Re: [PATCH v3 15/16] iommu/amd: Initialize iommu_device->max_pasids

[Jason Gunthorpe <jgg@ziepe.ca>]

On Fri, Aug 04, 2023 at 06:42:15AM +0000, Vasant Hegde wrote:
> Commit 1adf3cc20d69 ("iommu: Add max_pasids field in struct iommu_device")
> introduced a variable struct iommu_device.max_pasids to track max
> PASIDS supported by each IOMMU.
> 
> Let us initialize this field for AMD IOMMU. IOMMU core will use this value
> to set max PASIDs per device (see __iommu_probe_device()).
> 
> Also remove unused global 'amd_iommu_max_pasid' variable.
> 
> Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
> ---
>  drivers/iommu/amd/amd_iommu_types.h | 3 ---
>  drivers/iommu/amd/init.c            | 9 ++-------
>  2 files changed, 2 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/iommu/amd/amd_iommu_types.h b/drivers/iommu/amd/amd_iommu_types.h
> index e114e4af0f05..0d339e022572 100644
> --- a/drivers/iommu/amd/amd_iommu_types.h
> +++ b/drivers/iommu/amd/amd_iommu_types.h
> @@ -895,9 +895,6 @@ extern unsigned amd_iommu_aperture_order;
>  /* allocation bitmap for domain ids */
>  extern unsigned long *amd_iommu_pd_alloc_bitmap;
>  
> -/* Smallest max PASID supported by any IOMMU in the system */
> -extern u32 amd_iommu_max_pasid;
> -
>  extern bool amd_iommu_force_isolation;
>  
>  /* Max levels of glxval supported */
> diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
> index 1f56478ae74e..e0b0e48d3d38 100644
> --- a/drivers/iommu/amd/init.c
> +++ b/drivers/iommu/amd/init.c
> @@ -185,8 +185,6 @@ static int amd_iommus_present;
>  bool amd_iommu_np_cache __read_mostly;
>  bool amd_iommu_iotlb_sup __read_mostly = true;
>  
> -u32 amd_iommu_max_pasid __read_mostly = ~0;
> -
>  static bool amd_iommu_pc_present __read_mostly;
>  bool amdr_ivrs_remap_support __read_mostly;
>  
> @@ -2086,16 +2084,13 @@ static int __init iommu_init_pci(struct amd_iommu *iommu)
>  
>  	if (iommu_feature(iommu, FEATURE_GT)) {
>  		int glxval;
> -		u32 max_pasid;
>  		u64 pasmax;
>  
>  		pasmax = iommu->features & FEATURE_PASID_MASK;
>  		pasmax >>= FEATURE_PASID_SHIFT;
> -		max_pasid  = (1 << (pasmax + 1)) - 1;
> -
> -		amd_iommu_max_pasid = min(amd_iommu_max_pasid, max_pasid);
> +		iommu->iommu.max_pasids = (1 << (pasmax + 1)) - 1;
>  
> -		BUG_ON(amd_iommu_max_pasid & ~PASID_MASK);
> +		BUG_ON(iommu->iommu.max_pasids & ~PASID_MASK);

You said you'd fix this to remove the BUG_ON.

Jason