Re: [Xen-devel] [PATCH 0/3] iommu: Introduce range operation

To:	Jean Guyader <jean.guyader@xxxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject:	Re: [Xen-devel] [PATCH 0/3] iommu: Introduce range operation
From:	Keir Fraser <keir@xxxxxxx>
Date:	Thu, 18 Nov 2010 12:36:41 +0000
Cc:	"Kay, Allen M" <allen.m.kay@xxxxxxxxx>
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On 15/11/2010 17:59, "Jean Guyader" <jean.guyader@xxxxxxxxxxxxx> wrote:

> Hi,
> 
> This patches series add a range operation for the intel iommu.
> 
> IOTLBs flushes can be really expensive on some hardware, so we
> need a range interface to only do the flush once, instead of for
> each pages.

I'm going to have a go at TLB flush batching for IOMMUs by extending the
existing TLB clock algorithm. Hopefully it will avoid need for guest
interface changes.

The tradeoff will be that flushes, when they happen, will be full address
space rather than a range flush. But there should be vastly fewer of them.
Nonetheless I may make old vs new flush behaviour switchable via a boot
parameter for a while.

 -- Keir

> 01: intel_iommu_set_entry
> 02: iommu_export_set_entry
> 03: xc_iommu_map_batch
> 
> Thanks,
> Jean
> 
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Re: [Xen-devel] [PATCH 0/3] iommu: Introduce range operation