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Date: Fri, 3 Feb 2023 10:36:30 +0100
From: Joerg Roedel <joro@8bytes.org>
To: Vasant Hegde <vasant.hegde@amd.com>
Cc: iommu@lists.linux.dev, robin.murphy@arm.com, will@kernel.org,
	suravee.suthikulpanit@amd.com, Matt Fagnani <matt.fagnani@bell.net>
Subject: Re: [PATCH 3/3] iommu/amd: Call BUG_ON in page fault hanlder path if
 domain is NULL
Message-ID: <Y9zVnkfEp3bC+UfL@8bytes.org>
References: <20230113135956.5788-1-vasant.hegde@amd.com>
 <20230113135956.5788-3-vasant.hegde@amd.com>
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In-Reply-To: <20230113135956.5788-3-vasant.hegde@amd.com>

On Fri, Jan 13, 2023 at 01:59:56PM +0000, Vasant Hegde wrote:
> If IOMMU domain for device group is not setup properly then we may hit
> IOMMU page fault. Current page fault handler assumes that domain is
> always setup and it will hit NULL pointer dereference (see below sample log).
> 
> This is mostly programming error and difficult to recover from here. Hence
> call BUG_ON().

I agree with Robin here, a BUG_ON() is no improvement over a NULL-ptr
dereference. Just handle the domain == NULL case so that this code-path
will not crash.

Thanks,

	Joerg