From: Jason Gunthorpe <jgg@ziepe.ca>
To: Mostafa Saleh <smostafa@google.com>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev,
iommu@lists.linux.dev, catalin.marinas@arm.com, will@kernel.org,
maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com,
suzuki.poulose@arm.com, yuzenghui@huawei.com, joro@8bytes.org,
jean-philippe@linaro.org, mark.rutland@arm.com,
qperret@google.com, tabba@google.com, vdonnefort@google.com,
sebastianene@google.com, keirf@google.com
Subject: Re: [PATCH v6 08/25] KVM: arm64: iommu: Shadow host stage-2 page table
Date: Fri, 1 May 2026 10:00:06 -0300 [thread overview]
Message-ID: <20260501130006.GF6912@ziepe.ca> (raw)
In-Reply-To: <20260501111928.259252-9-smostafa@google.com>
On Fri, May 01, 2026 at 11:19:10AM +0000, Mostafa Saleh wrote:
> Create a page-table for the IOMMU that shadows the host CPU stage-2
> to establish DMA isolation.
Is there a reason you can't just use the CPU S2 for the iommu?
ie the CCA RMM is doing that, it is how ARM imagined this stuff would
work.
Once you start supporting DMA like this you have no choice but to keep
a fully populated at all times S2 around, why not use that for the CPU
too to avoid faults?
I guess there is a reason, but maybe explain in the commit message?
It sure would be simpler, you wouldn't have to mess with iopgtable at
all...
Jason
next prev parent reply other threads:[~2026-05-01 13:00 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-01 11:19 [PATCH v6 00/25] KVM: arm64: SMMUv3 driver for pKVM (trap and emulate) Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 01/25] KVM: arm64: Generalize trace clock Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 02/25] KVM: arm64: Donate MMIO to the hypervisor Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 03/25] iommu/arm-smmu-v3: Split code with hyp Mostafa Saleh
2026-05-01 12:44 ` Jason Gunthorpe
2026-05-04 12:13 ` Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 04/25] iommu/arm-smmu-v3: Move TLB range invalidation into common code Mostafa Saleh
2026-05-01 12:41 ` Jason Gunthorpe
2026-05-04 12:15 ` Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 05/25] iommu/arm-smmu-v3: Move IDR parsing to common functions Mostafa Saleh
2026-05-01 12:47 ` Jason Gunthorpe
2026-05-04 12:16 ` Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 06/25] iommu/io-pgtable-arm: Rework to use the iommu-pages API Mostafa Saleh
2026-05-01 12:24 ` Jason Gunthorpe
2026-05-04 12:19 ` Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 07/25] KVM: arm64: iommu: Introduce IOMMU driver infrastructure Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 08/25] KVM: arm64: iommu: Shadow host stage-2 page table Mostafa Saleh
2026-05-01 13:00 ` Jason Gunthorpe [this message]
2026-05-04 12:28 ` Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 09/25] KVM: arm64: iommu: Add memory pool Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 10/25] KVM: arm64: iommu: Support DABT for IOMMU Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 11/25] iommu/arm-smmu-v3-kvm: Add SMMUv3 driver Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 12/25] iommu/arm-smmu-v3-kvm: Add the kernel driver Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 13/25] iommu/arm-smmu-v3-kvm: Probe SMMU HW Mostafa Saleh
2026-05-01 12:51 ` Jason Gunthorpe
2026-05-04 12:30 ` Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 14/25] iommu/arm-smmu-v3-kvm: Add MMIO emulation Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 15/25] iommu/arm-smmu-v3-kvm: Shadow the command queue Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 16/25] iommu/arm-smmu-v3-kvm: Add CMDQ functions Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 17/25] iommu/arm-smmu-v3-kvm: Emulate CMDQ for host Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 18/25] iommu/arm-smmu-v3-kvm: Shadow stream table Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 19/25] iommu/arm-smmu-v3-kvm: Shadow STEs Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 20/25] iommu/arm-smmu-v3-kvm: Share other queues Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 21/25] iommu/arm-smmu-v3-kvm: Emulate GBPA Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 22/25] iommu/io-pgtable-arm: Support io-pgtable-arm in the hypervisor Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 23/25] iommu/arm-smmu-v3-kvm: Shadow the CPU stage-2 page table Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 24/25] iommu/arm-smmu-v3-kvm: Enable nesting Mostafa Saleh
2026-05-01 11:19 ` [PATCH v6 25/25] KVM: arm64: Add documentation for pKVM DMA isolation Mostafa Saleh
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