linux-kernel - Re: [PATCH v14 2/6] iommu: Print strict or lazy mode at init time

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Message-ID: <502b7d81-7c6e-affd-0e06-4f0caf7e9fb9@linux.intel.com>
Date:   Fri, 18 Jun 2021 21:10:36 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     John Garry <john.garry@...wei.com>, joro@...tes.org,
        will@...nel.org, dwmw2@...radead.org, robin.murphy@....com,
        corbet@....net
Cc:     baolu.lu@...ux.intel.com, linux-kernel@...r.kernel.org,
        iommu@...ts.linux-foundation.org, linuxarm@...wei.com,
        thunder.leizhen@...wei.com, chenxiang66@...ilicon.com,
        linux-doc@...r.kernel.org
Subject: Re: [PATCH v14 2/6] iommu: Print strict or lazy mode at init time

On 2021/6/18 19:34, John Garry wrote:
> As well as the default domain type, it's useful to know whether strict
> or lazy for DMA domains, so add this info in a separate print.
> 
> The (stict/lazy) mode may be also set via iommu.strict earlyparm, but
> this will be processed prior to iommu_subsys_init(), so that print will be
> accurate for drivers which don't set the mode via custom means.
> 
> For the drivers which set the mode via custom means - AMD and Intel drivers
> - they maintain prints to inform a change in policy or that custom cmdline
> methods to change policy are deprecated.
> 
> Signed-off-by: John Garry <john.garry@...wei.com>
> Reviewed-by: Robin Murphy <robin.murphy@....com>
> ---
>   drivers/iommu/iommu.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 5419c4b9f27a..cf58949cc2f3 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -138,6 +138,11 @@ static int __init iommu_subsys_init(void)
>   		(iommu_cmd_line & IOMMU_CMD_LINE_DMA_API) ?
>   			"(set via kernel command line)" : "");
>   
> +	pr_info("DMA domain TLB invalidation policy: %s mode %s\n",
> +		iommu_dma_strict ? "strict" : "lazy",
> +		(iommu_cmd_line & IOMMU_CMD_LINE_STRICT) ?
> +			"(set via kernel command line)" : "");
> +
>   	return 0;
>   }
>   subsys_initcall(iommu_subsys_init);
> 

Reviewed-by: Lu Baolu <baolu.lu@...ux.intel.com>

Best regards,
baolu