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Date:   Wed, 15 Mar 2023 17:59:34 -0700
From:   Nicolin Chen <nicolinc@nvidia.com>
To:     Jason Gunthorpe <jgg@nvidia.com>
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Subject: Re: [PATCH v1 02/14] iommufd: Add nesting related data structures
 for ARM SMMUv3
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On Fri, Mar 10, 2023 at 12:06:18PM -0400, Jason Gunthorpe wrote:
> On Thu, Mar 09, 2023 at 08:50:52PM -0800, Nicolin Chen wrote:
> > On Thu, Mar 09, 2023 at 10:48:50AM -0400, Jason Gunthorpe wrote:
> > 
> > > Nicolin, I think we should tweak the uAPI here so that the
> > > invalidation opaque data has a format tagged on its own, instead of
> > > re-using the HWPT tag. Ie you can have a ARM SMMUv3 invalidate type
> > > tag and also a virtio-viommu invalidate type tag.
> > 
> > The invalidation tage is shared with the hwpt allocation. Does
> > it mean that virtio-iommu won't have it's own allocation tag?
> 
> We probably shouldn't assume it will

In that case, why do have need an invalidation tag/type on its
own? Can't we use an IOMMU_HWPT_TYPE_VIRTIO tag for allocation
and invalidation together for virtio?

Or did you mean that we should define a flag inside the data
structure like this?

struct iommu_hwpt_invalidate_arm_smmuv3 {
#define IOMMU_SMMUV3_CMDQ_TLBI_VA_LEAF  (1 << 0)
#define IOMMU_SMMUV3_FORMAT_VIRTIO	(1 << 63)
	__u64 flags;
}

Thanks
Nic