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From: Jacob Pan <jacob.jun.pan@linux.intel.com>
To: "Liu, Yi L" <yi.l.liu@intel.com>
Cc: "iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Joerg Roedel <joro@8bytes.org>,
	"David Woodhouse" <dwmw2@infradead.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Alex Williamson <alex.williamson@redhat.com>,
	Jean-Philippe Brucker <jean-philippe.brucker@arm.com>,
	"Wysocki, Rafael J" <rafael.j.wysocki@intel.com>,
	"Tian, Kevin" <kevin.tian@intel.com>,
	"Raj, Ashok" <ashok.raj@intel.com>,
	Jean Delvare <khali@linux-fr.org>,
	Christoph Hellwig <hch@infradead.org>,
	Lu Baolu <baolu.lu@linux.intel.com>,
	jacob.jun.pan@linux.intel.com
Subject: Re: [PATCH v5 13/23] iommu: introduce device fault report API
Date: Thu, 17 May 2018 08:59:09 -0700	[thread overview]
Message-ID: <20180517085909.7470dfb5@jacob-builder> (raw)
In-Reply-To: <A2975661238FB949B60364EF0F2C257439BF2537@SHSMSX104.ccr.corp.intel.com>

On Thu, 17 May 2018 11:41:56 +0000
"Liu, Yi L" <yi.l.liu@intel.com> wrote:

> > +int iommu_report_device_fault(struct device *dev, struct
> > +iommu_fault_event *evt) {
> > +	int ret = 0;
> > +	struct iommu_fault_event *evt_pending;
> > +	struct iommu_fault_param *fparam;
> > +
> > +	/* iommu_param is allocated when device is added to group
> > */
> > +	if (!dev->iommu_param | !evt)
> > +		return -EINVAL;
> > +	/* we only report device fault if there is a handler
> > registered */
> > +	mutex_lock(&dev->iommu_param->lock);
> > +	if (!dev->iommu_param->fault_param ||
> > +		!dev->iommu_param->fault_param->handler) {
> > +		ret = -EINVAL;
> > +		goto done_unlock;
> > +	}
> > +	fparam = dev->iommu_param->fault_param;
> > +	if (evt->type == IOMMU_FAULT_PAGE_REQ && evt->last_req) {
> > +		evt_pending = kmemdup(evt, sizeof(struct
> > iommu_fault_event),
> > +				GFP_KERNEL);
> > +		if (!evt_pending) {
> > +			ret = -ENOMEM;
> > +			goto done_unlock;
> > +		}
> > +		mutex_lock(&fparam->lock);
> > +		list_add_tail(&evt_pending->list,
> > &fparam->faults);  
> 
> I may missed it. Here only see list add, how about removing? Who
> would remove entry from the fault list?
> 
deletion of the pending event is in page response function (int
iommu_page_response), once iommu driver finds a matching response for
the pending request, it will delete the pending event.

if the response never came, right now we don't delete it, just gives
warning.

> > +		mutex_unlock(&fparam->lock);
> > +	}
> > +	ret = fparam->handler(evt, fparam->data);  
> 
> I remember you mentioned there will be a queue to store the faults.
> Is it in the fparam->faults list? Or there is no such queue?
There are two use cases:
case A: guest SVA, PRQ events are reported outside IOMMU subsystem,
	e.g. vfio
case B: in-kernel

The io page fault queuing is Jean's patchset, mostly for case
B (in-kernel IO page fault handling). I will convert intel-svm to Jean's
io page fault mechanism so that we can also have parallel and out of
order queuing of PRQ. I still need some time to evaluate intel specific
needs such as streaming page request/response.

For case A, there is no queuing in host IOMMU driver. My understanding
of the flow is as the following:
1. host IOMMU receives PRQ
2. host IOMMU driver reports PRQ fault event to registered called, i.e.
vfio
3. VFIO reports fault event to QEMU
4. QEMU injects PRQ to guest
5. Guest IOMMU driver receives PRQ in IRQ
6. Guest IOMMU driver queue PRQ by groups, PASID.
So as long as in-kernel PRQ handling can do queuing, there is no need
for queuing in the host reporting path.

Jacob

  reply	other threads:[~2018-05-17 15:56 UTC|newest]

Thread overview: 81+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-11 20:53 [PATCH v5 00/23] IOMMU and VT-d driver support for Shared Virtual Address (SVA) Jacob Pan
2018-05-11 20:53 ` [PATCH v5 01/23] iommu: introduce bind_pasid_table API function Jacob Pan
2018-08-23 16:34   ` Auger Eric
2018-08-24 12:47     ` Liu, Yi L
2018-08-24 13:20       ` Auger Eric
2018-08-28 17:04         ` Jacob Pan
2018-08-24 15:00   ` Auger Eric
2018-08-28  5:14     ` Jacob Pan
2018-08-28  8:34       ` Auger Eric
2018-08-28 16:36         ` Jacob Pan
2018-05-11 20:53 ` [PATCH v5 02/23] iommu/vt-d: move device_domain_info to header Jacob Pan
2018-05-11 20:53 ` [PATCH v5 03/23] iommu/vt-d: add a flag for pasid table bound status Jacob Pan
2018-05-13  7:33   ` Lu Baolu
2018-05-14 18:51     ` Jacob Pan
2018-05-13  8:01   ` Lu Baolu
2018-05-14 18:52     ` Jacob Pan
2018-05-11 20:53 ` [PATCH v5 04/23] iommu/vt-d: add bind_pasid_table function Jacob Pan
2018-05-13  9:29   ` Lu Baolu
2018-05-14 20:22     ` Jacob Pan
2018-05-11 20:53 ` [PATCH v5 05/23] iommu: introduce iommu invalidate API function Jacob Pan
2018-05-11 20:53 ` [PATCH v5 06/23] iommu/vt-d: add definitions for PFSID Jacob Pan
2018-05-14  1:36   ` Lu Baolu
2018-05-14 20:30     ` Jacob Pan
2018-05-11 20:53 ` [PATCH v5 07/23] iommu/vt-d: fix dev iotlb pfsid use Jacob Pan
2018-05-14  1:52   ` Lu Baolu
2018-05-14 20:38     ` Jacob Pan
2018-05-11 20:54 ` [PATCH v5 08/23] iommu/vt-d: support flushing more translation cache types Jacob Pan
2018-05-14  2:18   ` Lu Baolu
2018-05-14 20:46     ` Jacob Pan
2018-05-17  8:44   ` kbuild test robot
2018-05-11 20:54 ` [PATCH v5 09/23] iommu/vt-d: add svm/sva invalidate function Jacob Pan
2018-05-14  3:35   ` Lu Baolu
2018-05-14 20:49     ` Jacob Pan
2018-05-11 20:54 ` [PATCH v5 10/23] iommu: introduce device fault data Jacob Pan
2018-09-21 10:07   ` Auger Eric
2018-09-21 17:05     ` Jacob Pan
2018-09-26 10:20       ` Auger Eric
2018-05-11 20:54 ` [PATCH v5 11/23] driver core: add per device iommu param Jacob Pan
2018-05-14  5:27   ` Lu Baolu
2018-05-14 20:52     ` Jacob Pan
2018-05-11 20:54 ` [PATCH v5 12/23] iommu: add a timeout parameter for prq response Jacob Pan
2018-05-11 20:54 ` [PATCH v5 13/23] iommu: introduce device fault report API Jacob Pan
2018-05-14  6:01   ` Lu Baolu
2018-05-14 20:55     ` Jacob Pan
2018-05-15  6:52       ` Lu Baolu
2018-05-17 11:41   ` Liu, Yi L
2018-05-17 15:59     ` Jacob Pan [this message]
2018-05-17 23:22       ` Liu, Yi L
2018-05-21 23:03         ` Jacob Pan
2018-09-06  9:25   ` Auger Eric
2018-09-06 12:42     ` Jean-Philippe Brucker
2018-09-06 13:14       ` Auger Eric
2018-09-06 17:06         ` Jean-Philippe Brucker
2018-09-07  7:11           ` Auger Eric
2018-09-07 11:23             ` Jean-Philippe Brucker
2018-09-14 13:24   ` Auger Eric
2018-09-17 16:57     ` Jacob Pan
2018-09-25 14:58   ` Jean-Philippe Brucker
2018-09-25 22:17     ` Jacob Pan
2018-09-26 10:14       ` Jean-Philippe Brucker
2018-05-11 20:54 ` [PATCH v5 14/23] iommu: introduce page response function Jacob Pan
2018-05-14  6:39   ` Lu Baolu
2018-05-29 16:13     ` Jacob Pan
2018-09-10 14:52   ` Auger Eric
2018-09-10 17:50     ` Jacob Pan
2018-09-10 19:06       ` Auger Eric
2018-05-11 20:54 ` [PATCH v5 15/23] iommu: handle page response timeout Jacob Pan
2018-05-14  7:43   ` Lu Baolu
2018-05-29 16:20     ` Jacob Pan
2018-05-30  7:46       ` Lu Baolu
2018-05-11 20:54 ` [PATCH v5 16/23] iommu/config: add build dependency for dmar Jacob Pan
2018-05-11 20:54 ` [PATCH v5 17/23] iommu/vt-d: report non-recoverable faults to device Jacob Pan
2018-05-14  8:17   ` Lu Baolu
2018-05-29 17:33     ` Jacob Pan
2018-05-11 20:54 ` [PATCH v5 18/23] iommu/intel-svm: report device page request Jacob Pan
2018-05-11 20:54 ` [PATCH v5 19/23] iommu/intel-svm: replace dev ops with fault report API Jacob Pan
2018-05-11 20:54 ` [PATCH v5 20/23] iommu/intel-svm: do not flush iotlb for viommu Jacob Pan
2018-05-11 20:54 ` [PATCH v5 21/23] iommu/vt-d: add intel iommu page response function Jacob Pan
2018-05-11 20:54 ` [PATCH v5 22/23] trace/iommu: add sva trace events Jacob Pan
2018-05-11 20:54 ` [PATCH v5 23/23] iommu: use sva invalidate and device fault trace event Jacob Pan
2018-05-29 15:54 ` [PATCH v5 00/23] IOMMU and VT-d driver support for Shared Virtual Address (SVA) Jacob Pan

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