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 17/21] iommu/riscv: Report cache coherency capability
Date: Thu, 20 Aug 2026 18:47:30 -0300 [thread overview]
Message-ID: <20260820214730.GC244917@nvidia.com> (raw)
In-Reply-To: <20260820214150.545737-18-andrew.jones@oss.qualcomm.com>
On Thu, Aug 20, 2026 at 11:41:46PM +0200, Andrew Jones wrote:
> VFIO and iommufd require IOMMU_CAP_CACHE_COHERENCY because they use
> IOMMU_CACHE mappings and have no userspace cache-maintenance path.
>
> RISC-V page tables preserve physical memory attributes for IOMMU_CACHE
> mappings. Svpbmt marks mappings without IOMMU_CACHE as non-cacheable,
> but preserving physical attributes cannot make a noncoherent device
> path coherent.
>
> Report the capability only for devices marked DMA coherent. This limits
> userspace assignment to paths that can honor cacheable mappings.
>
> Signed-off-by: Andrew Jones <andrew.jones@oss.qualcomm.com>
> ---
> drivers/iommu/riscv/iommu.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
You can send this outside this series?
Jason
next prev parent reply other threads:[~2026-08-20 21:47 UTC|newest]
Thread overview: 25+ 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
2026-08-20 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
2026-08-20 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 [this message]
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
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