On Tue, 1 Sep 2020 19:03:23 +0200 Auger Eric <[email protected]> wrote:
> Hi Jacob, > > On 8/22/20 6:35 AM, Jacob Pan wrote: > > On Intel Scalable I/O Virtualization (SIOV) enabled platforms, IOMMU > > driver is one of the users of IOASIDs. In normal flow, callers will > > perform IOASID allocation, bind, unbind, and free in order. However, for > > guest SVA, IOASID free could come before unbind as guest is untrusted. > > This patch registers IOASID notification handler such that IOMMU driver > > can perform PASID teardown upon receiving an unexpected IOASID free > > event. > > > > Signed-off-by: Jacob Pan <[email protected]> > > --- > > drivers/iommu/intel/svm.c | 74 > > ++++++++++++++++++++++++++++++++++++++++++++- > > include/linux/intel-iommu.h | 2 ++ > > 2 files changed, 75 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c > > index 634e191ca2c3..600e3ae5b656 100644 > > --- a/drivers/iommu/intel/svm.c > > +++ b/drivers/iommu/intel/svm.c > > @@ -95,6 +95,72 @@ static inline bool intel_svm_capable(struct intel_iommu > > *iommu) > > return iommu->flags & VTD_FLAG_SVM_CAPABLE; > > } > > > > +#define pasid_lock_held() lock_is_held(&pasid_mutex.dep_map) > put after the pasid_mutex definition? yes, > > +static DEFINE_MUTEX(pasid_mutex); > > + > > +static void intel_svm_free_async_fn(struct work_struct *work) > > +{ > > + struct intel_svm *svm = container_of(work, struct intel_svm, work); > > + struct intel_svm_dev *sdev; > > + > > + /* > > + * Unbind all devices associated with this PASID which is > > + * being freed by other users such as VFIO. > > + */ > > + mutex_lock(&pasid_mutex); > > + list_for_each_entry_rcu(sdev, &svm->devs, list, pasid_lock_held()) { > > + /* Does not poison forward pointer */ > > + list_del_rcu(&sdev->list); > > + spin_lock(&svm->iommu->lock); > > + intel_pasid_tear_down_entry(svm->iommu, sdev->dev, > > + svm->pasid, true); > > + spin_unlock(&svm->iommu->lock); > > + kfree_rcu(sdev, rcu); > > + /* > > + * Free before unbind only happens with guest usaged > usaged? used. I meant host PASID used to back guest PASID. I will reword the comments: /* * Free before unbind can only happen with host PASIDs used for * guest SVM. We get here because ioasid_free is called with * outstanding references. So we need to drop the reference * such that the PASID can be reclaimed. Once refcount reaches * zero, IOASID core will detach the private data and erase the * IOASID entry. */ > > + * host PASIDs. IOASID free will detach private data > > + * and free the IOASID entry. > > + */ > > + ioasid_put(NULL, svm->pasid); > > + if (list_empty(&svm->devs)) > > + kfree(svm); > > + } > > + mutex_unlock(&pasid_mutex); > > +} > > + > > + > > +static int pasid_status_change(struct notifier_block *nb, > > + unsigned long code, void *data) > > +{ > > + struct ioasid_nb_args *args = (struct ioasid_nb_args *)data; > > + struct intel_svm *svm = (struct intel_svm *)args->pdata; > > + int ret = NOTIFY_DONE; > > + > > + if (code == IOASID_FREE) { > > + if (!svm) > > + goto done; > > + if (args->id != svm->pasid) { > > + pr_warn("Notify PASID does not match data %d : %d\n", > > + args->id, svm->pasid); > > + goto done; > > + } > > + schedule_work(&svm->work); > > + return NOTIFY_OK; > > + } > > +done: > > + return ret;> +} > > + > > +static struct notifier_block pasid_nb = { > > + .notifier_call = pasid_status_change, > > +}; > > + > > +void intel_svm_add_pasid_notifier(void) > > +{ > > + /* Listen to all PASIDs, not specific to a set */ > > + ioasid_register_notifier(NULL, &pasid_nb); > > +} > > + > > void intel_svm_check(struct intel_iommu *iommu) > > { > > if (!pasid_supported(iommu)) > > @@ -221,7 +287,6 @@ static const struct mmu_notifier_ops intel_mmuops = { > > .invalidate_range = intel_invalidate_range, > > }; > > > > -static DEFINE_MUTEX(pasid_mutex); > > static LIST_HEAD(global_svm_list); > > > > #define for_each_svm_dev(sdev, svm, d) \ > > @@ -342,7 +407,14 @@ int intel_svm_bind_gpasid(struct iommu_domain *domain, > > struct device *dev, > > svm->gpasid = data->gpasid; > > svm->flags |= SVM_FLAG_GUEST_PASID; > > } > > + svm->iommu = iommu; > > + /* > > + * Set up cleanup async work in case IOASID core notify us PASID > > + * is freed before unbind. > > + */ > > + INIT_WORK(&svm->work, intel_svm_free_async_fn); > > ioasid_attach_data(data->hpasid, svm); > > + ioasid_get(NULL, svm->pasid); > > INIT_LIST_HEAD_RCU(&svm->devs); > > mmput(svm->mm); > > } > > diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h > > index b1ed2f25f7c0..d36038e6ae0b 100644 > > --- a/include/linux/intel-iommu.h > > +++ b/include/linux/intel-iommu.h > > @@ -744,6 +744,7 @@ void intel_svm_unbind(struct iommu_sva *handle); > > int intel_svm_get_pasid(struct iommu_sva *handle); > > int intel_svm_page_response(struct device *dev, struct iommu_fault_event > > *evt, > > struct iommu_page_response *msg); > > +void intel_svm_add_pasid_notifier(void); > > > > struct svm_dev_ops; > > > > @@ -770,6 +771,7 @@ struct intel_svm { > > int gpasid; /* In case that guest PASID is different from host PASID */ > > struct list_head devs; > > struct list_head list; > > + struct work_struct work; /* For deferred clean up */ > > }; > > #else > > static inline void intel_svm_check(struct intel_iommu *iommu) {} > > > > Thanks > > Eric > > _______________________________________________ > iommu mailing list > [email protected] > https://lists.linuxfoundation.org/mailman/listinfo/iommu [Jacob Pan] _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
