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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 14 Jun 2021 09:03:43 +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 03:14, Lu Baolu wrote:
> On 2021/6/11 20:20, John Garry wrote:
>> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
>> index 2a71347611d4..4467353f981b 100644
>> --- a/drivers/iommu/Kconfig
>> +++ b/drivers/iommu/Kconfig
>> @@ -94,6 +94,7 @@ choice
>>       prompt "IOMMU default DMA mode"
>>       depends on IOMMU_DMA
>> +    default IOMMU_DEFAULT_LAZY if INTEL_IOMMU
>>       default IOMMU_DEFAULT_STRICT
> 
> If two default values are different. Which one will be overridden?

If I understand your question correctly, I think you are asking if both 
are set:
CONFIG_IOMMU_DEFAULT_LAZY=y
CONFIG_IOMMU_DEFAULT_STRICT=y

If this happens, then make defconfig complains about both being set, and 
selects the 2nd, whatever that is.

If neither are set, then IOMMU_DEFAULT_LAZY is set if INTEL_IOMMU is 
set, otherwise IOMMU_DEFAULT_STRICT.

Thanks,
John