From: Jason Gunthorpe <jgg@nvidia.com>
To: Dmitry Malkin <dma@nebius.com>
Cc: Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
Joerg Roedel <joro@8bytes.org>,
Nicolin Chen <nicolinc@nvidia.com>,
"iommu@lists.linux.dev" <iommu@lists.linux.dev>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"regressions@lists.linux.dev" <regressions@lists.linux.dev>,
"stable@vger.kernel.org" <stable@vger.kernel.org>,
NB-Core Team <NB-CoreTeam@nebius.com>
Subject: Re: [RFC PATCH] iommu/arm-smmu-v3: Allow nested attach for PCI bridges without vDEVICE
Date: Fri, 14 Aug 2026 19:11:03 -0300 [thread overview]
Message-ID: <20260814221103.GE510472@nvidia.com> (raw)
In-Reply-To: <PA1P190MB25573D7CFE42EF7DD2A8CDE8DBDA2@PA1P190MB2557.EURP190.PROD.OUTLOOK.COM>
On Fri, Aug 14, 2026 at 06:56:05PM +0000, Dmitry Malkin wrote:
> Hi Jason,
>
> > If viommu should support multi-device groups, I'm not sure. I want to
> > know why you even have multi-device groups in the first place because
> > that is not normal at all.
>
> That is because of the 'pci=config_acs' kernel command-line
> parameter. This causes the kernel to create a single IOMMU group
> containing multiple PCIe devices, including the bridge (PCIe Root
> Port).
Don't use it that way?
If this is an nvidia system you should talk to your support team.
Jason
prev parent reply other threads:[~2026-08-14 22:11 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-14 10:07 [RFC PATCH] iommu/arm-smmu-v3: Allow nested attach for PCI bridges without vDEVICE Dmitry Malkin
2026-08-14 14:15 ` Pranjal Shrivastava
2026-08-14 15:40 ` Dmitry Malkin
2026-08-14 17:49 ` Jason Gunthorpe
2026-08-14 17:48 ` Jason Gunthorpe
2026-08-14 18:56 ` Dmitry Malkin
2026-08-14 22:11 ` Jason Gunthorpe [this message]
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