On 2022/4/18 14:58, Tian, Kevin wrote:
From: Lu Baolu<[email protected]>
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
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