linux-kernel - Re: [PATCH v12 3/5] iommu/vt-d: Add support for IOMMU default DMA mode build options

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Message-ID: <6055cd0d-a1d3-a73a-6831-3837021f3c9c@huawei.com>
Date:   Mon, 14 Jun 2021 08:53:08 +0100
From:   John Garry <john.garry@...wei.com>
To:     Lu Baolu <baolu.lu@...ux.intel.com>, <joro@...tes.org>,
        <will@...nel.org>, <dwmw2@...radead.org>, <robin.murphy@....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 3/5] iommu/vt-d: Add support for IOMMU default DMA
 mode build options

On 12/06/2021 03:22, Lu Baolu wrote:
> On 2021/6/11 20:20, John Garry wrote:
>> @@ -453,8 +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)) {
>> -            pr_info("Disable batched IOTLB flush\n");
>> -            intel_iommu_strict = 1;
>> +            iommu_set_dma_strict(true);
> 
> I would like to deprecate this command line and ask users to use
> iommu.strict instead.

ok, but then I should probably make the AMD driver also officially 
support this.

> 
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -436,7 +436,7 @@ 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)) {
> -                       pr_info("Disable batched IOTLB flush\n");
> +                       pr_warn("intel_iommu=strict deprecated; use 
> iommu.strict instead\n");
>                          intel_iommu_strict = 1;
> 
> Also update Documentation/admin-guide/kernel-parameters.txt accordingly.

Thanks,
John