Re: [PATCH V4] iommu/arm-smmu-v2: Workaround for ThunderX errata#27704

[Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>]

On Thu, Mar 03, 2016 at 07:44:03PM -0800, Tirumalesh Chalamarla wrote:
> Due to Errata#27704 CN88xx SMMUv2,supports  only shared ASID and VMID
> namespaces; specifically within a given node SMMU0 and SMMU1 share,
> as does SMMU2 and SMMU3.
> 
> This patch make sures ASID and VMID space is unique across cavium SMMUv2.
> 
> changes from V3:
> 	- Removed redundent variable.

[...]

> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index 247a469..bfe38f3 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -326,6 +326,11 @@ struct arm_smmu_device {
> 
>  	struct list_head		list;
>  	struct rb_root			masters;
> +	/*
> +	 *The following fields are specific to Cavium, Thunder
> +	 */
> +	u32				cavium_id_base;
> +
>  };
> 
>  struct arm_smmu_cfg {
> @@ -335,8 +340,8 @@ struct arm_smmu_cfg {
>  };
>  #define INVALID_IRPTNDX			0xff
> 
> -#define ARM_SMMU_CB_ASID(cfg)		((cfg)->cbndx)
> -#define ARM_SMMU_CB_VMID(cfg)		((cfg)->cbndx + 1)
> +#define ARM_SMMU_CB_ASID(smmu, cfg) ((u16)(smmu)->cavium_id_base + (cfg)->cbndx)
> +#define ARM_SMMU_CB_VMID(smmu, cfg) ((u16)(smmu)->cavium_id_base + (cfg)->cbndx + 1)
> 
>  enum arm_smmu_domain_stage {
>  	ARM_SMMU_DOMAIN_S1 = 0,
> @@ -364,6 +369,8 @@ struct arm_smmu_option_prop {
>  	const char *prop;
>  };
> 
> +static u32 cavium_smmu_context_count;

I thought you were going to make this an atomic_t?

Will