On 2023/12/27 17:33, Ethan Zhao wrote:
On 12/27/2023 5:06 PM, Duan, Zhenzhong wrote:
-----Original Message-----
From: Liu, Yi L <yi.l.liu@xxxxxxxxx>
Sent: Tuesday, December 26, 2023 4:44 PM
Subject: Re: [PATCH v7 7/9] iommu/vt-d: Allow qi_submit_sync() to return
the QI faults
On 2023/12/26 14:15, Yi Liu wrote:
On 2023/12/26 12:13, Tian, Kevin wrote:
From: Liu, Yi L <yi.l.liu@xxxxxxxxx>
Sent: Tuesday, December 26, 2023 12:03 PM
On 2023/12/22 12:23, Tian, Kevin wrote:
From: Liu, Yi L <yi.l.liu@xxxxxxxxx>
Sent: Thursday, December 21, 2023 11:40 PM
+ fault &= DMA_FSTS_IQE | DMA_FSTS_ITE | DMA_FSTS_ICE;
+ if (fault) {
+ if (fsts)
+ *fsts |= fault;
do we expect the fault to be accumulated? otherwise it's clearer to
just do direct assignment instead of asking for the caller to clear
the variable before invocation.
not quite get. do you mean the fault should not be cleared in the caller
side?
I meant:
if (fsts)
*fsts = fault;
unless there is a reason to *OR* the original value.
I guess no such a reason. :) let me modify it.
hmmm, replied too soon. The qi_check_fault() would be called multiple
times in one invalidation circle as qi_submit_sync() needs to see if any
fault happened before the hw writes back QI_DONE to the wait descriptor.
There can be ICE which may eventually result in ITE. So caller of
qi_check_fault()
would continue to wait for QI_DONE. So qi_check_fault() returns 0 to let
qi_submit_sync() go on though ICE detected. If we use '*fsts = fault;',
then ICE would be missed since the input fsts pointer is the same in
one qi_submit_sync() call.
Is it necessary to return fault to user if qi_check_fault() return
-EAGAIN and
a restart run succeeds?
no need if a restart succeeds. I would add a *fault = 0 per the restart.
Issue a device-TLB invalidation to no response device there is possibility
will be trapped there loop for ITE , never get return.
yes. This the implementation today, in future I think we may need a kind
of timeout mechanism, so that it can return and report the error to user.
In concept, in nested translation, the page table is owned by userspace, so
it makes more sense to let userspace know it and take proper action.
--
Regards,
Yi Liu
