From: Lu Baolu <baolu.lu@linux.intel.com>
To: "Tian, Kevin" <kevin.tian@intel.com>,
"Pan, Jacob jun" <jacob.jun.pan@intel.com>,
"Raj, Ashok" <ashok.raj@intel.com>,
"Liu, Yi L" <yi.l.liu@intel.com>
Cc: baolu.lu@linux.intel.com,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Jacob Pan <jacob.jun.pan@linux.intel.com>
Subject: Re: [PATCH 2/3] iommu/vt-d: Drop stop marker messages
Date: Mon, 18 Apr 2022 19:37:20 +0800 [thread overview]
Message-ID: <15089cab-f896-3c4f-1986-2f84d418696b@linux.intel.com> (raw)
In-Reply-To: <BN9PR11MB52767F7FCE2E82106ABDEBBA8CF39@BN9PR11MB5276.namprd11.prod.outlook.com>
On 2022/4/18 14:58, Tian, Kevin wrote:
>> From: Lu Baolu<baolu.lu@linux.intel.com>
>> Sent: Saturday, April 16, 2022 8:31 PM
>>
>> 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. Hence, there's no need to
>> report the stop-marker message in prq_event_thread(). The stop marker
>> messages do not need a response. This drops stop marker messages silently
>> if any of them is found in the page request queue.
> The comment for iommu_queue_iopf says:
>
> * This module doesn't handle PCI PASID Stop Marker; IOMMU drivers must discard
> * them before reporting faults. A PASID Stop Marker (LRW = 0b100) doesn't
> * expect a response. It may be generated when disabling a PASID (issuing a
> * PASID stop request) by some PCI devices.
>
> So obviously the current vt-d driver behavior violates that requirement.
> Then should this be a bug fix instead?
>
Our platforms have no devices issuing Stop Marker messages yet. But in a
virtualization environment, a device might be emulated with this
capability. Yes! Let me make it as a fix.
Best regards,
baolu
next prev parent reply other threads:[~2022-04-18 11:37 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-16 12:30 [PATCH 0/3] iommu/vt-d: Some fine tuning of SVA Lu Baolu
2022-04-16 12:30 ` [PATCH 1/3] iommu/vt-d: Set PGSNP bit in pasid table entry for sva binding Lu Baolu
2022-04-18 6:56 ` Tian, Kevin
2022-04-18 11:28 ` Lu Baolu
2022-04-16 12:30 ` [PATCH 2/3] iommu/vt-d: Drop stop marker messages Lu Baolu
2022-04-18 6:58 ` Tian, Kevin
2022-04-18 11:37 ` Lu Baolu [this message]
2022-04-16 12:30 ` [PATCH 3/3] iommu/vt-d: Size Page Request Queue to avoid overflow condition Lu Baolu
2022-04-18 7:00 ` Tian, Kevin
2022-04-18 11:44 ` Lu Baolu
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