From: "Michael S. Tsirkin" <mst@redhat.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: "Demi Marie Obenour" <demiobenour@gmail.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: Tue, 17 Jun 2025 15:44:20 -0400 [thread overview]
Message-ID: <20250617154331-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20250616132031.GB1354058@ziepe.ca>
On Mon, Jun 16, 2025 at 10:20:31AM -0300, Jason Gunthorpe wrote:
> On Sun, Jun 15, 2025 at 02:47:15PM -0400, Demi Marie Obenour wrote:
>
> > Is a paravirtualized IOMMU with interrupt remapping something that makes
> > sense?
>
> IMHO linking interrupt remapping to the iommu is a poor design,
> interrupt routing belongs in the irq subsystem, not in the iommu.
>
> The fact AMD and Intel both coupled their interrupt routing to their
> iommu hardware is just a weird design decision. ARM didn't do this,
> for instance.
why does it matter in which device it resides?
Way I see it, there is little reason to remap interrupts
without also using an iommu, so why not a single device.
what did I miss?
> So I would not try to do this at all, you should have a
> para-virtualized IRQ interface, not an extension to virtio-iommu
> adding interrupt handling. :\
>
> AFAIK hyperv shows how to build something like this.
>
> Jason
next prev parent reply other threads:[~2025-06-17 19:44 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
2025-06-17 19:44 ` Michael S. Tsirkin [this message]
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
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