ctx,
> + bool attach_domain);
> +
> + /*
> + * Detach a PASID context from a device. Clear the entry from the PASID
> + * table and invalidate if necessary.
> + *
> + * @detach_domain is true when no other device in the IOMMU domain is
> + * still attached to this context. IOMMU drivers that share the PASID
> + * table within a domain don't need to clear the PASID entry when
> + * @detach_domain is false, only invalidate the caches.
> + */
> + void (*detach)(struct device *dev, int pasid, void *ctx,
> + bool detach_domain);
> +
> + /* Invalidate a range of addresses. Cannot sleep. */
> + void (*invalidate)(struct device *dev, int pasid, void *ctx,
> + unsigned long vaddr, size_t size);
> +
> + /* Free a context. Cannot sleep. */
> + void (*release)(void *ctx);
> +};
> +
> +struct iommu_sva_param {
> + u32 min_pasid;
> + u32 max_pasid;
> + int nr_bonds;
> +};
> +
> +struct iommu_sva *
> +iommu_sva_bind_generic(struct device *dev, struct mm_struct *mm,
> + const struct io_mm_ops *ops, void *drvdata);
> +void iommu_sva_unbind_generic(struct iommu_sva *handle);
> +int iommu_sva_get_pasid_generic(struct iommu_sva *handle);
> +
> +int iommu_sva_enable(struct device *dev, struct iommu_sva_param *sva_param);
> +int iommu_sva_disable(struct device *dev);
> +bool iommu_sva_enabled(struct device *dev);
> +
> +#endif /* _IOMMU_SVA_H */
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 3e3528436e0b..c8bd972c1788 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -164,6 +164,7 @@ static struct iommu_param *iommu_get_dev_param(struct device *dev)
> return NULL;
>
> mutex_init(&param->lock);
> + mutex_init(&param->sva_lock);
> dev->iommu_param = param;
> return param;
> }
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 1739f8a7a4b4..83397ae88d2d 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -368,6 +368,7 @@ struct iommu_fault_param {
> * struct iommu_param - collection of per-device IOMMU data
> *
> * @fault_param: IOMMU detected device fault reporting data
> + * @sva_param: IOMMU parameter for SVA
> *
> * TODO: migrate other per device data pointers under iommu_dev_data, e.g.
> * struct iommu_group *iommu_group;
> @@ -376,6 +377,8 @@ struct iommu_fault_param {
> struct iommu_param {
> struct mutex lock;
> struct iommu_fault_param *fault_param;
> + struct mutex sva_lock;
> + struct iommu_sva_param *sva_param;
> };
>
> int iommu_device_register(struct iommu_device *iommu);