Messages in this thread | | | Date | Sun, 31 Jul 2022 20:55:04 +0800 | Subject | Re: [PATCH v10 08/12] iommu/sva: Refactoring iommu_sva_bind/unbind_device() | From | Yi Liu <> |
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On 2022/7/5 13:07, Lu Baolu wrote: > The existing iommu SVA interfaces are implemented by calling the SVA > specific iommu ops provided by the IOMMU drivers. There's no need for > any SVA specific ops in iommu_ops vector anymore as we can achieve > this through the generic attach/detach_dev_pasid domain ops. > > This refactors the IOMMU SVA interfaces implementation by using the > set/block_pasid_dev ops and align them with the concept of the SVA > iommu domain. Put the new SVA code in the sva related file in order > to make it self-contained. > > Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> > Tested-by: Zhangfei Gao <zhangfei.gao@linaro.org> > Tested-by: Tony Zhu <tony.zhu@intel.com> > --- > include/linux/iommu.h | 67 +++++++++++-------- > drivers/iommu/iommu-sva-lib.c | 98 ++++++++++++++++++++++++++++ > drivers/iommu/iommu.c | 119 ++++++++-------------------------- > 3 files changed, 165 insertions(+), 119 deletions(-) > > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index 42f0418dc22c..f59b0ecd3995 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -39,7 +39,6 @@ struct device; > struct iommu_domain; > struct iommu_domain_ops; > struct notifier_block; > -struct iommu_sva; > struct iommu_fault_event; > struct iommu_dma_cookie; > > @@ -57,6 +56,14 @@ struct iommu_domain_geometry { > bool force_aperture; /* DMA only allowed in mappable range? */ > }; > > +/** > + * struct iommu_sva - handle to a device-mm bond > + */ > +struct iommu_sva { > + struct device *dev; > + refcount_t users; > +}; > + > /* Domain feature flags */ > #define __IOMMU_DOMAIN_PAGING (1U << 0) /* Support for iommu_map/unmap */ > #define __IOMMU_DOMAIN_DMA_API (1U << 1) /* Domain for use in DMA-API > @@ -105,6 +112,7 @@ struct iommu_domain { > }; > struct { /* IOMMU_DOMAIN_SVA */ > struct mm_struct *mm; > + struct iommu_sva bond; > }; > }; > }; > @@ -638,13 +646,6 @@ struct iommu_fwspec { > /* ATS is supported */ > #define IOMMU_FWSPEC_PCI_RC_ATS (1 << 0) > > -/** > - * struct iommu_sva - handle to a device-mm bond > - */ > -struct iommu_sva { > - struct device *dev; > -}; > - > int iommu_fwspec_init(struct device *dev, struct fwnode_handle *iommu_fwnode, > const struct iommu_ops *ops); > void iommu_fwspec_free(struct device *dev); > @@ -685,11 +686,6 @@ int iommu_dev_enable_feature(struct device *dev, enum iommu_dev_features f); > int iommu_dev_disable_feature(struct device *dev, enum iommu_dev_features f); > bool iommu_dev_feature_enabled(struct device *dev, enum iommu_dev_features f); > > -struct iommu_sva *iommu_sva_bind_device(struct device *dev, > - struct mm_struct *mm); > -void iommu_sva_unbind_device(struct iommu_sva *handle); > -u32 iommu_sva_get_pasid(struct iommu_sva *handle); > - > int iommu_device_use_default_domain(struct device *dev); > void iommu_device_unuse_default_domain(struct device *dev); > > @@ -703,6 +699,8 @@ int iommu_attach_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_domain * > +iommu_get_domain_for_dev_pasid(struct device *dev, ioasid_t pasid); > #else /* CONFIG_IOMMU_API */ > > struct iommu_ops {}; > @@ -1033,21 +1031,6 @@ iommu_dev_disable_feature(struct device *dev, enum iommu_dev_features feat) > return -ENODEV; > } > > -static inline struct iommu_sva * > -iommu_sva_bind_device(struct device *dev, struct mm_struct *mm) > -{ > - return NULL; > -} > - > -static inline void iommu_sva_unbind_device(struct iommu_sva *handle) > -{ > -} > - > -static inline u32 iommu_sva_get_pasid(struct iommu_sva *handle) > -{ > - return IOMMU_PASID_INVALID; > -} > - > static inline struct iommu_fwspec *dev_iommu_fwspec_get(struct device *dev) > { > return NULL; > @@ -1093,6 +1076,12 @@ static inline void iommu_detach_device_pasid(struct iommu_domain *domain, > struct device *dev, ioasid_t pasid) > { > } > + > +static inline struct iommu_domain * > +iommu_get_domain_for_dev_pasid(struct device *dev, ioasid_t pasid) > +{ > + return NULL; > +} > #endif /* CONFIG_IOMMU_API */ > > /** > @@ -1118,4 +1107,26 @@ void iommu_debugfs_setup(void); > static inline void iommu_debugfs_setup(void) {} > #endif > > +#ifdef CONFIG_IOMMU_SVA > +struct iommu_sva *iommu_sva_bind_device(struct device *dev, > + struct mm_struct *mm); > +void iommu_sva_unbind_device(struct iommu_sva *handle); > +u32 iommu_sva_get_pasid(struct iommu_sva *handle); > +#else > +static inline struct iommu_sva * > +iommu_sva_bind_device(struct device *dev, struct mm_struct *mm) > +{ > + return NULL; > +} > + > +static inline void iommu_sva_unbind_device(struct iommu_sva *handle) > +{ > +} > + > +static inline u32 iommu_sva_get_pasid(struct iommu_sva *handle) > +{ > + return IOMMU_PASID_INVALID; > +} > +#endif /* CONFIG_IOMMU_SVA */ > + > #endif /* __LINUX_IOMMU_H */ > diff --git a/drivers/iommu/iommu-sva-lib.c b/drivers/iommu/iommu-sva-lib.c > index 106506143896..751366980232 100644 > --- a/drivers/iommu/iommu-sva-lib.c > +++ b/drivers/iommu/iommu-sva-lib.c > @@ -4,6 +4,7 @@ > */ > #include <linux/mutex.h> > #include <linux/sched/mm.h> > +#include <linux/iommu.h> > > #include "iommu-sva-lib.h" > > @@ -69,3 +70,100 @@ struct mm_struct *iommu_sva_find(ioasid_t pasid) > return ioasid_find(&iommu_sva_pasid, pasid, __mmget_not_zero); > } > EXPORT_SYMBOL_GPL(iommu_sva_find); > + > +/** > + * iommu_sva_bind_device() - Bind a process address space to a device > + * @dev: the device > + * @mm: the mm to bind, caller must hold a reference to mm_users > + * > + * Create a bond between device and address space, allowing the device to access > + * the mm using the returned PASID. If a bond already exists between @device and > + * @mm, it is returned and an additional reference is taken. Caller must call > + * iommu_sva_unbind_device() to release each reference. > + * > + * iommu_dev_enable_feature(dev, IOMMU_DEV_FEAT_SVA) must be called first, to > + * initialize the required SVA features. > + * > + * On error, returns an ERR_PTR value. > + */ > +struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm) > +{ > + struct iommu_domain *domain; > + ioasid_t max_pasids; > + int ret = -EINVAL; > + > + max_pasids = dev->iommu->max_pasids; > + if (!max_pasids) > + return ERR_PTR(-EOPNOTSUPP); > + > + /* Allocate mm->pasid if necessary. */ > + ret = iommu_sva_alloc_pasid(mm, 1, max_pasids - 1);
do we want to call mmgrab() before iomu_sva_alloc_pasid() to avoid using mm without any reference? In your current code, mmgrab() is called in iommu_sva_domain_alloc().
> + if (ret) > + return ERR_PTR(ret); > + > + mutex_lock(&iommu_sva_lock); > + /* Search for an existing domain. */ > + domain = iommu_get_domain_for_dev_pasid(dev, mm->pasid); > + if (domain) { > + refcount_inc(&domain->bond.users); > + goto out_success; > + } > + > + /* Allocate a new domain and set it on device pasid. */ > + domain = iommu_sva_domain_alloc(dev, mm); > + if (!domain) { > + ret = -ENOMEM; > + goto out_unlock; > + } > + > + ret = iommu_attach_device_pasid(domain, dev, mm->pasid); > + if (ret) > + goto out_free_domain; > + domain->bond.dev = dev; > + refcount_set(&domain->bond.users, 1); > + > +out_success: > + mutex_unlock(&iommu_sva_lock); > + return &domain->bond; > + > +out_free_domain: > + iommu_domain_free(domain); > +out_unlock: > + mutex_unlock(&iommu_sva_lock); > + > + return ERR_PTR(ret); > +} > +EXPORT_SYMBOL_GPL(iommu_sva_bind_device); > + > +/** > + * iommu_sva_unbind_device() - Remove a bond created with iommu_sva_bind_device > + * @handle: the handle returned by iommu_sva_bind_device() > + * > + * Put reference to a bond between device and address space. The device should > + * not be issuing any more transaction for this PASID. All outstanding page > + * requests for this PASID must have been flushed to the IOMMU. > + */ > +void iommu_sva_unbind_device(struct iommu_sva *handle) > +{ > + struct device *dev = handle->dev; > + struct iommu_domain *domain = > + container_of(handle, struct iommu_domain, bond); > + ioasid_t pasid = iommu_sva_get_pasid(handle); > + > + mutex_lock(&iommu_sva_lock); > + if (refcount_dec_and_test(&domain->bond.users)) { > + iommu_detach_device_pasid(domain, dev, pasid); > + iommu_domain_free(domain); > + } > + mutex_unlock(&iommu_sva_lock); > +} > +EXPORT_SYMBOL_GPL(iommu_sva_unbind_device); > + > +u32 iommu_sva_get_pasid(struct iommu_sva *handle) > +{ > + struct iommu_domain *domain = > + container_of(handle, struct iommu_domain, bond); > + > + return domain->mm->pasid; > +} > +EXPORT_SYMBOL_GPL(iommu_sva_get_pasid); > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index 10479c5e4d23..e1491eb3c7b6 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -2789,97 +2789,6 @@ bool iommu_dev_feature_enabled(struct device *dev, enum iommu_dev_features feat) > } > EXPORT_SYMBOL_GPL(iommu_dev_feature_enabled); > > -/** > - * iommu_sva_bind_device() - Bind a process address space to a device > - * @dev: the device > - * @mm: the mm to bind, caller must hold a reference to it > - * > - * Create a bond between device and address space, allowing the device to access > - * the mm using the returned PASID. If a bond already exists between @device and > - * @mm, it is returned and an additional reference is taken. Caller must call > - * iommu_sva_unbind_device() to release each reference. > - * > - * iommu_dev_enable_feature(dev, IOMMU_DEV_FEAT_SVA) must be called first, to > - * initialize the required SVA features. > - * > - * On error, returns an ERR_PTR value. > - */ > -struct iommu_sva * > -iommu_sva_bind_device(struct device *dev, struct mm_struct *mm) > -{ > - struct iommu_group *group; > - struct iommu_sva *handle = ERR_PTR(-EINVAL); > - const struct iommu_ops *ops = dev_iommu_ops(dev); > - > - if (!ops->sva_bind) > - return ERR_PTR(-ENODEV); > - > - group = iommu_group_get(dev); > - if (!group) > - return ERR_PTR(-ENODEV); > - > - /* Ensure device count and domain don't change while we're binding */ > - mutex_lock(&group->mutex); > - > - /* > - * To keep things simple, SVA currently doesn't support IOMMU groups > - * with more than one device. Existing SVA-capable systems are not > - * affected by the problems that required IOMMU groups (lack of ACS > - * isolation, device ID aliasing and other hardware issues). > - */ > - if (iommu_group_device_count(group) != 1) > - goto out_unlock; > - > - handle = ops->sva_bind(dev, mm); > - > -out_unlock: > - mutex_unlock(&group->mutex); > - iommu_group_put(group); > - > - return handle; > -} > -EXPORT_SYMBOL_GPL(iommu_sva_bind_device); > - > -/** > - * iommu_sva_unbind_device() - Remove a bond created with iommu_sva_bind_device > - * @handle: the handle returned by iommu_sva_bind_device() > - * > - * Put reference to a bond between device and address space. The device should > - * not be issuing any more transaction for this PASID. All outstanding page > - * requests for this PASID must have been flushed to the IOMMU. > - */ > -void iommu_sva_unbind_device(struct iommu_sva *handle) > -{ > - struct iommu_group *group; > - struct device *dev = handle->dev; > - const struct iommu_ops *ops = dev_iommu_ops(dev); > - > - if (!ops->sva_unbind) > - return; > - > - group = iommu_group_get(dev); > - if (!group) > - return; > - > - mutex_lock(&group->mutex); > - ops->sva_unbind(handle); > - mutex_unlock(&group->mutex); > - > - iommu_group_put(group); > -} > -EXPORT_SYMBOL_GPL(iommu_sva_unbind_device); > - > -u32 iommu_sva_get_pasid(struct iommu_sva *handle) > -{ > - const struct iommu_ops *ops = dev_iommu_ops(handle->dev); > - > - if (!ops->sva_get_pasid) > - return IOMMU_PASID_INVALID; > - > - return ops->sva_get_pasid(handle); > -} > -EXPORT_SYMBOL_GPL(iommu_sva_get_pasid); > - > /* > * Changes the default domain of an iommu group that has *only* one device > * > @@ -3366,3 +3275,31 @@ void iommu_detach_device_pasid(struct iommu_domain *domain, struct device *dev, > > iommu_group_put(group); > } > + > +/* > + * This is a variant of iommu_get_domain_for_dev(). It returns the existing > + * domain attached to pasid of a device. It's only for internal use of the > + * IOMMU subsystem. The caller must take care to avoid any possible > + * use-after-free case. > + */ > +struct iommu_domain * > +iommu_get_domain_for_dev_pasid(struct device *dev, ioasid_t pasid) > +{ > + struct iommu_domain *domain; > + struct iommu_group *group; > + > + if (!pasid_valid(pasid)) > + return NULL; > + > + group = iommu_group_get(dev); > + if (!group) > + return NULL; > + /* > + * The xarray protects its internal state with RCU. Hence the domain > + * obtained is either NULL or fully formed. > + */ > + domain = xa_load(&group->pasid_array, pasid); > + iommu_group_put(group); > + > + return domain; > +}
-- Regards, Yi Liu
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