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Subject: Re: [PATCH v11 01/13] vfio: VFIO_IOMMU_SET_PASID_TABLE
To:     Eric Auger <eric.auger@redhat.com>, <eric.auger.pro@gmail.com>,
        <iommu@lists.linux-foundation.org>, <linux-kernel@vger.kernel.org>,
        <kvm@vger.kernel.org>, <kvmarm@lists.cs.columbia.edu>,
        <will@kernel.org>, <joro@8bytes.org>, <maz@kernel.org>,
        <robin.murphy@arm.com>, <alex.williamson@redhat.com>
References: <20201116110030.32335-1-eric.auger@redhat.com>
 <20201116110030.32335-2-eric.auger@redhat.com>
CC:     <jean-philippe@linaro.org>, <jacob.jun.pan@linux.intel.com>,
        <nicoleotsuka@gmail.com>, <vivek.gautam@arm.com>,
        <yi.l.liu@intel.com>, <zhangfei.gao@linaro.org>
From:   Keqian Zhu <zhukeqian1@huawei.com>
Message-ID: <84a111da-1969-1701-9a6d-cae8d7c285c6@huawei.com>
Date:   Tue, 2 Feb 2021 20:34:35 +0800
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Hi Eric,

On 2020/11/16 19:00, Eric Auger wrote:
> From: "Liu, Yi L" <yi.l.liu@linux.intel.com>
> 
> This patch adds an VFIO_IOMMU_SET_PASID_TABLE ioctl
> which aims to pass the virtual iommu guest configuration
> to the host. This latter takes the form of the so-called
> PASID table.
> 
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Signed-off-by: Liu, Yi L <yi.l.liu@linux.intel.com>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> 
> ---
> v11 -> v12:
> - use iommu_uapi_set_pasid_table
> - check SET and UNSET are not set simultaneously (Zenghui)
> 
> v8 -> v9:
> - Merge VFIO_IOMMU_ATTACH/DETACH_PASID_TABLE into a single
>   VFIO_IOMMU_SET_PASID_TABLE ioctl.
> 
> v6 -> v7:
> - add a comment related to VFIO_IOMMU_DETACH_PASID_TABLE
> 
> v3 -> v4:
> - restore ATTACH/DETACH
> - add unwind on failure
> 
> v2 -> v3:
> - s/BIND_PASID_TABLE/SET_PASID_TABLE
> 
> v1 -> v2:
> - s/BIND_GUEST_STAGE/BIND_PASID_TABLE
> - remove the struct device arg
> ---
>  drivers/vfio/vfio_iommu_type1.c | 65 +++++++++++++++++++++++++++++++++
>  include/uapi/linux/vfio.h       | 19 ++++++++++
>  2 files changed, 84 insertions(+)
> 
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 67e827638995..87ddd9e882dc 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -2587,6 +2587,41 @@ static int vfio_iommu_iova_build_caps(struct vfio_iommu *iommu,
>  	return ret;
>  }
>  
> +static void
> +vfio_detach_pasid_table(struct vfio_iommu *iommu)
> +{
> +	struct vfio_domain *d;
> +
> +	mutex_lock(&iommu->lock);
> +	list_for_each_entry(d, &iommu->domain_list, next)
> +		iommu_detach_pasid_table(d->domain);
> +
> +	mutex_unlock(&iommu->lock);
> +}
> +
> +static int
> +vfio_attach_pasid_table(struct vfio_iommu *iommu, unsigned long arg)
> +{
> +	struct vfio_domain *d;
> +	int ret = 0;
> +
> +	mutex_lock(&iommu->lock);
> +
> +	list_for_each_entry(d, &iommu->domain_list, next) {
> +		ret = iommu_uapi_attach_pasid_table(d->domain, (void __user *)arg);
This design is not very clear to me. This assumes all iommu_domains share the same pasid table.

As I understand, it's reasonable when there is only one group in the domain, and only one domain in the vfio_iommu.
If more than one group in the vfio_iommu, the guest may put them into different guest iommu_domain, then they have different pasid table.

Is this the use scenario?

Thanks,
Keqian

> +		if (ret)
> +			goto unwind;
> +	}
> +	goto unlock;
> +unwind:
> +	list_for_each_entry_continue_reverse(d, &iommu->domain_list, next) {
> +		iommu_detach_pasid_table(d->domain);
> +	}
> +unlock:
> +	mutex_unlock(&iommu->lock);
> +	return ret;
> +}
> +
>  static int vfio_iommu_migration_build_caps(struct vfio_iommu *iommu,
>  					   struct vfio_info_cap *caps)
>  {
> @@ -2747,6 +2782,34 @@ static int vfio_iommu_type1_unmap_dma(struct vfio_iommu *iommu,
>  			-EFAULT : 0;
>  }
>  
> +static int vfio_iommu_type1_set_pasid_table(struct vfio_iommu *iommu,
> +					    unsigned long arg)
> +{
> +	struct vfio_iommu_type1_set_pasid_table spt;
> +	unsigned long minsz;
> +	int ret = -EINVAL;
> +
> +	minsz = offsetofend(struct vfio_iommu_type1_set_pasid_table, flags);
> +
> +	if (copy_from_user(&spt, (void __user *)arg, minsz))
> +		return -EFAULT;
> +
> +	if (spt.argsz < minsz)
> +		return -EINVAL;
> +
> +	if (spt.flags & VFIO_PASID_TABLE_FLAG_SET &&
> +	    spt.flags & VFIO_PASID_TABLE_FLAG_UNSET)
> +		return -EINVAL;
> +
> +	if (spt.flags & VFIO_PASID_TABLE_FLAG_SET)
> +		ret = vfio_attach_pasid_table(iommu, arg + minsz);
> +	else if (spt.flags & VFIO_PASID_TABLE_FLAG_UNSET) {
> +		vfio_detach_pasid_table(iommu);
> +		ret = 0;
> +	}
> +	return ret;
> +}
> +
>  static int vfio_iommu_type1_dirty_pages(struct vfio_iommu *iommu,
>  					unsigned long arg)
>  {
> @@ -2867,6 +2930,8 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
>  		return vfio_iommu_type1_unmap_dma(iommu, arg);
>  	case VFIO_IOMMU_DIRTY_PAGES:
>  		return vfio_iommu_type1_dirty_pages(iommu, arg);
> +	case VFIO_IOMMU_SET_PASID_TABLE:
> +		return vfio_iommu_type1_set_pasid_table(iommu, arg);
>  	default:
>  		return -ENOTTY;
>  	}
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index 2f313a238a8f..78ce3ce6c331 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -14,6 +14,7 @@
>  
>  #include <linux/types.h>
>  #include <linux/ioctl.h>
> +#include <linux/iommu.h>
>  
>  #define VFIO_API_VERSION	0
>  
> @@ -1180,6 +1181,24 @@ struct vfio_iommu_type1_dirty_bitmap_get {
>  
>  #define VFIO_IOMMU_DIRTY_PAGES             _IO(VFIO_TYPE, VFIO_BASE + 17)
>  
> +/*
> + * VFIO_IOMMU_SET_PASID_TABLE - _IOWR(VFIO_TYPE, VFIO_BASE + 22,
> + *			struct vfio_iommu_type1_set_pasid_table)
> + *
> + * The SET operation passes a PASID table to the host while the
> + * UNSET operation detaches the one currently programmed. Setting
> + * a table while another is already programmed replaces the old table.
> + */
> +struct vfio_iommu_type1_set_pasid_table {
> +	__u32	argsz;
> +	__u32	flags;
> +#define VFIO_PASID_TABLE_FLAG_SET	(1 << 0)
> +#define VFIO_PASID_TABLE_FLAG_UNSET	(1 << 1)
> +	struct iommu_pasid_table_config config; /* used on SET */
> +};
> +
> +#define VFIO_IOMMU_SET_PASID_TABLE	_IO(VFIO_TYPE, VFIO_BASE + 22)
> +
>  /* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */
>  
>  /*
>