| Message ID | 20230926092651.17041-2-yi.l.liu@intel.com |
|---|---|
| State | New |
| Headers | show |
| Series | iommufd support pasid attach/replace | expand |
On 9/26/23 5:26 PM, Yi Liu wrote: > From: Lu Baolu <baolu.lu@linux.intel.com> > > Provide a high-level API to allow replacements of one domain with > another for specific pasid of a device. This is similar to > iommu_group_replace_domain() and it is also expected to be used > only by IOMMUFD. > > Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> > Signed-off-by: Yi Liu <yi.l.liu@intel.com> > --- > drivers/iommu/iommu-priv.h | 2 ++ > drivers/iommu/iommu.c | 73 ++++++++++++++++++++++++++++++-------- > 2 files changed, 60 insertions(+), 15 deletions(-) > [...] > @@ -3433,8 +3443,8 @@ EXPORT_SYMBOL_GPL(iommu_attach_device_pasid); > * The @domain must have been attached to @pasid of the @dev with > * iommu_attach_device_pasid(). > */ > -void iommu_detach_device_pasid(struct iommu_domain *domain, struct device *dev, > - ioasid_t pasid) > +void iommu_detach_device_pasid(struct iommu_domain *domain, > + struct device *dev, ioasid_t pasid) Above change is irrelevant. > { > struct iommu_group *group = iommu_group_get(dev); > > @@ -3447,6 +3457,39 @@ void iommu_detach_device_pasid(struct iommu_domain *domain, struct device *dev, > } > EXPORT_SYMBOL_GPL(iommu_detach_device_pasid); > > +/** > + * iommu_replace_device_pasid - replace the domain that a pasid is attached to > + * @domain: new IOMMU domain to replace with > + * @dev: the physical device > + * @pasid: pasid that will be attached to the new domain > + * > + * This API allows the pasid to switch domains. Return 0 on success, or an > + * error. The pasid will roll back to use the old domain if failure. The > + * caller could call iommu_detach_device_pasid() before free the old domain > + * in order to avoid use-after-free case. The comment does not match the actual behavior of the code. We need to discuss and agree on which state the PASID should park in if replacing the domain fails. > + */ > +int iommu_replace_device_pasid(struct iommu_domain *domain, > + struct device *dev, ioasid_t pasid) > +{ > + struct iommu_group *group = dev->iommu_group; > + int ret; > + > + if (!domain) > + return -EINVAL; > + > + if (!group) > + return -ENODEV; > + > + mutex_lock(&group->mutex); > + __iommu_remove_group_pasid(group, pasid); > + xa_erase(&group->pasid_array, pasid); > + ret = __iommu_group_attach_pasid(domain, group, pasid); > + mutex_unlock(&group->mutex); > + > + return ret; > +} > +EXPORT_SYMBOL_NS_GPL(iommu_replace_device_pasid, IOMMUFD_INTERNAL); > + > /* > * iommu_get_domain_for_dev_pasid() - Retrieve domain for @pasid of @dev > * @dev: the queried device Best regards, baolu
> From: Baolu Lu <baolu.lu@linux.intel.com> > Sent: Wednesday, September 27, 2023 10:05 AM > > On 9/26/23 5:26 PM, Yi Liu wrote: > > > > +/** > > + * iommu_replace_device_pasid - replace the domain that a pasid is > attached to > > + * @domain: new IOMMU domain to replace with > > + * @dev: the physical device > > + * @pasid: pasid that will be attached to the new domain > > + * > > + * This API allows the pasid to switch domains. Return 0 on success, or an > > + * error. The pasid will roll back to use the old domain if failure. The > > + * caller could call iommu_detach_device_pasid() before free the old > domain > > + * in order to avoid use-after-free case. > > The comment does not match the actual behavior of the code. We need to > discuss and agree on which state the PASID should park in if replacing > the domain fails. > there is no legacy as in group_set_domain and iommufd is the only caller of this new function. So IMHO the description above is the right thing to do and the code should be updated to match it.
diff --git a/drivers/iommu/iommu-priv.h b/drivers/iommu/iommu-priv.h index 2024a2313348..5c32637f6325 100644 --- a/drivers/iommu/iommu-priv.h +++ b/drivers/iommu/iommu-priv.h @@ -19,6 +19,8 @@ static inline const struct iommu_ops *dev_iommu_ops(struct device *dev) int iommu_group_replace_domain(struct iommu_group *group, struct iommu_domain *new_domain); +int iommu_replace_device_pasid(struct iommu_domain *domain, + struct device *dev, ioasid_t pasid); int iommu_device_register_bus(struct iommu_device *iommu, const struct iommu_ops *ops, struct bus_type *bus, diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index e53c9e659ae6..b47581c7b1c6 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -3382,6 +3382,27 @@ static void __iommu_remove_group_pasid(struct iommu_group *group, } } +static int __iommu_group_attach_pasid(struct iommu_domain *domain, + struct iommu_group *group, ioasid_t pasid) +{ + void *curr; + int ret; + + lockdep_assert_held(&group->mutex); + + curr = xa_cmpxchg(&group->pasid_array, pasid, NULL, domain, GFP_KERNEL); + if (curr) + return xa_err(curr) ? : -EBUSY; + + ret = __iommu_set_group_pasid(domain, group, pasid); + if (ret) { + __iommu_remove_group_pasid(group, pasid); + xa_erase(&group->pasid_array, pasid); + } + + return ret; +} + /* * iommu_attach_device_pasid() - Attach a domain to pasid of device * @domain: the iommu domain. @@ -3394,7 +3415,6 @@ int iommu_attach_device_pasid(struct iommu_domain *domain, struct device *dev, ioasid_t pasid) { struct iommu_group *group; - void *curr; int ret; if (!domain->ops->set_dev_pasid) @@ -3405,19 +3425,9 @@ int iommu_attach_device_pasid(struct iommu_domain *domain, return -ENODEV; mutex_lock(&group->mutex); - curr = xa_cmpxchg(&group->pasid_array, pasid, NULL, domain, GFP_KERNEL); - if (curr) { - ret = xa_err(curr) ? : -EBUSY; - goto out_unlock; - } - - ret = __iommu_set_group_pasid(domain, group, pasid); - if (ret) { - __iommu_remove_group_pasid(group, pasid); - xa_erase(&group->pasid_array, pasid); - } -out_unlock: + ret = __iommu_group_attach_pasid(domain, group, pasid); mutex_unlock(&group->mutex); + iommu_group_put(group); return ret; @@ -3433,8 +3443,8 @@ EXPORT_SYMBOL_GPL(iommu_attach_device_pasid); * The @domain must have been attached to @pasid of the @dev with * iommu_attach_device_pasid(). */ -void iommu_detach_device_pasid(struct iommu_domain *domain, struct device *dev, - ioasid_t pasid) +void iommu_detach_device_pasid(struct iommu_domain *domain, + struct device *dev, ioasid_t pasid) { struct iommu_group *group = iommu_group_get(dev); @@ -3447,6 +3457,39 @@ void iommu_detach_device_pasid(struct iommu_domain *domain, struct device *dev, } EXPORT_SYMBOL_GPL(iommu_detach_device_pasid); +/** + * iommu_replace_device_pasid - replace the domain that a pasid is attached to + * @domain: new IOMMU domain to replace with + * @dev: the physical device + * @pasid: pasid that will be attached to the new domain + * + * This API allows the pasid to switch domains. Return 0 on success, or an + * error. The pasid will roll back to use the old domain if failure. The + * caller could call iommu_detach_device_pasid() before free the old domain + * in order to avoid use-after-free case. + */ +int iommu_replace_device_pasid(struct iommu_domain *domain, + struct device *dev, ioasid_t pasid) +{ + struct iommu_group *group = dev->iommu_group; + int ret; + + if (!domain) + return -EINVAL; + + if (!group) + return -ENODEV; + + mutex_lock(&group->mutex); + __iommu_remove_group_pasid(group, pasid); + xa_erase(&group->pasid_array, pasid); + ret = __iommu_group_attach_pasid(domain, group, pasid); + mutex_unlock(&group->mutex); + + return ret; +} +EXPORT_SYMBOL_NS_GPL(iommu_replace_device_pasid, IOMMUFD_INTERNAL); + /* * iommu_get_domain_for_dev_pasid() - Retrieve domain for @pasid of @dev * @dev: the queried device