linux-kernel - Re: [PATCH] iommu: amd: Fix uninitialized dev

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Message-ID: <561ab88a-ba97-41d8-ad6a-8656a2e2b1d5@amd.com>
Date: Mon, 12 Jan 2026 10:42:35 +0530
From: Vasant Hegde <vasant.hegde@....com>
To: Jörg Rödel <joro@...tes.org>,
 Rakuram Eswaran <rakuram.e96@...il.com>
Cc: will@...nel.org, suravee.suthikulpanit@....com, robin.murphy@....com,
 dan.carpenter@...aro.org, iommu@...ts.linux.dev, lkp@...el.com,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iommu: amd: Fix uninitialized dev_data on probe failure

On 1/10/2026 3:39 PM, JÃ¶rg RÃ¶del wrote:
> On Sun, Dec 21, 2025 at 11:04:16PM +0530, Rakuram Eswaran wrote:
>> diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
>> index 5d45795c367a..075125f0f52b 100644
>> --- a/drivers/iommu/amd/iommu.c
>> +++ b/drivers/iommu/amd/iommu.c
>> @@ -2426,7 +2426,7 @@ static struct iommu_device *amd_iommu_probe_device(struct device *dev)
>>  		dev_err(dev, "Failed to initialize - trying to proceed anyway\n");
>>  		iommu_dev = ERR_PTR(ret);
>>  		iommu_ignore_device(iommu, dev);
>> -		goto out_err;
>> +		return iommu_dev;
>>  	}
> 
> This is not the right fix. It makes the function omit further initialization
> steps which are needed event when iommu_init_device() fails (which it only does
> on out-of-memory).
> 
> The right fix is to initialize dev_data to NULL and check for that value before
> dereferencing it further down to keep the current logic.

Ack. I think this function needs rewrite. PCIe device capability
check/enablement is scattered between this one and iommu_init_device(). I will
fix it as part of other PASID related fixes/cleanups.

I think for now below fix is good enough.

@Rakuram, @Joerg, let me know if you want me to send proper patch?


Fixes: 19e5cc156c ("iommu/amd: Enable support for up to 2K interrupts per function")

---
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index e46a63c85337..87bba1d31a6c 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -2983,8 +2983,6 @@ static struct iommu_device *amd_iommu_probe_device(struct
device *dev)
 		goto out_err;
 	}

-out_err:
-
 	iommu_completion_wait(iommu);

 	if (FEATURE_NUM_INT_REMAP_SUP_2K(amd_iommu_efr2))
@@ -2995,6 +2993,7 @@ static struct iommu_device *amd_iommu_probe_device(struct
device *dev)
 	if (dev_is_pci(dev))
 		pci_prepare_ats(to_pci_dev(dev), PAGE_SHIFT);

+out_err:
 	return iommu_dev;
 }



-Vasant