[PATCH] iommu/arm-smmu-v3: Cope with duplicated Stream IDs

[tn]

Hi Robin,

Thank you for fixing this.

Regards,
Tomasz

On 02.01.2018 13:33, Robin Murphy wrote:
> For PCI devices behind an aliasing PCIe-to-PCI/X bridge, the bridge
> alias to DevFn 0.0 on the subordinate bus may match the original RID of
> the device, resulting in the same SID being present in the device's
> fwspec twice. This causes trouble later in arm_smmu_write_strtab_ent()
> when we wind up visiting the STE a second time and find it already live.
> 
> Avoid the issue by giving arm_smmu_install_ste_for_dev() the cleverness
> to skip over duplicates. It seems mildly counterintuitive compared to
> preventing the duplicates from existing in the first place, but since
> the DT and ACPI probe paths build their fwspecs differently, this is
> actually the cleanest and most self-contained way to deal with it.
> 
> Fixes: 8f78515425da ("iommu/arm-smmu: Implement of_xlate() for SMMUv3")
> Reported-by: Tomasz Nowicki <tomasz.nowicki at caviumnetworks.com>
> Tested-by: Tomasz Nowicki <Tomasz.Nowicki at cavium.com>
> Tested-by: Jayachandran C. <jnair at caviumnetworks.com>
> Signed-off-by: Robin Murphy <robin.murphy at arm.com>
> ---
>   drivers/iommu/arm-smmu-v3.c | 9 ++++++++-
>   1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
> index 9ce3cde575a8..57c92aa3122e 100644
> --- a/drivers/iommu/arm-smmu-v3.c
> +++ b/drivers/iommu/arm-smmu-v3.c
> @@ -1752,7 +1752,7 @@ static __le64 *arm_smmu_get_step_for_sid(struct arm_smmu_device *smmu, u32 sid)
>   
>   static void arm_smmu_install_ste_for_dev(struct iommu_fwspec *fwspec)
>   {
> -	int i;
> +	int i, j;
>   	struct arm_smmu_master_data *master = fwspec->iommu_priv;
>   	struct arm_smmu_device *smmu = master->smmu;
>   
> @@ -1760,6 +1760,13 @@ static void arm_smmu_install_ste_for_dev(struct iommu_fwspec *fwspec)
>   		u32 sid = fwspec->ids[i];
>   		__le64 *step = arm_smmu_get_step_for_sid(smmu, sid);
>   
> +		/* Bridged PCI devices may end up with duplicated IDs */
> +		for (j = 0; j < i; j++)
> +			if (fwspec->ids[j] == sid)
> +				break;
> +		if (j < i)
> +			continue;
> +
>   		arm_smmu_write_strtab_ent(smmu, sid, step, &master->ste);
>   	}
>   }
>