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Date:   Tue, 13 Apr 2021 15:13:30 -0700
From:   Jacob Pan <jacob.jun.pan@linux.intel.com>
To:     Lu Baolu <baolu.lu@linux.intel.com>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        iommu@lists.linux-foundation.org, Joerg Roedel <joro@8bytes.org>,
        Jean-Philippe Brucker <jean-philippe@linaro.com>,
        Yi Liu <yi.l.liu@intel.com>, Raj Ashok <ashok.raj@intel.com>,
        "Tian, Kevin" <kevin.tian@intel.com>,
        Jason Gunthorpe <jgg@nvidia.com>,
        Dave Jiang <dave.jiang@intel.com>, wangzhou1@hisilicon.com,
        zhangfei.gao@linaro.org, vkoul@kernel.org,
        jacob.jun.pan@linux.intel.com
Subject: Re: [PATCH 1/2] iommu/sva: Tighten SVA bind API with explicit flags
Message-ID: <20210413151330.2fa6325c@jacob-builder>
In-Reply-To: <a015f183-7965-60d8-6f8a-646cb47e5eb6@linux.intel.com>
References: <1617901736-24788-1-git-send-email-jacob.jun.pan@linux.intel.com>
        <a015f183-7965-60d8-6f8a-646cb47e5eb6@linux.intel.com>
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Hi Baolu,
Thanks for the view.

On Fri, 9 Apr 2021 20:24:22 +0800, Lu Baolu <baolu.lu@linux.intel.com>
wrote:

> 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.
yes, good point.

> 
> >   
> > -	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?
Right, not needed. VT-d is not using iommu_sva_alloc/free_pasid() yet. I was
under the wrong impression that iommu_sva_bind_device is part of the
sva-lib.

> 
> >   	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.
> 
OK, will keep them separate.

> >   				(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.
> 
got it.

> >   						(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


Thanks,

Jacob