From: Jason Gunthorpe <jgg@nvidia.com>
To: Steven Price <steven.price@arm.com>
Cc: Boris Brezillon <boris.brezillon@collabora.com>,
iommu@lists.linux.dev, Joerg Roedel <joro@8bytes.org>,
linux-arm-kernel@lists.infradead.org,
Robin Murphy <robin.murphy@arm.com>,
Will Deacon <will@kernel.org>,
dri-devel@lists.freedesktop.org,
Liviu Dudau <liviu.dudau@arm.com>,
patches@lists.linux.dev
Subject: Re: [PATCH] iommu/io-pgtable-arm: Remove split on unmap behavior
Date: Mon, 21 Oct 2024 09:17:24 -0300 [thread overview]
Message-ID: <20241021121724.GN3559746@nvidia.com> (raw)
In-Reply-To: <850c70ff-a7f0-4a0b-83a4-0b03a039831d@arm.com>
On Mon, Oct 21, 2024 at 12:32:21PM +0100, Steven Price wrote:
> > that, we can always do it in two steps (unmap the 2M region and remap
> > the borders). At some point it'd be good to have some kind of atomic
> > page table updates, so we don't have this short period of time during
> > which nothing is mapped (between the unmap and the remap), but that's a
> > different story.
>
> The GPU hardware provides that. The only possible missing piece is that
> the driver needs to know ahead of time that the unmap would unmap the 2M
> region so it can do the correct lock before the entries are removed.
It looks like we need atomic update for some confidential compute
scenarios, so I am working toward that with the coming generic pt
stuff.
> >> If DRM does use this, I'd respin this to make it into a quirk and iommu won't
> >> set it.
>
> You should be safe as far as Panfrost and Panthor are concerned.
Great, thanks!
Jason
next prev parent reply other threads:[~2024-10-21 12:25 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-18 17:19 [PATCH] iommu/io-pgtable-arm: Remove split on unmap behavior Jason Gunthorpe
2024-10-21 9:17 ` Boris Brezillon
2024-10-21 11:32 ` Steven Price
2024-10-21 12:17 ` Jason Gunthorpe [this message]
2024-10-21 13:50 ` Robin Murphy
2024-10-21 14:20 ` Jason Gunthorpe
2024-10-24 13:05 ` Will Deacon
2024-10-24 13:44 ` Jason Gunthorpe
2024-11-01 11:54 ` Will Deacon
2024-11-01 11:58 ` Will Deacon
2024-11-01 15:37 ` Jason Gunthorpe
2024-11-01 13:40 ` Jason Gunthorpe
2024-11-04 11:32 ` Will Deacon
2025-07-05 20:12 ` Daniel Mentz
2025-07-07 16:05 ` Liviu Dudau
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