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From: Alex Williamson <alex.williamson@redhat.com>
To: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Jean-Philippe Brucker <Jean-Philippe.Brucker@arm.com>,
	"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>,
	Rafael Wysocki <rafael.j.wysocki@intel.com>,
	"Liu, Yi L" <yi.l.liu@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>,
	Yi L <yi.l.liu@linux.intel.com>
Subject: Re: [PATCH v4 04/22] iommu/vt-d: add bind_pasid_table function
Date: Tue, 29 May 2018 14:09:15 -0600	[thread overview]
Message-ID: <20180529140915.1f174689@w520.home> (raw)
In-Reply-To: <20180420164251.5245f822@jacob-builder>

On Fri, 20 Apr 2018 16:42:51 -0700
Jacob Pan <jacob.jun.pan@linux.intel.com> wrote:

> On Fri, 20 Apr 2018 19:25:34 +0100
> Jean-Philippe Brucker <Jean-Philippe.Brucker@arm.com> wrote:
> 
> > On Tue, Apr 17, 2018 at 08:10:47PM +0100, Alex Williamson wrote:
> > [...]  
> > > > +	/* Assign guest PASID table pointer and size order */
> > > > +	ctx_lo = (pasidt_binfo->base_ptr & VTD_PAGE_MASK) |
> > > > +		(pasidt_binfo->pasid_bits - MIN_NR_PASID_BITS);    
> > > 
> > > Where does this IOMMU API interface define that base_ptr is 4K
> > > aligned or the format of the PASID table?  Are these all
> > > standardized or do they vary by host IOMMU?  If they're standards,
> > > maybe we could note that and the spec which defines them when we
> > > declare base_ptr.  If they're IOMMU specific then I don't
> > > understand how we'll match a user provided PASID table to the
> > > requirements and format of the host IOMMU. Thanks,    
> > 
> > On SMMUv3 the minimum alignment for base_ptr is 64 bytes, so a guest
> > under a vSMMU might pass a pointer that's not aligned on 4k.
> >   
> PASID table pointer for VT-d is 4K aligned. 
> > Maybe this information could be part of the data passed to userspace
> > about IOMMU table formats and features? They're not part of this
> > series, but I think we wanted to communicate IOMMU-specific features
> > via sysfs.
> >   
> Agreed, I believe Yi Liu is working on a sysfs interface such that QEMU
> can match IOMMU model and features.

Digging this up again since v5 still has this issue.  The IOMMU API is
a kernel internal abstraction of the IOMMU.  sysfs is a userspace
interface.  Are we suggesting that the /only/ way to make use of the
internal IOMMU API here is to have a user provided opaque pasid table
that we can't even do minimal compatibility sanity testing on and we
simply hope that hardware covers all the fault conditions without
taking the host down with it?  I guess we have to assume the latter
since the user has full control of the table, but I have a hard time
getting past lack of internal ability to use the interface and no
ability to provide even the slimmest sanity testing.  Thanks,

Alex

  reply	other threads:[~2018-05-29 20:09 UTC|newest]

Thread overview: 69+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-16 21:48 [PATCH v4 00/22] IOMMU and VT-d driver support for Shared Virtual Address (SVA) Jacob Pan
2018-04-16 21:48 ` [PATCH v4 01/22] iommu: introduce bind_pasid_table API function Jacob Pan
2018-04-16 21:48 ` [PATCH v4 02/22] iommu/vt-d: move device_domain_info to header Jacob Pan
2018-04-16 21:48 ` [PATCH v4 03/22] iommu/vt-d: add a flag for pasid table bound status Jacob Pan
2018-04-16 21:48 ` [PATCH v4 04/22] iommu/vt-d: add bind_pasid_table function Jacob Pan
2018-04-17 19:10   ` Alex Williamson
2018-04-20 18:25     ` Jean-Philippe Brucker
2018-04-20 23:42       ` Jacob Pan
2018-05-29 20:09         ` Alex Williamson [this message]
2018-05-30  1:41           ` Tian, Kevin
2018-05-30  3:17             ` Alex Williamson
2018-05-30  3:45               ` Tian, Kevin
2018-05-30 11:53                 ` Jean-Philippe Brucker
2018-05-30 19:52                   ` Jacob Pan
2018-05-31  9:09                     ` Jean-Philippe Brucker
2018-06-05 17:32                       ` Jacob Pan
2018-06-06 11:20                         ` Jean-Philippe Brucker
2018-06-06 21:22                           ` Jacob Pan
2018-06-07 13:21                             ` Jean-Philippe Brucker
2018-04-20 23:22     ` Jacob Pan
2018-04-16 21:48 ` [PATCH v4 05/22] iommu: introduce iommu invalidate API function Jacob Pan
2018-04-20 18:19   ` Jean-Philippe Brucker
2018-04-23 20:43     ` Jacob Pan
2018-04-27 18:07       ` Jean-Philippe Brucker
2018-04-28  2:41         ` Tian, Kevin
2018-05-01 22:58         ` Jacob Pan
2018-05-02  9:31           ` Jean-Philippe Brucker
2018-05-04  4:46             ` Jacob Pan
2018-05-04 18:07               ` Jacob Pan
2018-05-08 10:35                 ` Jean-Philippe Brucker
2018-05-09 12:55                   ` Jacob Pan
2018-05-05 22:19   ` Jerry Snitselaar
2018-05-07 15:41     ` Jacob Pan
2018-04-16 21:48 ` [PATCH v4 06/22] iommu/vt-d: add definitions for PFSID Jacob Pan
2018-04-16 21:48 ` [PATCH v4 07/22] iommu/vt-d: fix dev iotlb pfsid use Jacob Pan
2018-04-16 21:48 ` [PATCH v4 08/22] iommu/vt-d: support flushing more translation cache types Jacob Pan
2018-04-16 21:48 ` [PATCH v4 09/22] iommu/vt-d: add svm/sva invalidate function Jacob Pan
2018-04-17 19:10   ` Alex Williamson
2018-04-20 22:36     ` Jacob Pan
2018-04-16 21:48 ` [PATCH v4 10/22] iommu: introduce device fault data Jacob Pan
2018-04-23 10:11   ` Jean-Philippe Brucker
2018-04-23 11:54     ` Jacob Pan
2018-05-20  8:17   ` Liu, Yi L
2018-05-21 23:16     ` Jacob Pan
2018-04-16 21:49 ` [PATCH v4 11/22] driver core: add per device iommu param Jacob Pan
2018-04-23 10:26   ` Greg Kroah-Hartman
2018-04-16 21:49 ` [PATCH v4 12/22] iommu: introduce device fault report API Jacob Pan
2018-04-23 11:30   ` Jean-Philippe Brucker
2018-04-24 18:29     ` Jacob Pan
2018-04-30 16:53   ` Jean-Philippe Brucker
2018-04-30 18:54     ` Jacob Pan
2018-04-16 21:49 ` [PATCH v4 13/22] iommu: introduce page response function Jacob Pan
2018-04-23 11:47   ` Jean-Philippe Brucker
2018-04-23 12:16     ` Jacob Pan
2018-04-23 15:50       ` Jean-Philippe Brucker
2018-04-16 21:49 ` [PATCH v4 14/22] iommu: handle page response timeout Jacob Pan
2018-04-23 15:36   ` Jean-Philippe Brucker
2018-04-25 15:37     ` Jacob Pan
2018-04-30 10:58       ` Jean-Philippe Brucker
2018-04-30 17:54         ` Jacob Pan
2018-04-16 21:49 ` [PATCH v4 15/22] iommu/config: add build dependency for dmar Jacob Pan
2018-04-16 21:49 ` [PATCH v4 16/22] iommu/vt-d: report non-recoverable faults to device Jacob Pan
2018-04-16 21:49 ` [PATCH v4 17/22] iommu/intel-svm: report device page request Jacob Pan
2018-04-16 21:49 ` [PATCH v4 18/22] iommu/intel-svm: replace dev ops with fault report API Jacob Pan
2018-04-16 21:49 ` [PATCH v4 19/22] iommu/intel-svm: do not flush iotlb for viommu Jacob Pan
2018-04-16 21:49 ` [PATCH v4 20/22] iommu/vt-d: add intel iommu page response function Jacob Pan
2018-04-16 21:49 ` [PATCH v4 21/22] trace/iommu: add sva trace events Jacob Pan
2018-04-16 21:49 ` [PATCH v4 22/22] iommu: use sva invalidate and device fault trace event Jacob Pan
  -- strict thread matches above, loose matches on Subject: below --
2018-03-23  3:11 [PATCH v4 00/22] IOMMU and VT-d driver support for Shared Virtual Address (SVA) Jacob Pan
2018-03-23  3:11 ` [PATCH v4 04/22] iommu/vt-d: add bind_pasid_table function Jacob Pan

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