Re: [PATCH 15/17] iommu: remove DOMAIN_ATTR_NESTING

[Auger Eric <eric.auger@redhat.com>]

Hi Christoph,

On 3/1/21 9:42 AM, Christoph Hellwig wrote:
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 40 ++++++---------------
>  drivers/iommu/arm/arm-smmu/arm-smmu.c       | 30 ++++++++++------
>  drivers/iommu/intel/iommu.c                 | 28 +++++----------
>  drivers/iommu/iommu.c                       |  8 +++++
>  drivers/vfio/vfio_iommu_type1.c             |  5 +--
>  include/linux/iommu.h                       |  4 ++-
>  6 files changed, 50 insertions(+), 65 deletions(-)

As mentionned by Robin, there are series planning to use
DOMAIN_ATTR_NESTING to get info about the nested caps of the iommu (ARM
and Intel):

[Patch v8 00/10] vfio: expose virtual Shared Virtual Addressing to VMs
patches 1, 2, 3

Is the plan to introduce a new domain_get_nesting_info ops then?

Thanks

Eric	


> 
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> index bf96172e8c1f71..8e6fee3ea454d3 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -2466,41 +2466,21 @@ static void arm_smmu_dma_enable_flush_queue(struct iommu_domain *domain)
>  	to_smmu_domain(domain)->non_strict = true;
>  }
>  
> -static int arm_smmu_domain_set_attr(struct iommu_domain *domain,
> -				    enum iommu_attr attr, void *data)
> +static int arm_smmu_domain_enable_nesting(struct iommu_domain *domain)
>  {
> -	int ret = 0;
>  	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
> +	int ret = -EPERM;
>  
> -	mutex_lock(&smmu_domain->init_mutex);
> +	if (domain->type != IOMMU_DOMAIN_UNMANAGED)
> +		return -EINVAL;
>  
> -	switch (domain->type) {
> -	case IOMMU_DOMAIN_UNMANAGED:
> -		switch (attr) {
> -		case DOMAIN_ATTR_NESTING:
> -			if (smmu_domain->smmu) {
> -				ret = -EPERM;
> -				goto out_unlock;
> -			}
> -
> -			if (*(int *)data)
> -				smmu_domain->stage = ARM_SMMU_DOMAIN_NESTED;
> -			else
> -				smmu_domain->stage = ARM_SMMU_DOMAIN_S1;
> -			break;
> -		default:
> -			ret = -ENODEV;
> -		}
> -		break;
> -	case IOMMU_DOMAIN_DMA:
> -		ret = -ENODEV;
> -		break;
> -	default:
> -		ret = -EINVAL;
> +	mutex_lock(&smmu_domain->init_mutex);
> +	if (!smmu_domain->smmu) {
> +		smmu_domain->stage = ARM_SMMU_DOMAIN_NESTED;
> +		ret = 0;
>  	}
> -
> -out_unlock:
>  	mutex_unlock(&smmu_domain->init_mutex);
> +
>  	return ret;
>  }
>  
> @@ -2603,7 +2583,7 @@ static struct iommu_ops arm_smmu_ops = {
>  	.device_group		= arm_smmu_device_group,
>  	.dma_use_flush_queue	= arm_smmu_dma_use_flush_queue,
>  	.dma_enable_flush_queue	= arm_smmu_dma_enable_flush_queue,
> -	.domain_set_attr	= arm_smmu_domain_set_attr,
> +	.domain_enable_nesting	= arm_smmu_domain_enable_nesting,
>  	.of_xlate		= arm_smmu_of_xlate,
>  	.get_resv_regions	= arm_smmu_get_resv_regions,
>  	.put_resv_regions	= generic_iommu_put_resv_regions,
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> index e7893e96f5177a..2e17d990d04481 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> @@ -1497,6 +1497,24 @@ static void arm_smmu_dma_enable_flush_queue(struct iommu_domain *domain)
>  	to_smmu_domain(domain)->pgtbl_cfg.quirks |= IO_PGTABLE_QUIRK_NON_STRICT;
>  }
>  
> +static int arm_smmu_domain_enable_nesting(struct iommu_domain *domain)
> +{
> +	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
> +	int ret = -EPERM;
> +	
> +	if (domain->type != IOMMU_DOMAIN_UNMANAGED)
> +		return -EINVAL;
> +
> +	mutex_lock(&smmu_domain->init_mutex);
> +	if (!smmu_domain->smmu) {
> +		smmu_domain->stage = ARM_SMMU_DOMAIN_NESTED;
> +		ret = 0;
> +	}
> +	mutex_unlock(&smmu_domain->init_mutex);
> +
> +	return ret;
> +}
> +
>  static int arm_smmu_domain_set_attr(struct iommu_domain *domain,
>  				    enum iommu_attr attr, void *data)
>  {
> @@ -1508,17 +1526,6 @@ static int arm_smmu_domain_set_attr(struct iommu_domain *domain,
>  	switch(domain->type) {
>  	case IOMMU_DOMAIN_UNMANAGED:
>  		switch (attr) {
> -		case DOMAIN_ATTR_NESTING:
> -			if (smmu_domain->smmu) {
> -				ret = -EPERM;
> -				goto out_unlock;
> -			}
> -
> -			if (*(int *)data)
> -				smmu_domain->stage = ARM_SMMU_DOMAIN_NESTED;
> -			else
> -				smmu_domain->stage = ARM_SMMU_DOMAIN_S1;
> -			break;
>  		case DOMAIN_ATTR_IO_PGTABLE_CFG: {
>  			struct io_pgtable_domain_attr *pgtbl_cfg = data;
>  
> @@ -1603,6 +1610,7 @@ static struct iommu_ops arm_smmu_ops = {
>  	.dma_use_flush_queue	= arm_smmu_dma_use_flush_queue,
>  	.dma_enable_flush_queue	= arm_smmu_dma_enable_flush_queue,
>  	.domain_set_attr	= arm_smmu_domain_set_attr,
> +	.domain_enable_nesting	= arm_smmu_domain_enable_nesting,
>  	.of_xlate		= arm_smmu_of_xlate,
>  	.get_resv_regions	= arm_smmu_get_resv_regions,
>  	.put_resv_regions	= generic_iommu_put_resv_regions,
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index eaa80c33f4bc91..0f1374d6612a60 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -5423,32 +5423,22 @@ static bool intel_iommu_is_attach_deferred(struct iommu_domain *domain,
>  }
>  
>  static int
> -intel_iommu_domain_set_attr(struct iommu_domain *domain,
> -			    enum iommu_attr attr, void *data)
> +intel_iommu_domain_enable_nesting(struct iommu_domain *domain)
>  {
>  	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
>  	unsigned long flags;
> -	int ret = 0;
> +	int ret = -ENODEV;
>  
>  	if (domain->type != IOMMU_DOMAIN_UNMANAGED)
>  		return -EINVAL;
>  
> -	switch (attr) {
> -	case DOMAIN_ATTR_NESTING:
> -		spin_lock_irqsave(&device_domain_lock, flags);
> -		if (nested_mode_support() &&
> -		    list_empty(&dmar_domain->devices)) {
> -			dmar_domain->flags |= DOMAIN_FLAG_NESTING_MODE;
> -			dmar_domain->flags &= ~DOMAIN_FLAG_USE_FIRST_LEVEL;
> -		} else {
> -			ret = -ENODEV;
> -		}
> -		spin_unlock_irqrestore(&device_domain_lock, flags);
> -		break;
> -	default:
> -		ret = -EINVAL;
> -		break;
> +	spin_lock_irqsave(&device_domain_lock, flags);
> +	if (nested_mode_support() && list_empty(&dmar_domain->devices)) {
> +		dmar_domain->flags |= DOMAIN_FLAG_NESTING_MODE;
> +		dmar_domain->flags &= ~DOMAIN_FLAG_USE_FIRST_LEVEL;
> +		ret = 0;
>  	}
> +	spin_unlock_irqrestore(&device_domain_lock, flags);
>  
>  	return ret;
>  }
> @@ -5556,7 +5546,7 @@ const struct iommu_ops intel_iommu_ops = {
>  	.domain_alloc		= intel_iommu_domain_alloc,
>  	.domain_free		= intel_iommu_domain_free,
>  	.dma_use_flush_queue	= intel_iommu_dma_use_flush_queue,
> -	.domain_set_attr	= intel_iommu_domain_set_attr,
> +	.domain_enable_nesting	= intel_iommu_domain_enable_nesting,
>  	.attach_dev		= intel_iommu_attach_device,
>  	.detach_dev		= intel_iommu_detach_device,
>  	.aux_attach_dev		= intel_iommu_aux_attach_device,
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 0f12c4d58cdc42..2e9e058501a953 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -2685,6 +2685,14 @@ int iommu_domain_set_attr(struct iommu_domain *domain,
>  }
>  EXPORT_SYMBOL_GPL(iommu_domain_set_attr);
>  
> +int iommu_domain_enable_nesting(struct iommu_domain *domain)
> +{
> +	if (!domain->ops->domain_enable_nesting)
> +		return -EINVAL;
> +	return domain->ops->domain_enable_nesting(domain);
> +}
> +EXPORT_SYMBOL_GPL(iommu_domain_enable_nesting);
> +
>  void iommu_get_resv_regions(struct device *dev, struct list_head *list)
>  {
>  	const struct iommu_ops *ops = dev->bus->iommu_ops;
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index c8e57f22f421c5..9cea4d80dd66ed 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -2320,10 +2320,7 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
>  	}
>  
>  	if (iommu->nesting) {
> -		int attr = 1;
> -
> -		ret = iommu_domain_set_attr(domain->domain, DOMAIN_ATTR_NESTING,
> -					    &attr);
> +		ret = iommu_domain_enable_nesting(domain->domain);
>  		if (ret)
>  			goto out_domain;
>  	}
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index f30de33c6ff56e..aed88aa3bd3edf 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -107,7 +107,6 @@ enum iommu_cap {
>   */
>  
>  enum iommu_attr {
> -	DOMAIN_ATTR_NESTING,	/* two stages of translation */
>  	DOMAIN_ATTR_IO_PGTABLE_CFG,
>  	DOMAIN_ATTR_MAX,
>  };
> @@ -196,6 +195,7 @@ struct iommu_iotlb_gather {
>   * @dma_use_flush_queue: Returns %true if a DMA flush queue is used
>   * @dma_enable_flush_queue: Try to enable the DMA flush queue
>   * @domain_set_attr: Change domain attributes
> + * @domain_enable_nesting: Enable nesting
>   * @get_resv_regions: Request list of reserved regions for a device
>   * @put_resv_regions: Free list of reserved regions for a device
>   * @apply_resv_region: Temporary helper call-back for iova reserved ranges
> @@ -248,6 +248,7 @@ struct iommu_ops {
>  	void (*dma_enable_flush_queue)(struct iommu_domain *domain);
>  	int (*domain_set_attr)(struct iommu_domain *domain,
>  			       enum iommu_attr attr, void *data);
> +	int (*domain_enable_nesting)(struct iommu_domain *domain);
>  
>  	/* Request/Free a list of reserved regions for a device */
>  	void (*get_resv_regions)(struct device *dev, struct list_head *list);
> @@ -494,6 +495,7 @@ extern struct iommu_domain *iommu_group_default_domain(struct iommu_group *);
>  bool iommu_dma_use_flush_queue(struct iommu_domain *domain);
>  extern int iommu_domain_set_attr(struct iommu_domain *domain, enum iommu_attr,
>  				 void *data);
> +int iommu_domain_enable_nesting(struct iommu_domain *domain);
>  
>  extern int report_iommu_fault(struct iommu_domain *domain, struct device *dev,
>  			      unsigned long iova, int flags);
>