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iommu: Introduce a replace API for device pasid

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Provide a high-level API to allow replacements of one domain with another
for specific pasid of a device. This is similar to
iommu_replace_group_handle() and it is expected to be used only by IOMMUFD.

Link: https://patch.msgid.link/r/20250321171940.7213-3-yi.l.liu@intel.com
Co-developed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
This commit is contained in:
Yi Liu 2025-03-21 10:19:24 -07:00 committed by Jason Gunthorpe
parent ada14b9f1a
commit 8a9e1e773f
2 changed files with 114 additions and 4 deletions
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3
drivers/iommu/iommu-priv.h
View File

@ -56,4 +56,7 @@ static inline int iommufd_sw_msi(struct iommu_domain *domain,
}
#endif /* CONFIG_IOMMUFD_DRIVER_CORE && CONFIG_IRQ_MSI_IOMMU */
int iommu_replace_device_pasid(struct iommu_domain *domain,
struct device *dev, ioasid_t pasid,
struct iommu_attach_handle *handle);
#endif /* __LINUX_IOMMU_PRIV_H */

115
drivers/iommu/iommu.c
View File

@ -514,6 +514,13 @@ static void iommu_deinit_device(struct device *dev)
dev_iommu_free(dev);
}
static struct iommu_domain *pasid_array_entry_to_domain(void *entry)
{
if (xa_pointer_tag(entry) == IOMMU_PASID_ARRAY_DOMAIN)
return xa_untag_pointer(entry);
return ((struct iommu_attach_handle *)xa_untag_pointer(entry))->domain;
}
DEFINE_MUTEX(iommu_probe_device_lock);
static int __iommu_probe_device(struct device *dev, struct list_head *group_list)
@ -3324,14 +3331,15 @@ static void iommu_remove_dev_pasid(struct device *dev, ioasid_t pasid,
}
static int __iommu_set_group_pasid(struct iommu_domain *domain,
struct iommu_group *group, ioasid_t pasid)
struct iommu_group *group, ioasid_t pasid,
struct iommu_domain *old)
{
struct group_device *device, *last_gdev;
int ret;
for_each_group_device(group, device) {
ret = domain->ops->set_dev_pasid(domain, device->dev,
pasid, NULL);
pasid, old);
if (ret)
goto err_revert;
}
@ -3343,7 +3351,15 @@ static int __iommu_set_group_pasid(struct iommu_domain *domain,
for_each_group_device(group, device) {
if (device == last_gdev)
break;
iommu_remove_dev_pasid(device->dev, pasid, domain);
/*
* If no old domain, undo the succeeded devices/pasid.
* Otherwise, rollback the succeeded devices/pasid to the old
* domain. And it is a driver bug to fail attaching with a
* previously good domain.
*/
if (!old || WARN_ON(old->ops->set_dev_pasid(old, device->dev,
pasid, domain)))
iommu_remove_dev_pasid(device->dev, pasid, domain);
}
return ret;
}
@ -3412,7 +3428,7 @@ int iommu_attach_device_pasid(struct iommu_domain *domain,
if (ret)
goto out_unlock;
ret = __iommu_set_group_pasid(domain, group, pasid);
ret = __iommu_set_group_pasid(domain, group, pasid, NULL);
if (ret) {
xa_release(&group->pasid_array, pasid);
goto out_unlock;
@ -3433,6 +3449,97 @@ int iommu_attach_device_pasid(struct iommu_domain *domain,
}
EXPORT_SYMBOL_GPL(iommu_attach_device_pasid);
/**
* iommu_replace_device_pasid - Replace the domain that a specific pasid
* of the device is attached to
* @domain: the new iommu domain
* @dev: the attached device.
* @pasid: the pasid of the device.
* @handle: the attach handle.
*
* This API allows the pasid to switch domains. The @pasid should have been
* attached. Otherwise, this fails. The pasid will keep the old configuration
* if replacement failed.
*
* Caller should always provide a new handle to avoid race with the paths
* that have lockless reference to handle if it intends to pass a valid handle.
*
* Return 0 on success, or an error.
*/
int iommu_replace_device_pasid(struct iommu_domain *domain,
struct device *dev, ioasid_t pasid,
struct iommu_attach_handle *handle)
{
/* Caller must be a probed driver on dev */
struct iommu_group *group = dev->iommu_group;
struct iommu_attach_handle *entry;
struct iommu_domain *curr_domain;
void *curr;
int ret;
if (!group)
return -ENODEV;
if (!domain->ops->set_dev_pasid)
return -EOPNOTSUPP;
if (dev_iommu_ops(dev) != domain->owner ||
pasid == IOMMU_NO_PASID || !handle)
return -EINVAL;
mutex_lock(&group->mutex);
entry = iommu_make_pasid_array_entry(domain, handle);
curr = xa_cmpxchg(&group->pasid_array, pasid, NULL,
XA_ZERO_ENTRY, GFP_KERNEL);
if (xa_is_err(curr)) {
ret = xa_err(curr);
goto out_unlock;
}
/*
* No domain (with or without handle) attached, hence not
* a replace case.
*/
if (!curr) {
xa_release(&group->pasid_array, pasid);
ret = -EINVAL;
goto out_unlock;
}
/*
* Reusing handle is problematic as there are paths that refers
* the handle without lock. To avoid race, reject the callers that
* attempt it.
*/
if (curr == entry) {
WARN_ON(1);
ret = -EINVAL;
goto out_unlock;
}
curr_domain = pasid_array_entry_to_domain(curr);
ret = 0;
if (curr_domain != domain) {
ret = __iommu_set_group_pasid(domain, group,
pasid, curr_domain);
if (ret)
goto out_unlock;
}
/*
* The above xa_cmpxchg() reserved the memory, and the
* group->mutex is held, this cannot fail.
*/
WARN_ON(xa_is_err(xa_store(&group->pasid_array,
pasid, entry, GFP_KERNEL)));
out_unlock:
mutex_unlock(&group->mutex);
return ret;
}
EXPORT_SYMBOL_NS_GPL(iommu_replace_device_pasid, "IOMMUFD_INTERNAL");
/*
* iommu_detach_device_pasid() - Detach the domain from pasid of device
* @domain: the iommu domain.