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From: "Liu, Yi L" <yi.l.liu@intel.com>
To: Jacob Pan <jacob.jun.pan@linux.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>
Subject: RE: [PATCH v5 13/23] iommu: introduce device fault report API
Date: Thu, 17 May 2018 23:22:43 +0000	[thread overview]
Message-ID: <A2975661238FB949B60364EF0F2C257439BF2B2D@SHSMSX104.ccr.corp.intel.com> (raw)
In-Reply-To: <20180517085909.7470dfb5@jacob-builder>

> From: Jacob Pan [mailto:jacob.jun.pan@linux.intel.com]
> Sent: Thursday, May 17, 2018 11:59 PM
> 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.

Got it.

> 
> > > +		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.

Correct.

> So as long as in-kernel PRQ handling can do queuing, there is no need for queuing in
> the host reporting path.

Will it affect current interface? Here the handler only get an "evt" per a PRQ IRQ. And I suppose
vfio needs not rely on host iommu queuing?

Thanks,
Yi Liu

  reply	other threads:[~2018-05-17 23:22 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
2018-05-17 23:22       ` Liu, Yi L [this message]
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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