From: Mostafa Saleh <smostafa@google•com>
To: Jason Gunthorpe <jgg@ziepe•ca>
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 04/25] iommu/arm-smmu-v3: Move TLB range invalidation into common code
Date: Thu, 7 May 2026 09:40:00 +0000 [thread overview]
Message-ID: <afxd8Km40A5ulZvd@google.com> (raw)
In-Reply-To: <afsPfEzgGtAFrN5P@ziepe.ca>
On Wed, May 06, 2026 at 06:53:00AM -0300, Jason Gunthorpe wrote:
> On Tue, May 05, 2026 at 04:43:13PM +0000, Mostafa Saleh wrote:
> > On Tue, May 05, 2026 at 01:17:09PM -0300, Jason Gunthorpe wrote:
> > > On Mon, May 04, 2026 at 12:15:17PM +0000, Mostafa Saleh wrote:
> > >
> > > > I am not sure if it’s worth it, the hypervisor is much simpler, there
> > > > is a single page table, it’s locked (also identity mapped), it’s
> > > > updated on VM boot/teardown only, we don’t even use iotlb_gather at
> > > > the moment, although possible but I wanted to keep this series as
> > > > simple as I can then we can add more features later.
> > > > So this patch is the least intrusive change, as whatever the main SMMUv3
> > > > driver does, the range tlb invalidation logic is the same.
> > > > But I am happy to experiment with that when posted.
> > >
> > > Okay, then maybe just always push a full invalidation?
> >
> > Like full address space invalidation? that will not be optimal and
> > will affect every device on the system, why would we do that if we
> > know the address?
>
> Not every device, just wipe the VMID. If you say it is rare then keep
> it simple. If you need to be narrow then use the proper infastructure
> with a gather. No reason to make something boutique for pkvm here.
But all devices share the same VMID, which impacts all devices on the
system, and is not that rare to ignore.
I can add gather support, it’s not that complicated, it is currently
supported in Android.
But that doesn’t solve the problem, which is: At some point, whether
eagerly from the page table code, through gather sync or a fancy
invalidation array, the driver will need to populate a range
invalidation command (tg, ttl, scale...) and this logic is better
shared with the main driver which is this patch does.
Thanks,
Mostafa
>
> Jason
next prev parent reply other threads:[~2026-05-07 9:40 UTC|newest]
Thread overview: 61+ 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
2026-05-05 16:17 ` Jason Gunthorpe
2026-05-05 16:43 ` Mostafa Saleh
2026-05-06 9:53 ` Jason Gunthorpe
2026-05-07 9:40 ` Mostafa Saleh [this message]
2026-05-09 23:29 ` Jason Gunthorpe
2026-05-11 11:45 ` Mostafa Saleh
2026-05-11 14:24 ` Jason Gunthorpe
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
2026-05-05 16:27 ` Jason Gunthorpe
2026-05-05 16:48 ` Mostafa Saleh
2026-05-06 9:56 ` Jason Gunthorpe
2026-05-07 10:13 ` Mostafa Saleh
2026-05-09 23:34 ` Jason Gunthorpe
2026-05-11 11:53 ` Mostafa Saleh
2026-05-11 14:30 ` Jason Gunthorpe
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
2026-05-09 23:21 ` Jason Gunthorpe
2026-05-11 11:16 ` Mostafa Saleh
2026-05-11 14:18 ` Jason Gunthorpe
2026-05-13 21:54 ` 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
2026-05-04 12:28 ` Mostafa Saleh
2026-05-09 23:27 ` Jason Gunthorpe
2026-05-11 11:24 ` Mostafa Saleh
2026-05-11 14:22 ` Jason Gunthorpe
2026-05-12 10:42 ` Mostafa Saleh
2026-05-12 12:36 ` Jason Gunthorpe
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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