From: Paul Durrant <Paul.Durrant@citrix.com>
To: 'Jan Beulich' <JBeulich@suse.com>,
Roger Pau Monne <roger.pau@citrix.com>
Cc: Kevin Tian <kevin.tian@intel.com>,
Stefano Stabellini <sstabellini@kernel.org>,
Wei Liu <wei.liu2@citrix.com>,
Andrew Cooper <Andrew.Cooper3@citrix.com>,
"Tim (Xen.org)" <tim@xen.org>,
George Dunlap <George.Dunlap@citrix.com>,
Julien Grall <julien.grall@arm.com>,
xen-devel <xen-devel@lists.xenproject.org>,
Ian Jackson <Ian.Jackson@citrix.com>
Subject: Re: [PATCH 2/4] iommu: generalize iommu_inclusive_mapping
Date: Wed, 1 Aug 2018 08:33:47 +0000 [thread overview]
Message-ID: <49a6843f08e44a738684c954b8318fa2@AMSPEX02CL03.citrite.net> (raw)
In-Reply-To: <5B616D5402000078001D9BFE@prv1-mh.provo.novell.com>
> -----Original Message-----
> From: Xen-devel [mailto:xen-devel-bounces@lists.xenproject.org] On Behalf
> Of Jan Beulich
> Sent: 01 August 2018 09:21
> To: Roger Pau Monne <roger.pau@citrix.com>
> Cc: Kevin Tian <kevin.tian@intel.com>; Stefano Stabellini
> <sstabellini@kernel.org>; Wei Liu <wei.liu2@citrix.com>; George Dunlap
> <George.Dunlap@citrix.com>; Andrew Cooper
> <Andrew.Cooper3@citrix.com>; Ian Jackson <Ian.Jackson@citrix.com>; Tim
> (Xen.org) <tim@xen.org>; Julien Grall <julien.grall@arm.com>; xen-devel
> <xen-devel@lists.xenproject.org>
> Subject: Re: [Xen-devel] [PATCH 2/4] iommu: generalize
> iommu_inclusive_mapping
>
> >>> On 31.07.18 at 17:33, <roger.pau@citrix.com> wrote:
> > On Tue, Jul 31, 2018 at 08:39:22AM -0600, Jan Beulich wrote:
> >> >>> On 27.07.18 at 17:31, <roger.pau@citrix.com> wrote:
> >> > Introduce a new iommu=inclusive generic option that supersedes
> >> > iommu_inclusive_mapping. This should be a non-functional change on
> >> > Intel hardware, while AMD hardware will gain the same functionality of
> >> > mapping almost everything below the 4GB boundary.
> >>
> >> So first of all - what's the motivation behind this change? So far we
> >> had no need for hacks line the VT-d side one on AMD. I don't think
> >> this should be widened without there being indication of a problem
> >> with non-niche AMD systems.
> >
> > OK, I can leave the default on for Intel and off for everything else,
> > but I will introduce the generic dom0-iommu= option anyway.
>
> Hmm, I've always been wishing we'd change to a default of off for
> VT-d as well - imo we shouldn't by default assume broken firmware.
> Kevin?
I suspect that a seriously large number of Xen users will find their systems fail to boot if the default is changed. I'm testing on a Dell R730 with (to my knowledge) up-to-date firmware. Not exactly a rare system and turning off inclusive mapping will cause it to wedge during boot.
Paul
>
> As to AMD - you still don't really say why this would be needed
> there. I'm not in favor of workarounds when there's nothing to
> work around. IOW - if the logic isn't needed on AMD, do we need
> this code movement in the first place?
>
> Jan
>
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xenproject.org
> https://lists.xenproject.org/mailman/listinfo/xen-devel
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next prev parent reply other threads:[~2018-08-01 8:33 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-27 15:31 [PATCH 0/4] x86/iommu: PVH Dom0 workarounds for missing RMRR/IRSV entries Roger Pau Monne
2018-07-27 15:31 ` [PATCH 1/4] iommu: remove unneeded return from iommu_hwdom_init Roger Pau Monne
2018-07-31 7:19 ` Paul Durrant
2018-07-27 15:31 ` [PATCH 2/4] iommu: generalize iommu_inclusive_mapping Roger Pau Monne
2018-07-31 7:18 ` Paul Durrant
2018-07-31 8:16 ` Roger Pau Monné
2018-07-31 8:27 ` Paul Durrant
2018-07-31 8:33 ` Roger Pau Monné
2018-07-31 8:37 ` Paul Durrant
2018-07-31 8:49 ` Jan Beulich
2018-07-31 9:05 ` Roger Pau Monné
2018-07-31 9:14 ` Jan Beulich
2018-07-31 9:34 ` Roger Pau Monné
2018-07-31 9:37 ` Paul Durrant
2018-07-31 9:41 ` Jan Beulich
2018-07-31 9:45 ` Paul Durrant
2018-07-31 8:45 ` Jan Beulich
2018-07-31 14:39 ` Jan Beulich
2018-07-31 15:33 ` Roger Pau Monné
2018-08-01 8:20 ` Jan Beulich
2018-08-01 8:32 ` Andrew Cooper
2018-08-01 9:10 ` Jan Beulich
2018-08-01 9:20 ` Andrew Cooper
2018-08-01 9:59 ` Jan Beulich
2018-08-01 10:25 ` Andrew Cooper
2018-08-01 8:33 ` Paul Durrant [this message]
2018-08-01 9:11 ` Jan Beulich
2018-08-02 6:53 ` Tian, Kevin
2018-08-01 8:47 ` Roger Pau Monné
2018-07-27 15:31 ` [PATCH 3/4] x86/iommu: reorder conditions used in the inclusive iommu mappings Roger Pau Monne
2018-07-31 7:29 ` Paul Durrant
2018-07-31 8:26 ` Roger Pau Monné
2018-07-27 15:31 ` [PATCH 4/4] x86/iommu: add PVH support to the inclusive options Roger Pau Monne
2018-07-31 7:36 ` Paul Durrant
2018-07-31 8:28 ` Roger Pau Monné
2018-07-31 14:52 ` Jan Beulich
2018-07-31 15:15 ` Roger Pau Monné
2018-07-31 15:27 ` Roger Pau Monné
2018-07-31 15:34 ` Jan Beulich
2018-07-31 15:33 ` Jan Beulich
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