From: Jason Gunthorpe <jgg@ziepe.ca>
To: Mostafa Saleh <smostafa@google.com>
Cc: Jacob Pan <jacob.pan@linux.microsoft.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: [RFC PATCH 0/9] iommu/iommufd: Add hypervisor external attach
Date: Wed, 4 Nov 2026 13:04:23 -0400 [thread overview]
Message-ID: <20261104170423.GR3889730@ziepe.ca> (raw)
In-Reply-To: <ausHmkhAegDEyeKV@google.com>
On Wed, Nov 04, 2026 at 10:23:22AM +0000, Mostafa Saleh wrote:
> > IMHO, I don't see any change needed for the host-side attach between hw
> > nested and collapsed single stage, if guest and host attach are
> > split. I think it is up to pKVM or MSHV to handle guest virtual iommu
> > mapping for both cases.
>
> Although the hypervisor (pKVM, MSHV) is managing the guest IOMMU in that
> case, I believe the host should be able to decide the guest virtual
> toplology, as that will impact the firmware tables populated from the
> host for example, as in the nested case the guest will see an
> architectural SMMUv3 while in the collapsed case it will see a simple
> HVC based IOMMU.
Yes, this is how RMM/etc are working in CC land.
Untrusted hypervisor defines the vPCI topology, trusted hypervisor
implements it as instructed.
Jason
prev parent reply other threads:[~2026-11-04 17:04 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-25 19:07 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
2026-09-25 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 [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20261104170423.GR3889730@ziepe.ca \
--to=jgg@ziepe.ca \
--cc=John.Starks@microsoft.com \
--cc=alex@shazbot.org \
--cc=aneesh.kumar@kernel.org \
--cc=arnd@arndb.de \
--cc=decui@microsoft.com \
--cc=eahariha@linux.microsoft.com \
--cc=haiyangz@microsoft.com \
--cc=iommu@lists.linux.dev \
--cc=jacob.pan@linux.microsoft.com \
--cc=joro@8bytes.org \
--cc=kevin.tian@intel.com \
--cc=kys@microsoft.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-hyperv@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=longli@microsoft.com \
--cc=mukeshrathor@microsoft.com \
--cc=nicolinc@nvidia.com \
--cc=robin.murphy@arm.com \
--cc=schakrabarti@microsoft.com \
--cc=smostafa@google.com \
--cc=suravee.suthikulpanit@amd.com \
--cc=vasant.hegde@amd.com \
--cc=wei.liu@kernel.org \
--cc=will@kernel.org \
--cc=zhangyu1@linux.microsoft.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®