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

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Date:   Mon, 14 Jun 2021 15:19:57 +0100
From:   John Garry <john.garry@...wei.com>
To:     Robin Murphy <robin.murphy@....com>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        "joro@...tes.org" <joro@...tes.org>,
        "will@...nel.org" <will@...nel.org>,
        "dwmw2@...radead.org" <dwmw2@...radead.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        Linuxarm <linuxarm@...wei.com>,
        "Leizhen (ThunderTown)" <thunder.leizhen@...wei.com>,
        "chenxiang (M)" <chenxiang66@...ilicon.com>
Subject: Re: [PATCH v12 3/5] iommu/vt-d: Add support for IOMMU default DMA
 mode build options

On 14/06/2021 15:11, Robin Murphy wrote:
> On 2021-06-14 08:53, John Garry wrote:
>> 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.
> Oops, I should have documented that "iommu.strict" already applies to
> x86 as well. The interaction with the driver-specific parameters is a
> bit weird and unintuitive, but it was done knowingly. Let me quickly
> spin a kernel-parameters.txt fix for that...

So I already had a pending patch here for the same to be included in 
this series:
https://github.com/hisilicon/kernel-dev/commit/2375a2d888d78de9eb7d91d6f2c5891395300a96

If you want to do it, then ok. I might have to reorder the series though...

Thanks,
John