From: Baolu Lu <baolu.lu@linux.intel.com>
To: Yi Liu <yi.l.liu@intel.com>, Joerg Roedel <joro@8bytes.org>,
Kevin Tian <kevin.tian@intel.com>,
Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: baolu.lu@linux.intel.com, Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
iommu@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] iommu/vt-d: Remove hardware automatic ATS dependency
Date: Mon, 24 Jun 2024 16:11:24 +0800 [thread overview]
Message-ID: <ba6b6baf-6fe7-4238-91ee-262ac006c25f@linux.intel.com> (raw)
In-Reply-To: <15590835-ed6a-44a5-94b5-663f159653cc@intel.com>
On 2024/6/24 16:06, Yi Liu wrote:
> On 2024/6/24 13:25, Lu Baolu wrote:
>> If a device is listed in the SATC table with ATC_REQUIRED flag set, it
>> indicates that the device has a functional requirement to enable its ATC
>> (via the ATS capability) for device operation. However, when IOMMU is
>> running in the legacy mode, ATS could be automatically supported by the
>> hardware so that the OS has no need to support the ATS functionality.
>
> It seems like if VT-d hw is operating in legacy mode, ATS is enabled
> automatically?
Yes.
> This is really suprising. Maybe I got it wrongly. Could you
> elaborate a bit?
It's for backward compatible purpose, but I have no hardware details.
Best regards,
baolu
next prev parent reply other threads:[~2024-06-24 8:11 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-06-24 5:25 [PATCH 1/2] iommu/vt-d: Convert dmar_ats_supported() to return bool Lu Baolu
2024-06-24 5:25 ` [PATCH 2/2] iommu/vt-d: Remove hardware automatic ATS dependency Lu Baolu
2024-06-24 8:06 ` Yi Liu
2024-06-24 8:11 ` Baolu Lu [this message]
2024-06-25 2:32 ` Tian, Kevin
2024-06-25 8:40 ` Baolu Lu
2024-06-26 1:53 ` Tian, Kevin
2024-06-26 2:37 ` Baolu Lu
2024-06-24 8:12 ` [PATCH 1/2] iommu/vt-d: Convert dmar_ats_supported() to return bool Yi Liu
2024-06-25 2:28 ` Tian, Kevin
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