From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: Kevin Tian <kevin.tian@intel.com>,
Stefano Stabellini <sstabellini@kernel.org>,
Wei Liu <wei.liu2@citrix.com>,
George Dunlap <George.Dunlap@eu.citrix.com>,
Ian Jackson <Ian.Jackson@eu.citrix.com>, Tim Deegan <tim@xen.org>,
Julien Grall <julien.grall@arm.com>,
xen-devel <xen-devel@lists.xenproject.org>,
Roger Pau Monne <roger.pau@citrix.com>
Subject: Re: [PATCH 2/4] iommu: generalize iommu_inclusive_mapping
Date: Wed, 1 Aug 2018 10:20:41 +0100 [thread overview]
Message-ID: <6654f71d-935d-b560-db7f-e2f65f20bcf5@citrix.com> (raw)
In-Reply-To: <5B61791802000078001D9C8B@prv1-mh.provo.novell.com>
On 01/08/2018 10:10, Jan Beulich wrote:
>> Furthermore, on by default is the only reasonable option. Dom0 is
>> specifically given cpu mappings of the reserved regions, therefore it
>> should have matching IOMMU mappings.
> I don't think I can uniformly agree with this: There are reserved
> regions which specifically would better not have IOMMU mappings:
> LAPIC, IO-APIC, MMCFG just to name things I can immediately
> think of.
Right, but that's not what I said.
For any CPU mapping, we should have a matching IOMMU mapping. This is
how hardware behaves in a native system, and is how all operating
systems are written to behave. Breaking this expectation will break
software in unexpected ways.
For the items you list there, we don't give dom0 CPU mappings (because
restricting them is indeed a sensible thing), and the "matching" mapping
in the IOMMU is also not present.
~Andrew
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next prev parent reply other threads:[~2018-08-01 9:20 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 [this message]
2018-08-01 9:59 ` Jan Beulich
2018-08-01 10:25 ` Andrew Cooper
2018-08-01 8:33 ` Paul Durrant
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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