From: Paul Durrant <Paul.Durrant@citrix.com>
To: 'Jan Beulich' <JBeulich@suse.com>
Cc: Andrew Cooper <Andrew.Cooper3@citrix.com>,
xen-devel <xen-devel@lists.xenproject.org>,
Wei Liu <wei.liu2@citrix.com>,
George Dunlap <George.Dunlap@citrix.com>,
Roger Pau Monne <roger.pau@citrix.com>
Subject: Re: [PATCH v2 4/4] x86/mm/p2m: stop checking for IOMMU shared page tables in mmio_order()
Date: Tue, 4 Dec 2018 15:22:34 +0000 [thread overview]
Message-ID: <dd9518307f2140d7bbae1ebd531d471e@AMSPEX02CL03.citrite.net> (raw)
In-Reply-To: <5C069B450200007800202C22@prv1-mh.provo.novell.com>
> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@suse.com]
> Sent: 04 December 2018 15:21
> To: Paul Durrant <Paul.Durrant@citrix.com>
> Cc: Andrew Cooper <Andrew.Cooper3@citrix.com>; Roger Pau Monne
> <roger.pau@citrix.com>; Wei Liu <wei.liu2@citrix.com>; George Dunlap
> <George.Dunlap@citrix.com>; xen-devel <xen-devel@lists.xenproject.org>
> Subject: Re: [PATCH v2 4/4] x86/mm/p2m: stop checking for IOMMU shared
> page tables in mmio_order()
>
> >>> On 03.12.18 at 18:40, <paul.durrant@citrix.com> wrote:
> > Now that the iommu_map() and iommu_unmap() operations take an order
> > parameter and elide flushing there's no strong reason why modifying MMIO
> > ranges in the p2m should be restricted to a 4k granularity simply
> because
> > the IOMMU is enabled but shared page tables are not in operation.
>
> I'm afraid the two improvements are not enough for this restriction
> to be lifted: There's still no preemption in the processing of the
> higher order values.
Why? 1G orders are already ruled out and testing shows that 2M orders cause no problems on EPYC systems.
Paul
>
> Jan
>
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next prev parent reply other threads:[~2018-12-04 15:28 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-03 17:40 [PATCH v2 0/4] iommu improvements Paul Durrant
2018-12-03 17:40 ` [PATCH v2 1/4] amd-iommu: add flush iommu_ops Paul Durrant
2018-12-04 14:24 ` Jan Beulich
2018-12-04 14:56 ` Paul Durrant
2018-12-03 17:40 ` [PATCH v2 2/4] iommu: rename wrapper functions Paul Durrant
2018-12-04 14:51 ` Jan Beulich
2018-12-04 15:00 ` Paul Durrant
2018-12-03 17:40 ` [PATCH v2 3/4] iommu: elide flushing for higher order map/unmap operations Paul Durrant
2018-12-04 15:16 ` Jan Beulich
2018-12-04 15:36 ` Paul Durrant
2018-12-04 16:01 ` Jan Beulich
2018-12-04 16:53 ` Paul Durrant
2018-12-04 17:20 ` Jan Beulich
2018-12-03 17:40 ` [PATCH v2 4/4] x86/mm/p2m: stop checking for IOMMU shared page tables in mmio_order() Paul Durrant
2018-12-04 15:20 ` Jan Beulich
2018-12-04 15:22 ` Paul Durrant [this message]
2018-12-04 15:36 ` Jan Beulich
2018-12-04 15:51 ` Jan Beulich
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