From: Jason Gunthorpe <jgg@ziepe.ca>
To: Will Deacon <will@kernel.org>
Cc: Robin Murphy <robin.murphy@arm.com>,
nicolinc@nvidia.com, joro@8bytes.org, jpb@kernel.org,
catalin.marinas@arm.com, yangyicong@hisilicon.com,
linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev,
stable@vger.kernel.org
Subject: Re: [PATCH] iommu/arm-smmu-v3: Add HAFT support for SVA
Date: Fri, 24 Jul 2026 12:25:40 -0300 [thread overview]
Message-ID: <amOD9GAz0j7wMMij@ziepe.ca> (raw)
In-Reply-To: <amFCQDrEowvL28O_@willie-the-truck>
On Wed, Jul 22, 2026 at 11:20:48PM +0100, Will Deacon wrote:
> > We might block traffic in the process of _explicitly blocking traffic_!?
> > Whoop-de-do, surely?
>
> Hmm. I have very vague memories that there were some virtualisation (?)
> cases where Jason and Nicolin cared about the type of event that would
> be generated by concurrent DMA (e.g. bad CD vs translation fault) but
> maybe I'm misremembering.
Yeah, it is actually important for that special SVA mm drop/release
case. We need to write a CD that blocks walking but always generates
translation fault.
I'm away from my computer right now, but if sashiko is saying that the
SVA flow that uses EPD generates a racy bad CD then that is a bug that
needs to be fixed. Possibly by ignoring HAFT in the used calculation
for the EPD cases.
We should also try to have a kunit to cover that specific mm drop flow
in the SVA code.
Jason
next prev parent reply other threads:[~2026-07-24 15:25 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-01 17:45 [PATCH] iommu/arm-smmu-v3: Add HAFT support for SVA Robin Murphy
2026-07-03 16:49 ` Jason Gunthorpe
2026-07-03 18:57 ` Robin Murphy
2026-07-03 19:24 ` Jason Gunthorpe
2026-07-06 14:13 ` Robin Murphy
2026-07-09 16:04 ` Jason Gunthorpe
2026-07-09 16:44 ` Robin Murphy
2026-07-22 13:24 ` Will Deacon
2026-07-22 16:56 ` Robin Murphy
2026-07-22 22:20 ` Will Deacon
2026-07-24 15:25 ` Jason Gunthorpe [this message]
2026-07-24 16:42 ` Robin Murphy
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