From: John Garry <john.garry@huawei.com>
To: Lu Baolu <baolu.lu@linux.intel.com>, <joro@8bytes.org>,
<will@kernel.org>, <dwmw2@infradead.org>, <robin.murphy@arm.com>,
<corbet@lwn.net>
Cc: <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: Thu, 17 Jun 2021 08:41:24 +0100 [thread overview]
Message-ID: <c61376c8-5285-1121-046f-3ab12eee9902@huawei.com> (raw)
In-Reply-To: <de6a2874-3d6d-ed2a-78f5-fb1fb0195228@linux.intel.com>
>> @@ -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.
Thanks,
john
next prev parent reply other threads:[~2021-06-17 7:47 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 [this message]
2021-06-18 1:52 ` Lu Baolu
2021-06-17 18:56 ` Robin Murphy
2021-06-18 1:51 ` Lu Baolu
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