Re: [PATCH v3 06/16] iommu/amd: Introduce helper functions for managing GCR3 table

[Jason Gunthorpe <jgg@ziepe.ca>]

On Fri, Aug 04, 2023 at 06:42:06AM +0000, Vasant Hegde wrote:
> From: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
> 
> Refactor domain_enable_v2() into helper functions for managing GCR3 table
> (i.e. setup_gcr3_table() and get_gcr3_levels()), which will be used in
> subsequent patches. Also re-arrange code and remove forward declaration.
> 
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
> Co-developed-by: Vasant Hegde <vasant.hegde@amd.com>
> Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
> ---
>  drivers/iommu/amd/iommu.c | 66 +++++++++++++++++++++++----------------
>  1 file changed, 39 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
> index d5569eec0fe9..135fa087ce47 100644
> --- a/drivers/iommu/amd/iommu.c
> +++ b/drivers/iommu/amd/iommu.c
> @@ -77,7 +77,6 @@ struct iommu_cmd {
>  struct kmem_cache *amd_iommu_irq_cache;
>  
>  static void detach_device(struct device *dev);
> -static int domain_enable_v2(struct protection_domain *domain, int pasids);
>  
>  /****************************************************************************
>   *
> @@ -1575,6 +1574,43 @@ static void free_gcr3_table(struct protection_domain *domain)
>  	free_page((unsigned long)domain->gcr3_tbl);
>  }
>  
> +static int get_gcr3_levels(int pasids)
> +{
> +	int levels = 0;
> +
> +	if (pasids == -1)
> +		return amd_iommu_max_glx_val;
> +
> +	/*
> +	 * Number of GCR3 table levels required. Level must be 4-Kbyte
> +	 * page and can contain upto 512 entries.
> +	 */
> +	for ( ; get_count_order(pasids) >= 9; pasids >>= 9)
> +		levels += 1;
> +
> +	return levels;

You missed to use the DIV_ROUND_UP

Jason