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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

WARNING: multiple messages have this Message-ID
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: linux-doc@vger.kernel.org, linuxarm@huawei.com,
	linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.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
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

  reply	other threads:[~2021-06-18  1:54 UTC|newest]

Thread overview: 38+ 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 ` John Garry
2021-06-16 11:03 ` [PATCH v13 1/6] iommu: Deprecate Intel and AMD cmdline methods to enable strict mode John Garry
2021-06-16 11:03   ` John Garry
2021-06-17 19:01   ` Robin Murphy
2021-06-17 19:01     ` Robin Murphy
2021-06-18  7:43     ` John Garry
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   ` 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   ` John Garry
2021-06-16 11:03 ` [PATCH v13 4/6] iommu/vt-d: Add support for " John Garry
2021-06-16 11:03   ` John Garry
2021-06-17  7:32   ` Lu Baolu
2021-06-17  7:32     ` Lu Baolu
2021-06-17  8:00     ` John Garry
2021-06-17  8:00       ` John Garry
2021-06-17 19:03       ` Robin Murphy
2021-06-17 19:03         ` Robin Murphy
2021-06-18  1:46       ` Lu Baolu
2021-06-18  1:46         ` Lu Baolu
2021-06-18  7:31         ` John Garry
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   ` John Garry
2021-06-16 11:03 ` [PATCH v13 6/6] iommu: Remove mode argument from iommu_set_dma_strict() John Garry
2021-06-16 11:03   ` John Garry
2021-06-17  7:36   ` Lu Baolu
2021-06-17  7:36     ` Lu Baolu
2021-06-17  7:41     ` John Garry
2021-06-17  7:41       ` John Garry
2021-06-18  1:52       ` Lu Baolu [this message]
2021-06-18  1:52         ` Lu Baolu
2021-06-17 18:56     ` Robin Murphy
2021-06-17 18:56       ` Robin Murphy
2021-06-18  1:51       ` Lu Baolu
2021-06-18  1:51         ` Lu Baolu

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