Re: [PATCH 1/2] iommu/amd: Fix illegal device-id access in IOMMU debugfs

[Vasant Hegde <vasant.hegde@amd.com>]

On 3/19/2026 1:07 PM, Guanghui Feng wrote:
> In the current AMD IOMMU debugFS, when multiple processes use the IOMMU
> debugFS process simultaneously, illegal access issues can occur in the
> following execution flow:
> 
> 1. CPU1: Sets a valid sbdf via devid_write, then checks the sbdf's
> validity in execution flows such as devid_show, iommu_devtbl_show,
> and iommu_irqtbl_show.
> 
> 2. CPU2: Sets an invalid sbdf via devid_write, at which point the sbdf
> value is -1.
> 
> 3. CPU1: accesses the IOMMU device table, IRQ table, based on the
> invalid SBDF value of -1, resulting in illegal access.
> 
> This is especially problematic in monitoring scripts, where multiple
> scripts may access debugFS simultaneously, and some scripts may
> unexpectedly set invalid values, which triggers illegal access in
> debugfs.
> 
> This patch modifies the execution flow of devid_show,
> iommu_devtbl_show, and iommu_irqtbl_show to ensure that these
> processes determine the validity and access based on the
> same device-id, thus guaranteeing correctness and robustness.
> 
 Signed-off-by: Guanghui Feng <guanghuifeng@linux.alibaba.com>

Looks good.

Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>

-Vasant