Joerg, On 1/16/19 8:03 PM, j...@8bytes.org wrote: > Hi Suravee, > > On Wed, Jan 16, 2019 at 04:15:10AM +0000, Suthikulpanit, Suravee wrote: >> From: Suravee Suthikulpanit <suravee.suthikulpa...@amd.com> >> >> When a device switches domain, IOMMU driver detach device from the old >> domain, and attach device to the new domain. During this period >> the host table root pointer is not set, which means DMA translation >> should be marked as invalid (clear TV bit). >> >> So, clear the TV bit when detach the device. The TV bit will be set >> again when attaching device to the new domain. > > Is there a specific problem with setting the TV bit?
We are not currently seeing issue. > Note that the update will clear all other fields in the first 128 bits > of the DTE, which means that IR, IW and Mode are all set to 0. This > effectivly blocks all DMA requests from the device, which is by design. Ahh.. This makes sense now. I missed the IR/IW/Mode=0 part. It was not clear to us earlier. Thanks for clarification. Regards, Suravee