From: Jean-Philippe Brucker <jean-philippe@linaro.org>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jacob Pan <jacob.pan@linux.microsoft.com>,
iommu@lists.linux.dev, Joerg Roedel <joro@8bytes.org>,
Robin Murphy <robin.murphy@arm.com>,
virtualization@lists.linux.dev, Will Deacon <will@kernel.org>,
Eric Auger <eric.auger@redhat.com>,
patches@lists.linux.dev
Subject: Re: [PATCH 0/5] Convert virtio-iommu to domain_alloc_paging()
Date: Fri, 21 Feb 2025 11:42:06 +0000 [thread overview]
Message-ID: <20250221114206.GB719702@myrica> (raw)
In-Reply-To: <20250212125007.GP3754072@nvidia.com>
On Wed, Feb 12, 2025 at 08:50:07AM -0400, Jason Gunthorpe wrote:
> On Tue, Feb 11, 2025 at 04:41:51PM -0800, Jacob Pan wrote:
>
> > I see the same on arm64 with v9.0, assigned an ixgbe nic via VFIO.
>
> Huh, I figured it worked on ARM..
Crosvm would be a more useful test because it doesn't implement any BYPASS
feature, but I don't have it set up at the moment. It's not a problem on
QEMU since it supports the BYPASS feature and doesn't need identity-mapped
domains.
>
> There is no requirement that an iommu driver implement identity, this
> is all an optimization. If it doesn't work in alot of cases can we
> just remove it? It would simplfy a lot..
No objection. Identity domains are useful if the use-case of virtio-iommu
is assigning devices to guest userspace, in which case you'd want to
bypass the IOMMU for the devices that are still owned by the kernel. But
VMMs have at least two alternatives to identity-mapping (BYPASS feature
and tailored topology).
Thanks,
Jean
next prev parent reply other threads:[~2025-02-21 11:41 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-07 14:46 [PATCH 0/5] Convert virtio-iommu to domain_alloc_paging() Jason Gunthorpe
2025-02-07 14:46 ` [PATCH 1/5] iommu/virtio: Break out bypass identity support into a global static Jason Gunthorpe
2025-02-12 0:43 ` Jacob Pan
2025-02-18 18:21 ` Jason Gunthorpe
2025-02-21 11:35 ` Jean-Philippe Brucker
2025-02-24 19:37 ` Jason Gunthorpe
2025-02-07 14:46 ` [PATCH 2/5] iommu: Add domain_alloc_identity() Jason Gunthorpe
2025-02-12 13:56 ` Robin Murphy
2025-02-12 14:03 ` Jason Gunthorpe
2025-02-12 14:16 ` Robin Murphy
2025-02-12 14:45 ` Jason Gunthorpe
2025-02-07 14:46 ` [PATCH 3/5] iommu/virtio: Move to domain_alloc_paging() Jason Gunthorpe
2025-02-12 19:22 ` Jacob Pan
2025-02-12 23:30 ` Jason Gunthorpe
2025-02-13 5:47 ` Jacob Pan
2025-02-18 20:01 ` Jason Gunthorpe
[not found] ` <67ad876d.170a0220.3c21dc.85ceSMTPIN_ADDED_BROKEN@mx.google.com>
2025-02-13 9:46 ` Jean-Philippe Brucker
2025-02-13 17:03 ` Yu Zhang
2025-02-13 18:09 ` Jean-Philippe Brucker
2025-02-19 9:39 ` Yu Zhang
2025-02-19 10:35 ` Jean-Philippe Brucker
2025-02-19 11:11 ` Yu Zhang
2025-02-19 11:57 ` Jean-Philippe Brucker
2025-02-19 13:10 ` Yi Liu
2025-02-20 2:58 ` Baolu Lu
2025-02-20 3:44 ` Yu Zhang
2025-02-07 14:46 ` [PATCH 4/5] iommu: Do not call domain_alloc() in iommu_sva_domain_alloc() Jason Gunthorpe
2025-02-07 14:46 ` [PATCH 5/5] iommu: Hide ops.domain_alloc behind CONFIG_FSL_PAMU Jason Gunthorpe
2025-02-12 0:41 ` [PATCH 0/5] Convert virtio-iommu to domain_alloc_paging() Jacob Pan
2025-02-12 12:50 ` Jason Gunthorpe
2025-02-12 18:50 ` Jacob Pan
2025-02-12 20:10 ` Robin Murphy
2025-02-21 11:42 ` Jean-Philippe Brucker [this message]
2025-02-24 19:39 ` Jason Gunthorpe
[not found] ` <67abee53.170a0220.154671.ae28SMTPIN_ADDED_BROKEN@mx.google.com>
2025-02-12 11:58 ` Jean-Philippe Brucker
2025-02-12 17:05 ` Jacob Pan
[not found] ` <67acd4e2.630a0220.365aab.e098SMTPIN_ADDED_BROKEN@mx.google.com>
2025-02-12 19:16 ` Jean-Philippe Brucker
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