From: Jason Gunthorpe <jgg@nvidia.com>
To: Andrew Jones <andrew.jones@oss.qualcomm.com>
Cc: linux-riscv@lists.infradead.org, iommu@lists.linux.dev,
linux-kernel@vger.kernel.org, tomasz.jeznach@linux.dev,
tjeznach@rivosinc.com, joro@8bytes.org, will@kernel.org,
robin.murphy@arm.com, pjw@kernel.org, palmer@dabbelt.com,
anup@brainfault.org, tglx@kernel.org, kevin.tian@intel.com,
fangyu.yu@linux.alibaba.com
Subject: Re: [PATCH v4 02/21] iommufd: Add iommufd_sw_map_msi()
Date: Fri, 21 Aug 2026 11:31:55 -0300 [thread overview]
Message-ID: <20260821143155.GI244917@nvidia.com> (raw)
In-Reply-To: <yikhefui2flgfffmtbpdxemjtto2ryfmkgtlgdtmr2ndgxrw3r@rcjz523m3sw5>
On Fri, Aug 21, 2026 at 04:23:22PM +0200, Andrew Jones wrote:
> > But RISC-V IOMMU is also not involved in interrupt translation. Beyond
> > it could remap the PAs which represent the CPUs, but you are not using
> > it that way since it is statically setup.
> >
> > So I'm not sure why the iommu gets an IR? Isn't it the same as ARM
> > where the IMSIC itself just has a wack of PAs it needs to access so it
> > calls iommu_dma_prepare_msi() to do it?
>
> Right, this series is only remapping IMSIC PAs, not using the IOMMU MSI
> table. The MSI table must be disabled when second-stage translation is
> Bare, so it cannot be used for the host mappings here. It will be needed
> for guest interrupt files (the irqbypass series I'm also working on),
> where this IR irqdomain can then intercept irq_set_vcpu_affinity().
> Also, keeping the MSI setup in this IR irqdomain avoids putting IOMMU
> mapping knowledge in the IMSIC driver.
It's ok for the IMSIC driver to call iommu_dma_prepare_msi(), that's
the architecutre of this at least.
Until you get to adding something more complicated, eg irqbypass, I'd
suggest keeping this series simple.
I guess I would wonder why the IOMMU needs to be involved in changing
the mapping down the road, why not just reprogram the MSI-X address?
Jason
next prev parent reply other threads:[~2026-08-21 14:32 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-20 21:41 [PATCH v4 00/21] iommu/riscv: Enable MSI remapping, IOMMU_DMA and VFIO Andrew Jones
2026-08-20 21:41 ` [PATCH v4 01/21] iommufd: Convert struct iommufd_sw_msi_maps to a growable bitmap Andrew Jones
2026-08-20 21:41 ` [PATCH v4 02/21] iommufd: Add iommufd_sw_map_msi() Andrew Jones
2026-08-20 22:09 ` Jason Gunthorpe
2026-08-21 11:07 ` Andrew Jones
2026-08-21 12:02 ` Jason Gunthorpe
2026-08-21 13:47 ` Andrew Jones
2026-08-21 14:00 ` Jason Gunthorpe
2026-08-21 14:23 ` Andrew Jones
2026-08-21 14:31 ` Jason Gunthorpe [this message]
2026-08-21 15:18 ` Andrew Jones
2026-08-21 16:12 ` Jason Gunthorpe
2026-08-21 17:12 ` Andrew Jones
2026-08-21 17:20 ` Jason Gunthorpe
2026-08-20 21:41 ` [PATCH v4 03/21] iommu/dma: Add iommu_dma_sw_map_msi() Andrew Jones
2026-08-20 21:41 ` [PATCH v4 04/21] iommu/dma: Add iommu_dma_map_msi() Andrew Jones
2026-08-20 21:41 ` [PATCH v4 05/21] iommu: Document MSI mapping during domain replacement Andrew Jones
2026-08-20 21:41 ` [PATCH v4 06/21] genirq/msi: Provide DOMAIN_BUS_MSI_REMAP Andrew Jones
2026-08-20 21:41 ` [PATCH v4 07/21] irqchip/riscv-imsic: Compose MSI updates through the hierarchy Andrew Jones
2026-08-20 21:41 ` [PATCH v4 08/21] iommu/riscv: Add IRQ domain for interrupt remapping Andrew Jones
2026-08-20 21:41 ` [PATCH v4 09/21] iommu/riscv: Refresh platform MSI domain before IR setup Andrew Jones
2026-08-20 21:41 ` [PATCH v4 10/21] iommu/riscv: Prepare info->domain for concurrent RCU read access Andrew Jones
2026-08-20 21:41 ` [PATCH v4 11/21] iommu/riscv: Reserve an MSI IOVA window for iommufd Andrew Jones
2026-08-20 21:41 ` [PATCH v4 12/21] iommu/riscv: Pre-map IMSIC MSI targets Andrew Jones
2026-08-20 21:41 ` [PATCH v4 13/21] iommu/riscv: Preserve MSI IOVA state across domain replacement Andrew Jones
2026-08-20 21:52 ` Jason Gunthorpe
2026-08-21 11:14 ` Andrew Jones
2026-08-21 13:22 ` Jason Gunthorpe
2026-08-21 13:56 ` Andrew Jones
2026-08-20 21:41 ` [PATCH v4 14/21] iommu/riscv: Gate direct identity boundary switches with live MSIs Andrew Jones
2026-08-20 21:41 ` [PATCH v4 15/21] iommu/riscv: Remap IMSIC targets during MSI composition Andrew Jones
2026-08-20 21:41 ` [PATCH v4 16/21] iommu/dma: Enable IOMMU_DMA for 64-bit RISC-V Andrew Jones
2026-08-20 21:41 ` [PATCH v4 17/21] iommu/riscv: Report cache coherency capability Andrew Jones
2026-08-20 21:47 ` Jason Gunthorpe
2026-08-21 11:15 ` Andrew Jones
2026-08-20 21:41 ` [PATCH v4 18/21] vfio: enable IOMMU_TYPE1 for RISC-V Andrew Jones
2026-08-20 21:41 ` [PATCH v4 19/21] RISC-V: KVM: Enable KVM_VFIO interfaces on RISC-V arch Andrew Jones
2026-08-20 21:41 ` [PATCH v4 20/21] riscv: defconfig: Enable IOMMUFD and VFIO Andrew Jones
2026-08-20 21:41 ` [PATCH v4 21/21] selftests/vfio: Allow building on RISC-V Andrew Jones
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=20260821143155.GI244917@nvidia.com \
--to=jgg@nvidia.com \
--cc=andrew.jones@oss.qualcomm.com \
--cc=anup@brainfault.org \
--cc=fangyu.yu@linux.alibaba.com \
--cc=iommu@lists.linux.dev \
--cc=joro@8bytes.org \
--cc=kevin.tian@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=palmer@dabbelt.com \
--cc=pjw@kernel.org \
--cc=robin.murphy@arm.com \
--cc=tglx@kernel.org \
--cc=tjeznach@rivosinc.com \
--cc=tomasz.jeznach@linux.dev \
--cc=will@kernel.org \
/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