linux-kernel - Re: [PATCH v2 3/4] iommu/vt-d: Drop stop marker messages

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Date:   Sat, 23 Apr 2022 15:32:21 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     "Tian, Kevin" <kevin.tian@...el.com>,
        "Pan, Jacob jun" <jacob.jun.pan@...el.com>,
        "Raj, Ashok" <ashok.raj@...el.com>,
        "Liu, Yi L" <yi.l.liu@...el.com>
Cc:     "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>
Subject: Re: [PATCH v2 3/4] iommu/vt-d: Drop stop marker messages

On 2022/4/22 11:05, Tian, Kevin wrote:
>> From: Lu Baolu<baolu.lu@...ux.intel.com>
>> Sent: Thursday, April 21, 2022 7:36 PM
>>
>> The page fault handling framework in the IOMMU core explicitly states
>> that it doesn't handle PCI PASID Stop Marker and the IOMMU drivers must
>> discard them before reporting faults. This handles Stop Marker messages
>> in prq_event_thread() before reporting events to the core.
>>
>> The VT-d driver explicitly drains the pending page requests when a CPU
>> page table (represented by a mm struct) is unbound from a PASID according
>> to the procedures defined in the VT-d spec. The Stop Marker messages do
>> not need a response. Hence, it is safe to drop the Stop Marker messages
>> silently if any of them is found in the page request queue.
>>
>> Fixes: d5b9e4bfe0d88 ("iommu/vt-d: Report prq to io-pgfault framework")
>> Signed-off-by: Lu Baolu<baolu.lu@...ux.intel.com>
>> Reviewed-by: Jacob Pan<jacob.jun.pan@...ux.intel.com>
> Reviewed-by: Kevin Tian<kevin.tian@...el.com>
> 

Thank you, Kevin. I will queue this patch to Joerg as a fix for v5.18.

Best regards,
baolu