linux-kernel - Re: [PATCH v4 5/5] iommu/s390: Fix incorrect pgsize

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Message-ID: <7216693d-c354-fa0d-8f26-e2bcf76fd854@linux.ibm.com>
Date:   Tue, 4 Oct 2022 10:38:56 -0400
From:   Matthew Rosato <mjrosato@...ux.ibm.com>
To:     Niklas Schnelle <schnelle@...ux.ibm.com>,
        Pierre Morel <pmorel@...ux.ibm.com>, iommu@...ts.linux.dev
Cc:     linux-s390@...r.kernel.org, borntraeger@...ux.ibm.com,
        hca@...ux.ibm.com, gor@...ux.ibm.com,
        gerald.schaefer@...ux.ibm.com, agordeev@...ux.ibm.com,
        svens@...ux.ibm.com, joro@...tes.org, will@...nel.org,
        robin.murphy@....com, jgg@...dia.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 5/5] iommu/s390: Fix incorrect pgsize_bitmap

On 10/4/22 8:07 AM, Niklas Schnelle wrote:
> The .pgsize_bitmap property of struct iommu_ops is not a page mask but
> rather has a bit set for each size of pages the IOMMU supports. As the
> comment correctly pointed out at this moment the code only support 4K
> pages so simply use SZ_4K here.
> 
> Reviewed-by: Jason Gunthorpe <jgg@...dia.com>
> Signed-off-by: Niklas Schnelle <schnelle@...ux.ibm.com>

Reviewed-by: Matthew Rosato <mjrosato@...ux.ibm.com>

> ---
>  drivers/iommu/s390-iommu.c | 9 +--------
>  1 file changed, 1 insertion(+), 8 deletions(-)
> 
> diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c
> index 94c444b909bd..6bf23e7830a2 100644
> --- a/drivers/iommu/s390-iommu.c
> +++ b/drivers/iommu/s390-iommu.c
> @@ -12,13 +12,6 @@
>  #include <linux/sizes.h>
>  #include <asm/pci_dma.h>
>  
> -/*
> - * Physically contiguous memory regions can be mapped with 4 KiB alignment,
> - * we allow all page sizes that are an order of 4KiB (no special large page
> - * support so far).
> - */
> -#define S390_IOMMU_PGSIZES	(~0xFFFUL)
> -
>  static const struct iommu_ops s390_iommu_ops;
>  
>  struct s390_domain {
> @@ -350,7 +343,7 @@ static const struct iommu_ops s390_iommu_ops = {
>  	.probe_device = s390_iommu_probe_device,
>  	.release_device = s390_iommu_release_device,
>  	.device_group = generic_device_group,
> -	.pgsize_bitmap = S390_IOMMU_PGSIZES,
> +	.pgsize_bitmap = SZ_4K,
>  	.get_resv_regions = s390_iommu_get_resv_regions,
>  	.default_domain_ops = &(const struct iommu_domain_ops) {
>  		.attach_dev	= s390_iommu_attach_device,