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From: Jason Gunthorpe <jgg@nvidia.com>
To: Will Deacon <will@kernel.org>
Cc: iommu@lists.linux.dev, Joerg Roedel <joro@8bytes.org>,
	linux-arm-kernel@lists.infradead.org,
	Robin Murphy <robin.murphy@arm.com>,
	Dan Carpenter <dan.carpenter@linaro.org>,
	Michael Shavit <mshavit@google.com>,
	Nicolin Chen <nicolinc@nvidia.com>,
	patches@lists.linux.dev
Subject: Re: [PATCH rc] iommu/arm-smmu-v3: Do not use GFP_KERNEL under as spinlock
Date: Tue, 13 Feb 2024 08:18:50 -0400	[thread overview]
Message-ID: <20240213121850.GH4048826@nvidia.com> (raw)
In-Reply-To: <20240213112015.GB28517@willie-the-truck>

On Tue, Feb 13, 2024 at 11:20:15AM +0000, Will Deacon wrote:

> Damn, all the surrounding rework has really left this poor code in a bit
> of a state. 

That's one way to describe it. There is a reason it took me so many
patches to align this to the new core APIs :(

> Could you please respin your fix, but with an additional change
> to arm_smmu_mmu_notifier_get() so that it returns an error if there is
> more than one device in the domain, with some of the above in a comment?

Adding a check is not a comprehensive solution, there are still ways
userspace can attack this code with iommufd's coming PASID support. It
certainly doesn't belong in this patch which should be backported.

I can summarize some of these details in a comment for this patch.

Jason

WARNING: multiple messages have this Message-ID (diff)
From: Jason Gunthorpe <jgg@nvidia.com>
To: Will Deacon <will@kernel.org>
Cc: iommu@lists.linux.dev, Joerg Roedel <joro@8bytes.org>,
	linux-arm-kernel@lists.infradead.org,
	Robin Murphy <robin.murphy@arm.com>,
	Dan Carpenter <dan.carpenter@linaro.org>,
	Michael Shavit <mshavit@google.com>,
	Nicolin Chen <nicolinc@nvidia.com>,
	patches@lists.linux.dev
Subject: Re: [PATCH rc] iommu/arm-smmu-v3: Do not use GFP_KERNEL under as spinlock
Date: Tue, 13 Feb 2024 08:18:50 -0400	[thread overview]
Message-ID: <20240213121850.GH4048826@nvidia.com> (raw)
In-Reply-To: <20240213112015.GB28517@willie-the-truck>

On Tue, Feb 13, 2024 at 11:20:15AM +0000, Will Deacon wrote:

> Damn, all the surrounding rework has really left this poor code in a bit
> of a state. 

That's one way to describe it. There is a reason it took me so many
patches to align this to the new core APIs :(

> Could you please respin your fix, but with an additional change
> to arm_smmu_mmu_notifier_get() so that it returns an error if there is
> more than one device in the domain, with some of the above in a comment?

Adding a check is not a comprehensive solution, there are still ways
userspace can attack this code with iommufd's coming PASID support. It
certainly doesn't belong in this patch which should be backported.

I can summarize some of these details in a comment for this patch.

Jason

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2024-02-13 12:19 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-02-02 14:28 [PATCH rc] iommu/arm-smmu-v3: Do not use GFP_KERNEL under as spinlock Jason Gunthorpe
2024-02-02 14:28 ` Jason Gunthorpe
2024-02-03  8:02 ` Michael Shavit
2024-02-03  8:02   ` Michael Shavit
2024-02-08 12:58 ` Will Deacon
2024-02-08 12:58   ` Will Deacon
2024-02-08 14:27   ` Jason Gunthorpe
2024-02-08 14:27     ` Jason Gunthorpe
2024-02-13 11:20     ` Will Deacon
2024-02-13 11:20       ` Will Deacon
2024-02-13 12:18       ` Jason Gunthorpe [this message]
2024-02-13 12:18         ` Jason Gunthorpe
2024-02-13 12:54         ` Will Deacon
2024-02-13 12:54           ` Will Deacon
2024-02-13 13:30           ` Jason Gunthorpe
2024-02-13 13:30             ` Jason Gunthorpe
2024-02-13 13:56             ` Will Deacon
2024-02-13 13:56               ` Will Deacon
2024-02-13 14:00               ` Jason Gunthorpe
2024-02-13 14:00                 ` Jason Gunthorpe
2024-02-14 17:00                 ` Will Deacon
2024-02-14 17:00                   ` Will Deacon
2024-02-14 19:09                   ` Jason Gunthorpe
2024-02-14 19:09                     ` Jason Gunthorpe
2024-02-15 11:38                     ` Will Deacon
2024-02-15 11:38                       ` Will Deacon

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