Re: [PATCH] iommu/arm-smmu-v3: Fix iommu_device_probe bug due to duplicated stream ids

[Jason Gunthorpe]

On Sat, Apr 12, 2025 at 11:06:58AM -0700, Nicolin Chen wrote:
> ASPEED VGA card has two built-in devices:
>  0008:06:00.0 PCI bridge: ASPEED Technology, Inc. AST1150 PCI-to-PCI Bridge (rev 06)
>  0008:07:00.0 VGA compatible controller: ASPEED Technology, Inc. ASPEED Graphics Family (rev 52)
> 
> Since SMMU driver had been already expecting a potential duplicated Stream
> ID in arm_smmu_install_ste_for_dev(), change the arm_smmu_insert_master()
> routine to ignore a duplicated ID from the fwspec->sids array as well.
> 
> Note: this has been failing the iommu_device_probe() since 2021, although a
> recent iommu commit in v6.15-rc1 that moves iommu_device_probe() started to
> fail the SMMU driver probe. Since nobody has cared about DMA Alias support,
> leave that as it was but fix the fundamental iommu_device_probe() breakage.
> 
> Fixes: cdf315f907d4 ("iommu/arm-smmu-v3: Maintain a SID->device structure")
> Cc: stable@xxxxxxxxxxxxxxx
> Suggested-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
> ---
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 19 +++++++++++++++----
>  1 file changed, 15 insertions(+), 4 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>

This should go to rc as it has become urgent with the probe
reorder. Use [PATCH rc] to idicate this..

Jason