From: Jason Gunthorpe <jgg@ziepe.ca>
To: Demi Marie Obenour <demiobenour@gmail.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
"Jason Wang" <jasowang@redhat.com>,
"Xuan Zhuo" <xuanzhuo@linux.alibaba.com>,
"Eugenio Pérez" <eperezma@redhat.com>,
"Rafael J. Wysocki" <rafael@kernel.org>,
"Len Brown" <lenb@kernel.org>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Ingo Molnar" <mingo@redhat.com>,
"Borislav Petkov" <bp@alien8.de>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
"Joerg Roedel" <joro@8bytes.org>, "Will Deacon" <will@kernel.org>,
"Robin Murphy" <robin.murphy@arm.com>,
"Alyssa Ross" <hi@alyssa.is>,
virtualization@lists.linux.dev, linux-kernel@vger.kernel.org,
linux-acpi@vger.kernel.org, iommu@lists.linux.dev,
x86@kernel.org, "Spectrum OS Development" <devel@spectrum-os.org>
Subject: Re: Virtio-IOMMU interrupt remapping design
Date: Mon, 16 Jun 2025 14:33:05 -0300 [thread overview]
Message-ID: <20250616173305.GA1376249@ziepe.ca> (raw)
In-Reply-To: <8c3b08d5-24aa-4db2-84e1-dfd1d2c52065@gmail.com>
On Mon, Jun 16, 2025 at 12:53:40PM -0400, Demi Marie Obenour wrote:
> > AFAIK hyperv shows how to build something like this.
> Would this need KVM patches? I'm concerned that implementing this
> in userspace would interact badly with the irqfd fast path.
I don't know. I think you get the same issues even if you did
virtio-iommu irq handling, it shouldn't be any different.
I'm not sure there even is a fast path here, remapping happens during
initial vector setup/affinity change only. That isn't fast path. So
long as the MSI is delivered to the correct CPU vector entirely in KVM
it seems OK.
And the hyperv approach of asking the hypervisor for the addr/data
pair to achieve certain parameters will work alot better with existing
Linux than trying to build a iommu emulation where the guest is
building its own private addr/data pairs :\
Jason
next prev parent reply other threads:[~2025-06-16 17:33 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-15 18:47 Virtio-IOMMU interrupt remapping design Demi Marie Obenour
2025-06-16 13:20 ` Jason Gunthorpe
2025-06-16 16:53 ` Demi Marie Obenour
2025-06-16 17:33 ` Jason Gunthorpe [this message]
2025-06-17 19:44 ` Michael S. Tsirkin
2025-06-17 19:57 ` Jason Gunthorpe
2025-06-17 20:01 ` Michael S. Tsirkin
2025-06-17 23:03 ` Jason Gunthorpe
2025-06-17 19:46 ` Michael S. Tsirkin
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=20250616173305.GA1376249@ziepe.ca \
--to=jgg@ziepe.ca \
--cc=bp@alien8.de \
--cc=dave.hansen@linux.intel.com \
--cc=demiobenour@gmail.com \
--cc=devel@spectrum-os.org \
--cc=eperezma@redhat.com \
--cc=hi@alyssa.is \
--cc=hpa@zytor.com \
--cc=iommu@lists.linux.dev \
--cc=jasowang@redhat.com \
--cc=joro@8bytes.org \
--cc=lenb@kernel.org \
--cc=linux-acpi@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=mst@redhat.com \
--cc=rafael@kernel.org \
--cc=robin.murphy@arm.com \
--cc=tglx@linutronix.de \
--cc=virtualization@lists.linux.dev \
--cc=will@kernel.org \
--cc=x86@kernel.org \
--cc=xuanzhuo@linux.alibaba.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