From: Lu Baolu <baolu.lu@linux.intel.com>
To: John Garry <john.garry@huawei.com>,
joro@8bytes.org, will@kernel.org, dwmw2@infradead.org,
robin.murphy@arm.com, corbet@lwn.net
Cc: baolu.lu@linux.intel.com, linux-kernel@vger.kernel.org,
iommu@lists.linux-foundation.org, linuxarm@huawei.com,
thunder.leizhen@huawei.com, chenxiang66@hisilicon.com,
linux-doc@vger.kernel.org
Subject: Re: [PATCH v13 6/6] iommu: Remove mode argument from iommu_set_dma_strict()
Date: Fri, 18 Jun 2021 09:52:29 +0800 [thread overview]
Message-ID: <cac021f9-8469-a3b4-a0c6-80a37e882b6f@linux.intel.com> (raw)
In-Reply-To: <c61376c8-5285-1121-046f-3ab12eee9902@huawei.com>
On 6/17/21 3:41 PM, John Garry wrote:
>
>>> @@ -349,10 +349,9 @@ 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))
>>> - iommu_dma_strict = strict;
>>> + iommu_dma_strict = true;
>>
>> Sorry, I still can't get how iommu.strict kernel option works.
>>
>> static int __init iommu_dma_setup(char *str)
>> {
>> int ret = kstrtobool(str, &iommu_dma_strict);
>>
>> if (!ret)
>> iommu_cmd_line |= IOMMU_CMD_LINE_STRICT;
>> return ret;
>> }
>> early_param("iommu.strict", iommu_dma_setup);
>>
>> The bit IOMMU_CMD_LINE_STRICT is only set, but not used anywhere.
>
> It is used in patch 2/6:
>
> + 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)" : "");
>
>> Hence,
>> I am wondering how could it work? A bug or I missed anything?
>
> It is really just used for informative purpose now.
I am clear now. Thanks!
Best regards,
baolu
next prev parent reply other threads:[~2021-06-18 1:54 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-16 11:03 [PATCH v13 0/6] iommu: Enhance IOMMU default DMA mode build options John Garry
2021-06-16 11:03 ` [PATCH v13 1/6] iommu: Deprecate Intel and AMD cmdline methods to enable strict mode John Garry
2021-06-17 19:01 ` Robin Murphy
2021-06-18 7:43 ` John Garry
2021-06-16 11:03 ` [PATCH v13 2/6] iommu: Print strict or lazy mode at init time John Garry
2021-06-16 11:03 ` [PATCH v13 3/6] iommu: Enhance IOMMU default DMA mode build options John Garry
2021-06-16 11:03 ` [PATCH v13 4/6] iommu/vt-d: Add support for " John Garry
2021-06-17 7:32 ` Lu Baolu
2021-06-17 8:00 ` John Garry
2021-06-17 19:03 ` Robin Murphy
2021-06-18 1:46 ` Lu Baolu
2021-06-18 7:31 ` John Garry
2021-06-16 11:03 ` [PATCH v13 5/6] iommu/amd: " John Garry
2021-06-16 11:03 ` [PATCH v13 6/6] iommu: Remove mode argument from iommu_set_dma_strict() John Garry
2021-06-17 7:36 ` Lu Baolu
2021-06-17 7:41 ` John Garry
2021-06-18 1:52 ` Lu Baolu [this message]
2021-06-17 18:56 ` Robin Murphy
2021-06-18 1:51 ` Lu Baolu
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