RE: [PATCH v8 23/29] vfio: VFIO_IOMMU_CACHE_INVALIDATE

[Liu, Yi L]

Hi Eric,

> From: Eric Auger [mailto:eric.auger@xxxxxxxxxx]
> Sent: Monday, May 27, 2019 12:10 AM
> Subject: [PATCH v8 23/29] vfio: VFIO_IOMMU_CACHE_INVALIDATE
> 
> From: "Liu, Yi L" <yi.l.liu@xxxxxxxxxxxxxxx>
> 
> When the guest "owns" the stage 1 translation structures,  the host IOMMU driver
> has no knowledge of caching structure updates unless the guest invalidation
> requests are trapped and passed down to the host.
> 
> This patch adds the VFIO_IOMMU_CACHE_INVALIDATE ioctl with aims at
> propagating guest stage1 IOMMU cache invalidations to the host.
> 
> Signed-off-by: Liu, Yi L <yi.l.liu@xxxxxxxxxxxxxxx>
> Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
> 
> ---
> v6 -> v7:
> - Use iommu_capsule struct
> - renamed vfio_iommu_for_each_dev into vfio_iommu_lookup_dev
>   due to checkpatch error related to for_each_dev suffix
> 
> v2 -> v3:
> - introduce vfio_iommu_for_each_dev back in this patch
> 
> v1 -> v2:
> - s/TLB/CACHE
> - remove vfio_iommu_task usage
> - commit message rewording
> ---
>  drivers/vfio/vfio_iommu_type1.c | 55 +++++++++++++++++++++++++++++++++
>  include/uapi/linux/vfio.h       | 13 ++++++++
>  2 files changed, 68 insertions(+)
> 
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index b2d609d6fe83..6fda4fbc9bfa 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -120,6 +120,34 @@ struct vfio_regions {
>  #define IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu)	\
>  					(!list_empty(&iommu->domain_list))
> 
> +struct domain_capsule {
> +	struct iommu_domain *domain;
> +	void *data;
> +};
> +
> +/* iommu->lock must be held */
> +static int
> +vfio_iommu_lookup_dev(struct vfio_iommu *iommu,
> +		      int (*fn)(struct device *dev, void *data),
> +		      void *data)
> +{
> +	struct domain_capsule dc = {.data = data};
> +	struct vfio_domain *d;
> +	struct vfio_group *g;
> +	int ret = 0;
> +
> +	list_for_each_entry(d, &iommu->domain_list, next) {
> +		dc.domain = d->domain;
> +		list_for_each_entry(g, &d->group_list, next) {
> +			ret = iommu_group_for_each_dev(g->iommu_group,
> +						       &dc, fn);
> +			if (ret)
> +				break;
> +		}
> +	}
> +	return ret;
> +}
> +
>  static int put_pfn(unsigned long pfn, int prot);
> 
>  /*
> @@ -1795,6 +1823,15 @@ vfio_attach_pasid_table(struct vfio_iommu *iommu,
>  	return ret;
>  }
> 
> +static int vfio_cache_inv_fn(struct device *dev, void *data) {
> +	struct domain_capsule *dc = (struct domain_capsule *)data;
> +	struct vfio_iommu_type1_cache_invalidate *ustruct =
> +		(struct vfio_iommu_type1_cache_invalidate *)dc->data;
> +
> +	return iommu_cache_invalidate(dc->domain, dev, &ustruct->info); }
> +
>  static long vfio_iommu_type1_ioctl(void *iommu_data,
>  				   unsigned int cmd, unsigned long arg)  { @@ -
> 1881,6 +1918,24 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
>  	} else if (cmd == VFIO_IOMMU_DETACH_PASID_TABLE) {
>  		vfio_detach_pasid_table(iommu);
>  		return 0;
> +	} else if (cmd == VFIO_IOMMU_CACHE_INVALIDATE) {
> +		struct vfio_iommu_type1_cache_invalidate ustruct;
> +		int ret;
> +
> +		minsz = offsetofend(struct vfio_iommu_type1_cache_invalidate,
> +				    info);
> +
> +		if (copy_from_user(&ustruct, (void __user *)arg, minsz))
> +			return -EFAULT;
> +
> +		if (ustruct.argsz < minsz || ustruct.flags)

May remove the flags field?

> +			return -EINVAL;
> +
> +		mutex_lock(&iommu->lock);
> +		ret = vfio_iommu_lookup_dev(iommu, vfio_cache_inv_fn,
> +					    &ustruct);
> +		mutex_unlock(&iommu->lock);
> +		return ret;
>  	}
> 
>  	return -ENOTTY;
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h index
> 4316dd8cb5b5..055aa9b9745a 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -785,6 +785,19 @@ struct vfio_iommu_type1_attach_pasid_table {
>   */
>  #define VFIO_IOMMU_DETACH_PASID_TABLE	_IO(VFIO_TYPE, VFIO_BASE + 23)
> 
> +/**
> + * VFIO_IOMMU_CACHE_INVALIDATE - _IOWR(VFIO_TYPE, VFIO_BASE + 24,
> + *			struct vfio_iommu_type1_cache_invalidate)
> + *
> + * Propagate guest IOMMU cache invalidation to the host.
> + */
> +struct vfio_iommu_type1_cache_invalidate {
> +	__u32   argsz;
> +	__u32   flags;

Looks like there is no more usage on "flags". is it?

Regards,
Yi Liu

> +	struct iommu_cache_invalidate_info info; };
> +#define VFIO_IOMMU_CACHE_INVALIDATE      _IO(VFIO_TYPE, VFIO_BASE + 24)
> +
>  /* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */
> 
>  /*
> --
> 2.20.1