linux-kernel - Re: [PATCH v12 5/5] iommu: Remove mode argument from iommu_set_dma

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Message-ID: <868374d4-e816-b607-82de-7e7c27a4c66b@arm.com>
Date:   Mon, 14 Jun 2021 17:25:09 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     John Garry <john.garry@...wei.com>, joro@...tes.org,
        will@...nel.org, dwmw2@...radead.org, baolu.lu@...ux.intel.com
Cc:     linux-kernel@...r.kernel.org, iommu@...ts.linux-foundation.org,
        linuxarm@...wei.com, thunder.leizhen@...wei.com,
        chenxiang66@...ilicon.com
Subject: Re: [PATCH v12 5/5] iommu: Remove mode argument from
 iommu_set_dma_strict()

On 2021-06-11 13:20, John Garry wrote:
> We only ever now set strict mode enabled in iommu_set_dma_strict(), so
> just remove the argument.
> 
> Signed-off-by: John Garry <john.garry@...wei.com>
> ---
>   drivers/iommu/amd/init.c    | 2 +-
>   drivers/iommu/intel/iommu.c | 6 +++---
>   drivers/iommu/iommu.c       | 5 ++---
>   include/linux/iommu.h       | 2 +-
>   4 files changed, 7 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
> index 0e6ae6d68f14..27e9677ec303 100644
> --- a/drivers/iommu/amd/init.c
> +++ b/drivers/iommu/amd/init.c
> @@ -3098,7 +3098,7 @@ static int __init parse_amd_iommu_options(char *str)
>   {
>   	for (; *str; ++str) {
>   		if (strncmp(str, "fullflush", 9) == 0)
> -			iommu_set_dma_strict(true);
> +			iommu_set_dma_strict();
>   		if (strncmp(str, "force_enable", 12) == 0)
>   			amd_iommu_force_enable = true;
>   		if (strncmp(str, "off", 3) == 0)
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index 6763e516362c..e77b8b6e7838 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -452,7 +452,7 @@ static int __init intel_iommu_setup(char *str)
>   			pr_warn("intel_iommu=forcedac deprecated; use iommu.forcedac instead\n");
>   			iommu_dma_forcedac = true;
>   		} else if (!strncmp(str, "strict", 6)) {
> -			iommu_set_dma_strict(true);
> +			iommu_set_dma_strict();
>   		} else if (!strncmp(str, "sp_off", 6)) {
>   			pr_info("Disable supported super page\n");
>   			intel_iommu_superpage = 0;
> @@ -4392,7 +4392,7 @@ int __init intel_iommu_init(void)
>   		 */
>   		if (cap_caching_mode(iommu->cap)) {
>   			pr_warn("IOMMU batching disallowed due to virtualization\n");
> -			iommu_set_dma_strict(true);
> +			iommu_set_dma_strict();
>   		}
>   		iommu_device_sysfs_add(&iommu->iommu, NULL,
>   				       intel_iommu_groups,
> @@ -5663,7 +5663,7 @@ static void quirk_calpella_no_shadow_gtt(struct pci_dev *dev)
>   	} else if (dmar_map_gfx) {
>   		/* we have to ensure the gfx device is idle before we flush */
>   		pci_info(dev, "Disabling batched IOTLB flush on Ironlake\n");
> -		iommu_set_dma_strict(true);
> +		iommu_set_dma_strict();
>   	}
>   }
>   DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x0040, quirk_calpella_no_shadow_gtt);
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index ccbd5d4c1a50..146cb71c7441 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -350,10 +350,9 @@ static int __init iommu_dma_setup(char *str)
>   }
>   early_param("iommu.strict", iommu_dma_setup);
>   
> -void iommu_set_dma_strict(bool strict)
> +void iommu_set_dma_strict(void)
>   {
> -	if (strict || !(iommu_cmd_line & IOMMU_CMD_LINE_STRICT))

We shouldn't need to keep IOMMU_CMD_LINE_STRICT at all now, since it was 
only to prevent a driver's "default lazy" setting passed in here from 
downgrading an explicitly-set strict mode.

With that cleaned up too,

Reviewed-by: Robin Murphy <robin.murphy@....com>

Thanks,
Robin.

> -		iommu_dma_strict = strict;
> +		iommu_dma_strict = true;
>   }
>   
>   bool iommu_get_dma_strict(struct iommu_domain *domain)
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 32d448050bf7..754f67d6dd90 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -476,7 +476,7 @@ int iommu_enable_nesting(struct iommu_domain *domain);
>   int iommu_set_pgtable_quirks(struct iommu_domain *domain,
>   		unsigned long quirks);
>   
> -void iommu_set_dma_strict(bool val);
> +void iommu_set_dma_strict(void);
>   bool iommu_get_dma_strict(struct iommu_domain *domain);
>   
>   extern int report_iommu_fault(struct iommu_domain *domain, struct device *dev,
>