Re: [PATCH v7 02/10] iommu: Remove SVM_FLAG_SUPERVISOR_MODE support

Jean-Philippe Brucker
2022-05-19T16:23:08Z

On Thu, May 19, 2022 at 03:20:39PM +0800, Lu Baolu wrote:
> The current kernel DMA with PASID support is based on the SVA with a flag
> SVM_FLAG_SUPERVISOR_MODE. The IOMMU driver binds the kernel memory address
> space to a PASID of the device. The device driver programs the device with
> kernel virtual address (KVA) for DMA access. There have been security and
> functional issues with this approach:
>
> - The lack of IOTLB synchronization upon kernel page table updates.
> (vmalloc, module/BPF loading, CONFIG_DEBUG_PAGEALLOC etc.)
> - Other than slight more protection, using kernel virtual address (KVA)
> has little advantage over physical address. There are also no use
> cases yet where DMA engines need kernel virtual addresses for in-kernel
> DMA.
>
> This removes SVM_FLAG_SUPERVISOR_MODE support from the IOMMU interface.
> The device drivers are suggested to handle kernel DMA with PASID through
> the kernel DMA APIs.
>
> The drvdata parameter in iommu_sva_bind_device() and all callbacks is not
> needed anymore. Cleanup them as well.
>
> Link: https://lore.kernel.org/linux-iommu/20210511194726.GP1002214@nvidia.com/
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

For the SMMU bits

Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>

> ---
> include/linux/intel-iommu.h | 3 +-
> include/linux/intel-svm.h | 13 -----
> include/linux/iommu.h | 8 +--
> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 5 +-
> drivers/dma/idxd/cdev.c | 2 +-
> drivers/dma/idxd/init.c | 24 +-------
> .../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c | 3 +-

> drivers/iommu/intel/svm.c | 57 +++++--------------
> drivers/iommu/iommu.c | 5 +-
> drivers/misc/uacce/uacce.c | 2 +-
> 10 files changed, 26 insertions(+), 96 deletions(-)
>
> diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
> index 4f29139bbfc3..df23300cfa88 100644
> --- a/include/linux/intel-iommu.h
> +++ b/include/linux/intel-iommu.h
> @@ -739,8 +739,7 @@ struct intel_iommu *device_to_iommu(struct device *dev, u8 *bus, u8 *devfn);
> extern void intel_svm_check(struct intel_iommu *iommu);
> extern int intel_svm_enable_prq(struct intel_iommu *iommu);
> extern int intel_svm_finish_prq(struct intel_iommu *iommu);
> -struct iommu_sva *intel_svm_bind(struct device *dev, struct mm_struct *mm,
> - void *drvdata);
> +struct iommu_sva *intel_svm_bind(struct device *dev, struct mm_struct *mm);
> void intel_svm_unbind(struct iommu_sva *handle);
> u32 intel_svm_get_pasid(struct iommu_sva *handle);
> int intel_svm_page_response(struct device *dev, struct iommu_fault_event *evt,
> diff --git a/include/linux/intel-svm.h b/include/linux/intel-svm.h
> index 207ef06ba3e1..f9a0d44f6fdb 100644
> --- a/include/linux/intel-svm.h
> +++ b/include/linux/intel-svm.h
> @@ -13,17 +13,4 @@
> #define PRQ_RING_MASK ((0x1000 << PRQ_ORDER) - 0x20)
> #define PRQ_DEPTH ((0x1000 << PRQ_ORDER) >> 5)
>
> -/*
> - * The SVM_FLAG_SUPERVISOR_MODE flag requests a PASID which can be used only
> - * for access to kernel addresses. No IOTLB flushes are automatically done
> - * for kernel mappings; it is valid only for access to the kernel's static
> - * 1:1 mapping of physical memory — not to vmalloc or even module mappings.
> - * A future API addition may permit the use of such ranges, by means of an
> - * explicit IOTLB flush call (akin to the DMA API's unmap method).
> - *
> - * It is unlikely that we will ever hook into flush_tlb_kernel_range() to
> - * do such IOTLB flushes automatically.
> - */
> -#define SVM_FLAG_SUPERVISOR_MODE BIT(0)
> -
> #endif /* __INTEL_SVM_H__ */
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index da423e87f248..0c358b7c583b 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -243,8 +243,7 @@ struct iommu_ops {
> int (*dev_enable_feat)(struct device *dev, enum iommu_dev_features f);
> int (*dev_disable_feat)(struct device *dev, enum iommu_dev_features f);
>
> - struct iommu_sva *(*sva_bind)(struct device *dev, struct mm_struct *mm,
> - void *drvdata);
> + struct iommu_sva *(*sva_bind)(struct device *dev, struct mm_struct *mm);
> void (*sva_unbind)(struct iommu_sva *handle);
> u32 (*sva_get_pasid)(struct iommu_sva *handle);
>
> @@ -667,8 +666,7 @@ 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 *drvdata);
> + struct mm_struct *mm);
> void iommu_sva_unbind_device(struct iommu_sva *handle);
> u32 iommu_sva_get_pasid(struct iommu_sva *handle);
>
> @@ -1010,7 +1008,7 @@ iommu_dev_disable_feature(struct device *dev, enum iommu_dev_features feat)
> }
>
> static inline struct iommu_sva *
> -iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, void *drvdata)
> +iommu_sva_bind_device(struct device *dev, struct mm_struct *mm)
> {
> return NULL;
> }
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> index cd48590ada30..d2ba86470c42 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> @@ -754,8 +754,7 @@ bool arm_smmu_master_sva_enabled(struct arm_smmu_master *master);
> int arm_smmu_master_enable_sva(struct arm_smmu_master *master);
> int arm_smmu_master_disable_sva(struct arm_smmu_master *master);
> bool arm_smmu_master_iopf_supported(struct arm_smmu_master *master);
> -struct iommu_sva *arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm,
> - void *drvdata);
> +struct iommu_sva *arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm);
> void arm_smmu_sva_unbind(struct iommu_sva *handle);
> u32 arm_smmu_sva_get_pasid(struct iommu_sva *handle);
> void arm_smmu_sva_notifier_synchronize(void);
> @@ -791,7 +790,7 @@ static inline bool arm_smmu_master_iopf_supported(struct arm_smmu_master *master
> }
>
> static inline struct iommu_sva *
> -arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm, void *drvdata)
> +arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm)
> {
> return ERR_PTR(-ENODEV);
> }
> diff --git a/drivers/dma/idxd/cdev.c b/drivers/dma/idxd/cdev.c
> index b9b2b4a4124e..312ec37ebf91 100644
> --- a/drivers/dma/idxd/cdev.c
> +++ b/drivers/dma/idxd/cdev.c
> @@ -100,7 +100,7 @@ static int idxd_cdev_open(struct inode *inode, struct file *filp)
> filp->private_data = ctx;
>
> if (device_pasid_enabled(idxd)) {
> - sva = iommu_sva_bind_device(dev, current->mm, NULL);
> + sva = iommu_sva_bind_device(dev, current->mm);
> if (IS_ERR(sva)) {
> rc = PTR_ERR(sva);
> dev_err(dev, "pasid allocation failed: %d\n", rc);
> diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
> index 993a5dcca24f..1fd80c63248a 100644
> --- a/drivers/dma/idxd/init.c
> +++ b/drivers/dma/idxd/init.c
> @@ -466,29 +466,7 @@ static struct idxd_device *idxd_alloc(struct pci_dev *pdev, struct idxd_driver_d
>
> static int idxd_enable_system_pasid(struct idxd_device *idxd)
> {
> - int flags;
> - unsigned int pasid;
> - struct iommu_sva *sva;
> -
> - flags = SVM_FLAG_SUPERVISOR_MODE;
> -
> - sva = iommu_sva_bind_device(&idxd->pdev->dev, NULL, &flags);
> - if (IS_ERR(sva)) {
> - dev_warn(&idxd->pdev->dev,
> - "iommu sva bind failed: %ld\n", PTR_ERR(sva));
> - return PTR_ERR(sva);
> - }
> -
> - pasid = iommu_sva_get_pasid(sva);
> - if (pasid == IOMMU_PASID_INVALID) {
> - iommu_sva_unbind_device(sva);
> - return -ENODEV;
> - }
> -
> - idxd->sva = sva;
> - idxd->pasid = pasid;
> - dev_dbg(&idxd->pdev->dev, "system pasid: %u\n", pasid);
> - return 0;
> + return -EOPNOTSUPP;
> }
>
> static void idxd_disable_system_pasid(struct idxd_device *idxd)
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> index 1ef7bbb4acf3..f155d406c5d5 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> @@ -367,8 +367,7 @@ __arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm)
> return ERR_PTR(ret);
> }
>
> -struct iommu_sva *
> -arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm, void *drvdata)
> +struct iommu_sva *arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm)
> {
> struct iommu_sva *handle;
> struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
> diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
> index 7ee37d996e15..d04880a291c3 100644
> --- a/drivers/iommu/intel/svm.c
> +++ b/drivers/iommu/intel/svm.c
> @@ -313,8 +313,7 @@ static int pasid_to_svm_sdev(struct device *dev, unsigned int pasid,
> return 0;
> }
>
> -static int intel_svm_alloc_pasid(struct device *dev, struct mm_struct *mm,
> - unsigned int flags)
> +static int intel_svm_alloc_pasid(struct device *dev, struct mm_struct *mm)
> {
> ioasid_t max_pasid = dev_is_pci(dev) ?
> pci_max_pasids(to_pci_dev(dev)) : intel_pasid_max_id;
> @@ -324,8 +323,7 @@ static int intel_svm_alloc_pasid(struct device *dev, struct mm_struct *mm,
>
> static struct iommu_sva *intel_svm_bind_mm(struct intel_iommu *iommu,
> struct device *dev,
> - struct mm_struct *mm,
> - unsigned int flags)
> + struct mm_struct *mm)
> {
> struct device_domain_info *info = dev_iommu_priv_get(dev);
> unsigned long iflags, sflags;
> @@ -341,22 +339,18 @@ static struct iommu_sva *intel_svm_bind_mm(struct intel_iommu *iommu,
>
> svm->pasid = mm->pasid;
> svm->mm = mm;
> - svm->flags = flags;
> INIT_LIST_HEAD_RCU(&svm->devs);
>
> - if (!(flags & SVM_FLAG_SUPERVISOR_MODE)) {
> - svm->notifier.ops = &intel_mmuops;
> - ret = mmu_notifier_register(&svm->notifier, mm);
> - if (ret) {
> - kfree(svm);
> - return ERR_PTR(ret);
> - }
> + svm->notifier.ops = &intel_mmuops;
> + ret = mmu_notifier_register(&svm->notifier, mm);
> + if (ret) {
> + kfree(svm);
> + return ERR_PTR(ret);
> }
>
> ret = pasid_private_add(svm->pasid, svm);
> if (ret) {
> - if (svm->notifier.ops)
> - mmu_notifier_unregister(&svm->notifier, mm);
> + mmu_notifier_unregister(&svm->notifier, mm);
> kfree(svm);
> return ERR_PTR(ret);
> }
> @@ -391,9 +385,7 @@ static struct iommu_sva *intel_svm_bind_mm(struct intel_iommu *iommu,
> }
>
> /* Setup the pasid table: */
> - sflags = (flags & SVM_FLAG_SUPERVISOR_MODE) ?
> - PASID_FLAG_SUPERVISOR_MODE : 0;
> - sflags |= cpu_feature_enabled(X86_FEATURE_LA57) ? PASID_FLAG_FL5LP : 0;
> + sflags = cpu_feature_enabled(X86_FEATURE_LA57) ? PASID_FLAG_FL5LP : 0;
> spin_lock_irqsave(&iommu->lock, iflags);
> ret = intel_pasid_setup_first_level(iommu, dev, mm->pgd, mm->pasid,
> FLPT_DEFAULT_DID, sflags);
> @@ -410,8 +402,7 @@ static struct iommu_sva *intel_svm_bind_mm(struct intel_iommu *iommu,
> kfree(sdev);
> free_svm:
> if (list_empty(&svm->devs)) {
> - if (svm->notifier.ops)
> - mmu_notifier_unregister(&svm->notifier, mm);
> + mmu_notifier_unregister(&svm->notifier, mm);
> pasid_private_remove(mm->pasid);
> kfree(svm);
> }
> @@ -767,7 +758,7 @@ static irqreturn_t prq_event_thread(int irq, void *d)
> * to unbind the mm while any page faults are outstanding.
> */
> svm = pasid_private_find(req->pasid);
> - if (IS_ERR_OR_NULL(svm) || (svm->flags & SVM_FLAG_SUPERVISOR_MODE))
> + if (IS_ERR_OR_NULL(svm))
> goto bad_req;
> }
>
> @@ -818,40 +809,20 @@ static irqreturn_t prq_event_thread(int irq, void *d)
> return IRQ_RETVAL(handled);
> }
>
> -struct iommu_sva *intel_svm_bind(struct device *dev, struct mm_struct *mm, void *drvdata)
> +struct iommu_sva *intel_svm_bind(struct device *dev, struct mm_struct *mm)
> {
> struct intel_iommu *iommu = device_to_iommu(dev, NULL, NULL);
> - unsigned int flags = 0;
> struct iommu_sva *sva;
> int ret;
>
> - if (drvdata)
> - flags = *(unsigned int *)drvdata;
> -
> - if (flags & SVM_FLAG_SUPERVISOR_MODE) {
> - if (!ecap_srs(iommu->ecap)) {
> - dev_err(dev, "%s: Supervisor PASID not supported\n",
> - iommu->name);
> - return ERR_PTR(-EOPNOTSUPP);
> - }
> -
> - if (mm) {
> - dev_err(dev, "%s: Supervisor PASID with user provided mm\n",
> - iommu->name);
> - return ERR_PTR(-EINVAL);
> - }
> -
> - mm = &init_mm;
> - }
> -
> mutex_lock(&pasid_mutex);
> - ret = intel_svm_alloc_pasid(dev, mm, flags);
> + ret = intel_svm_alloc_pasid(dev, mm);
> if (ret) {
> mutex_unlock(&pasid_mutex);
> return ERR_PTR(ret);
> }
>
> - sva = intel_svm_bind_mm(iommu, dev, mm, flags);
> + sva = intel_svm_bind_mm(iommu, dev, mm);
> mutex_unlock(&pasid_mutex);
>
> return sva;
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 847ad47a2dfd..9955f58bd08c 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -2768,7 +2768,6 @@ 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
> - * @drvdata: opaque data pointer to pass to bind callback
> *
> * 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
> @@ -2781,7 +2780,7 @@ EXPORT_SYMBOL_GPL(iommu_dev_feature_enabled);
> * On error, returns an ERR_PTR value.
> */
> struct iommu_sva *
> -iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, void *drvdata)
> +iommu_sva_bind_device(struct device *dev, struct mm_struct *mm)
> {
> struct iommu_group *group;
> struct iommu_sva *handle = ERR_PTR(-EINVAL);
> @@ -2806,7 +2805,7 @@ iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, void *drvdata)
> if (iommu_group_device_count(group) != 1)
> goto out_unlock;
>
> - handle = ops->sva_bind(dev, mm, drvdata);
> + handle = ops->sva_bind(dev, mm);
>
> out_unlock:
> mutex_unlock(&group->mutex);
> diff --git a/drivers/misc/uacce/uacce.c b/drivers/misc/uacce/uacce.c
> index 281c54003edc..3238a867ea51 100644
> --- a/drivers/misc/uacce/uacce.c
> +++ b/drivers/misc/uacce/uacce.c
> @@ -99,7 +99,7 @@ static int uacce_bind_queue(struct uacce_device *uacce, struct uacce_queue *q)
> if (!(uacce->flags & UACCE_DEV_SVA))
> return 0;
>
> - handle = iommu_sva_bind_device(uacce->parent, current->mm, NULL);
> + handle = iommu_sva_bind_device(uacce->parent, current->mm);
> if (IS_ERR(handle))
> return PTR_ERR(handle);
>
> --
> 2.25.1
>