From: Jason Gunthorpe <jgg@ziepe.ca>
To: Jacob Pan <jacob.pan@linux.microsoft.com>
Cc: Mostafa Saleh <smostafa@google.com>,
iommu@lists.linux.dev, Nicolin Chen <nicolinc@nvidia.com>,
Kevin Tian <kevin.tian@intel.com>, Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>, Wei Liu <wei.liu@kernel.org>,
"K . Y . Srinivasan" <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Dexuan Cui <decui@microsoft.com>, Long Li <longli@microsoft.com>,
linux-hyperv@vger.kernel.org, Joerg Roedel <joro@8bytes.org>,
Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
Vasant Hegde <vasant.hegde@amd.com>,
Arnd Bergmann <arnd@arndb.de>,
linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
"Aneesh Kumar K . V" <aneesh.kumar@kernel.org>,
Mukesh Rathor <mukeshrathor@microsoft.com>,
John Starks <John.Starks@microsoft.com>,
Souradeep Chakrabarti <schakrabarti@microsoft.com>,
Yu Zhang <zhangyu1@linux.microsoft.com>,
Easwar Hariharan <eahariha@linux.microsoft.com>,
Alex Williamson <alex@shazbot.org>
Subject: Re: [PATCH RFC 1/9] iommu: Introduce external attach domain type
Date: Mon, 9 Nov 2026 20:52:59 -0400 [thread overview]
Message-ID: <20261110005259.GU663069@ziepe.ca> (raw)
In-Reply-To: <20261106130352.0000638d@linux.microsoft.com>
On Fri, Nov 06, 2026 at 01:03:52PM -0800, Jacob Pan wrote:
> I am not stating that it will break UAPI because of blocking domain is
> used. What I am trying to say is that with the blocking domain ->
> external transition, we do not need a new UAPI for external attach for
> non-CC. It will just reuse the existing UAPI.
> VMM:
> do_ioctl(vfio_cdev_fd, VFIO_DEVICE_ATTACH_IOMMUFD_PT, &attach,
> "VFIO_DEVICE_ATTACH_IOMMUFD_PT");
> hv-iommu-root: external_domain.attach_dev() will do the hypercall.
You've basically described a wonky NESTING domain.
I think you should just use nested domains for this. Even though there
is no S2 make it possible to create a nested domain through the
viommu..
If hyperv ever learns to support VIOMMU you will need this anyhow to
pass vSTE/vDTE/etc to hyperv.
For now the nesting domain creation can just accept an empty struct or
something which means identity?
Jason
next prev parent reply other threads:[~2026-11-10 0:53 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-25 19:07 [RFC PATCH 0/9] iommu/iommufd: Add hypervisor external attach Jacob Pan
2026-09-25 19:07 ` [PATCH RFC 1/9] iommu: Introduce external attach domain type Jacob Pan
2026-10-21 10:57 ` Mostafa Saleh
2026-10-26 23:10 ` Jacob Pan
2026-11-04 10:27 ` Mostafa Saleh
2026-11-04 17:08 ` Jason Gunthorpe
2026-11-06 21:03 ` Jacob Pan
2026-11-10 0:52 ` Jason Gunthorpe [this message]
2026-09-25 19:07 ` [PATCH RFC 2/9] iommufd: Introduce hypervisor vIOMMU type Jacob Pan
2026-09-25 19:07 ` [PATCH RFC 3/9] iommufd: Add external HWPT support Jacob Pan
2026-09-25 19:07 ` [PATCH RFC 4/9] iommufd/selftest: Add hypervisor external attach backend Jacob Pan
2026-09-25 19:07 ` [PATCH RFC 5/9] mshv: Add partition file identity helper Jacob Pan
2026-09-25 19:07 ` [PATCH RFC 6/9] mshv: Add prepare callback for external device attach Jacob Pan
2026-09-25 19:07 ` [PATCH RFC 7/9] iommu/hyperv: Split root IOMMU declarations Jacob Pan
2026-09-25 19:07 ` [PATCH RFC 8/9] iommu/hyperv: Add fd-backed vIOMMU support Jacob Pan
2026-09-25 19:07 ` [PATCH RFC 9/9] iommu/hyperv: Add IOMMUFD external domains Jacob Pan
2026-10-21 10:55 ` [RFC PATCH 0/9] iommu/iommufd: Add hypervisor external attach Mostafa Saleh
2026-10-26 18:49 ` Jacob Pan
2026-11-04 10:23 ` Mostafa Saleh
2026-11-04 17:04 ` Jason Gunthorpe
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