Re: [PATCH 1/2] iommu/sva: Tighten SVA bind API with explicit flags

Lu Baolu
2021-04-09T12:24:34Z

Hi Jacob,

On 2021/4/9 1:08, Jacob Pan wrote:
> The void* drvdata parameter isn't really used in iommu_sva_bind_device()
> API, the current IDXD code "borrows" the drvdata for a VT-d private flag
> for supervisor SVA usage.
>
> Supervisor/Privileged mode request is a generic feature. It should be
> promoted from the VT-d vendor driver to the generic code.
>
> This patch replaces void* drvdata with a unsigned int flags parameter
> and adjusts callers accordingly.
>
> Link: https://lore.kernel.org/linux-iommu/YFhiMLR35WWMW%2FHu@myrica/
> Suggested-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> ---
> drivers/dma/idxd/cdev.c | 2 +-
> drivers/dma/idxd/init.c | 6 +++---
> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c | 2 +-
> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 4 ++--
> drivers/iommu/intel/Kconfig | 1 +
> drivers/iommu/intel/svm.c | 18 ++++++------------
> drivers/iommu/iommu.c | 9 ++++++---
> drivers/misc/uacce/uacce.c | 2 +-
> include/linux/intel-iommu.h | 2 +-
> include/linux/intel-svm.h | 17 ++---------------
> include/linux/iommu.h | 19 ++++++++++++++++---
> 11 files changed, 40 insertions(+), 42 deletions(-)
>
> diff --git a/drivers/dma/idxd/cdev.c b/drivers/dma/idxd/cdev.c
> index 0db9b82..21ec82b 100644
> --- a/drivers/dma/idxd/cdev.c
> +++ b/drivers/dma/idxd/cdev.c
> @@ -103,7 +103,7 @@ 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, 0);
> 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 085a0c3..cdc85f1 100644
> --- a/drivers/dma/idxd/init.c
> +++ b/drivers/dma/idxd/init.c
> @@ -300,13 +300,13 @@ static struct idxd_device *idxd_alloc(struct pci_dev *pdev)
>
> static int idxd_enable_system_pasid(struct idxd_device *idxd)
> {
> - int flags;
> + unsigned int flags;
> unsigned int pasid;
> struct iommu_sva *sva;
>
> - flags = SVM_FLAG_SUPERVISOR_MODE;
> + flags = IOMMU_SVA_BIND_SUPERVISOR;

With SVM_FLAG_SUPERVISOR_MODE removed, I guess

#include <linux/intel-svm.h>

in this file could be removed as well.

>
> - sva = iommu_sva_bind_device(&idxd->pdev->dev, NULL, &flags);
> + 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));
> 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 bb251ca..23e287e 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
> @@ -354,7 +354,7 @@ __arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm)
> }
>
> 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, unsigned int flags)
> {
> struct iommu_sva *handle;
> struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
> 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 f985817..b971d4d 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> @@ -711,7 +711,7 @@ 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);
> struct iommu_sva *arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm,
> - void *drvdata);
> + unsigned int flags);
> 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);
> @@ -742,7 +742,7 @@ static inline int arm_smmu_master_disable_sva(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, unsigned int flags)
> {
> return ERR_PTR(-ENODEV);
> }
> diff --git a/drivers/iommu/intel/Kconfig b/drivers/iommu/intel/Kconfig
> index 28a3d15..5415052 100644
> --- a/drivers/iommu/intel/Kconfig
> +++ b/drivers/iommu/intel/Kconfig
> @@ -41,6 +41,7 @@ config INTEL_IOMMU_SVM
> select PCI_PRI
> select MMU_NOTIFIER
> select IOASID
> + select IOMMU_SVA_LIB

Why?

> help
> Shared Virtual Memory (SVM) provides a facility for devices
> to access DMA resources through process address space by
> diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
> index 574a7e6..4b5f8b0 100644
> --- a/drivers/iommu/intel/svm.c
> +++ b/drivers/iommu/intel/svm.c
> @@ -486,12 +486,9 @@ intel_svm_bind_mm(struct device *dev, unsigned int flags,
> } else
> pasid_max = 1 << 20;
>
> - /* Bind supervisor PASID shuld have mm = NULL */
> - if (flags & SVM_FLAG_SUPERVISOR_MODE) {
> - if (!ecap_srs(iommu->ecap) || mm) {
> - pr_err("Supervisor PASID with user provided mm.\n");
> - return -EINVAL;
> - }
> + if ((flags & IOMMU_SVA_BIND_SUPERVISOR) && !ecap_srs(iommu->ecap)) {
> + pr_err("Supervisor PASID not supported.\n");
> + return -EINVAL;
> }
>
> if (!(flags & SVM_FLAG_PRIVATE_PASID)) {
> @@ -593,7 +590,7 @@ intel_svm_bind_mm(struct device *dev, unsigned int flags,
> ret = intel_pasid_setup_first_level(iommu, dev,
> mm ? mm->pgd : init_mm.pgd,
> svm->pasid, FLPT_DEFAULT_DID,
> - (mm ? 0 : PASID_FLAG_SUPERVISOR_MODE) |
> + (mm ? 0 : IOMMU_SVA_BIND_SUPERVISOR) |

NO. PASID_FLAG_SUPERVISOR_MODE is an internal flag to tell the helper
whether the SRE bit should be set in the PASID entry.

> (cpu_feature_enabled(X86_FEATURE_LA57) ?
> PASID_FLAG_FL5LP : 0));
> spin_unlock_irqrestore(&iommu->lock, iflags);
> @@ -620,7 +617,7 @@ intel_svm_bind_mm(struct device *dev, unsigned int flags,
> ret = intel_pasid_setup_first_level(iommu, dev,
> mm ? mm->pgd : init_mm.pgd,
> svm->pasid, FLPT_DEFAULT_DID,
> - (mm ? 0 : PASID_FLAG_SUPERVISOR_MODE) |
> + (mm ? 0 : IOMMU_SVA_BIND_SUPERVISOR) |

The same as above.

> (cpu_feature_enabled(X86_FEATURE_LA57) ?
> PASID_FLAG_FL5LP : 0));
> spin_unlock_irqrestore(&iommu->lock, iflags);
> @@ -1059,11 +1056,10 @@ static irqreturn_t prq_event_thread(int irq, void *d)
>
> #define to_intel_svm_dev(handle) container_of(handle, struct intel_svm_dev, sva)
> struct iommu_sva *
> -intel_svm_bind(struct device *dev, struct mm_struct *mm, void *drvdata)
> +intel_svm_bind(struct device *dev, struct mm_struct *mm, unsigned int flags)
> {
> struct iommu_sva *sva = ERR_PTR(-EINVAL);
> struct intel_svm_dev *sdev = NULL;
> - unsigned int flags = 0;
> int ret;
>
> /*
> @@ -1071,8 +1067,6 @@ intel_svm_bind(struct device *dev, struct mm_struct *mm, void *drvdata)
> * It will require shared SVM data structures, i.e. combine io_mm
> * and intel_svm etc.
> */
> - if (drvdata)
> - flags = *(unsigned int *)drvdata;
> mutex_lock(&pasid_mutex);
> ret = intel_svm_bind_mm(dev, flags, NULL, mm, &sdev);
> if (ret)
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index d0b0a15..bf0a20f 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -2962,6 +2962,7 @@ EXPORT_SYMBOL_GPL(iommu_aux_get_pasid);
> * 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
> + * @flags: options for the bind operation
> *
> * 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
> @@ -2974,7 +2975,7 @@ EXPORT_SYMBOL_GPL(iommu_aux_get_pasid);
> * 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, unsigned int flags)
> {
> struct iommu_group *group;
> struct iommu_sva *handle = ERR_PTR(-EINVAL);
> @@ -2987,6 +2988,9 @@ iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, void *drvdata)
> if (!group)
> return ERR_PTR(-ENODEV);
>
> + /* Supervisor SVA does not need the current mm */
> + if ((flags & IOMMU_SVA_BIND_SUPERVISOR) && mm)
> + return ERR_PTR(-EINVAL);
> /* Ensure device count and domain don't change while we're binding */
> mutex_lock(&group->mutex);
>
> @@ -2999,8 +3003,7 @@ 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, flags);
> out_unlock:
> mutex_unlock(&group->mutex);
> iommu_group_put(group);
> diff --git a/drivers/misc/uacce/uacce.c b/drivers/misc/uacce/uacce.c
> index d07af4e..27e0e04 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, 0);
> if (IS_ERR(handle))
> return PTR_ERR(handle);
>
> diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
> index 1bc46b8..cdff752 100644
> --- a/include/linux/intel-iommu.h
> +++ b/include/linux/intel-iommu.h
> @@ -757,7 +757,7 @@ int intel_svm_bind_gpasid(struct iommu_domain *domain, struct device *dev,
> struct iommu_gpasid_bind_data *data);
> int intel_svm_unbind_gpasid(struct device *dev, u32 pasid);
> struct iommu_sva *intel_svm_bind(struct device *dev, struct mm_struct *mm,
> - void *drvdata);
> + unsigned int flags);
> 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 39d368a..ef6b753 100644
> --- a/include/linux/intel-svm.h
> +++ b/include/linux/intel-svm.h
> @@ -30,30 +30,17 @@ struct svm_dev_ops {
> * if there is no other way to do so. It should be used sparingly, if at all.
> */
> #define SVM_FLAG_PRIVATE_PASID (1<<0)
> -
> -/*
> - * 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 (1<<1)
> /*
> * The SVM_FLAG_GUEST_MODE flag is used when a PASID bind is for guest
> * processes. Compared to the host bind, the primary differences are:
> * 1. mm life cycle management
> * 2. fault reporting
> */
> -#define SVM_FLAG_GUEST_MODE (1<<2)
> +#define SVM_FLAG_GUEST_MODE (1<<1)
> /*
> * The SVM_FLAG_GUEST_PASID flag is used when a guest has its own PASID space,
> * which requires guest and host PASID translation at both directions.
> */
> -#define SVM_FLAG_GUEST_PASID (1<<3)
> +#define SVM_FLAG_GUEST_PASID (1<<2)
>
> #endif /* __INTEL_SVM_H__ */
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 5e7fe51..a3fbaa2 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -166,6 +166,19 @@ enum iommu_dev_features {
>
> #ifdef CONFIG_IOMMU_API
>
> +/*
> + * The IOMMU_SVA_BIND_SUPERVISOR 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 IOMMU_SVA_BIND_SUPERVISOR BIT(0)
> +
> /**
> * struct iommu_iotlb_gather - Range information for a pending IOTLB flush
> *
> @@ -287,7 +300,7 @@ struct iommu_ops {
> int (*aux_get_pasid)(struct iommu_domain *domain, struct device *dev);
>
> struct iommu_sva *(*sva_bind)(struct device *dev, struct mm_struct *mm,
> - void *drvdata);
> + unsigned int flags);
> void (*sva_unbind)(struct iommu_sva *handle);
> u32 (*sva_get_pasid)(struct iommu_sva *handle);
>
> @@ -640,7 +653,7 @@ int iommu_aux_get_pasid(struct iommu_domain *domain, struct device *dev);
>
> struct iommu_sva *iommu_sva_bind_device(struct device *dev,
> struct mm_struct *mm,
> - void *drvdata);
> + unsigned int flags);
> void iommu_sva_unbind_device(struct iommu_sva *handle);
> u32 iommu_sva_get_pasid(struct iommu_sva *handle);
>
> @@ -1015,7 +1028,7 @@ iommu_aux_get_pasid(struct iommu_domain *domain, struct device *dev)
> }
>
> 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, unsigned int flags)
> {
> return NULL;
> }
>

Best regards,
baolu