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Re: [Qemu-devel] [RFC v1 0/3] intel_iommu: support scalable mode
From: |
Yi Sun |
Subject: |
Re: [Qemu-devel] [RFC v1 0/3] intel_iommu: support scalable mode |
Date: |
Wed, 13 Feb 2019 13:46:28 +0800 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On 19-02-11 18:37:41, Peter Xu wrote:
> On Wed, Jan 30, 2019 at 01:09:10PM +0800, Yi Sun wrote:
> > Intel vt-d rev3.0 [1] introduces a new translation mode called
> > 'scalable mode', which enables PASID-granular translations for
> > first level, second level, nested and pass-through modes. The
> > vt-d scalable mode is the key ingredient to enable Scalable I/O
> > Virtualization (Scalable IOV) [2] [3], which allows sharing a
> > device in minimal possible granularity (ADI - Assignable Device
> > Interface). As a result, previous Extended Context (ECS) mode
> > is deprecated (no production ever implements ECS).
> >
> > This patch set emulates a minimal capability set of VT-d scalable
> > mode, equivalent to what is available in VT-d legacy mode today:
> > 1. Scalable mode root entry, context entry and PASID table
> > 2. Seconds level translation under scalable mode
> > 3. Queued invalidation (with 256 bits descriptor)
> > 4. Pass-through mode
> >
> > Corresponding intel-iommu driver support will be included in
> > kernel 5.0:
> > https://www.spinics.net/lists/kernel/msg2985279.html
> >
> > We will add emulation of full scalable mode capability along with
> > guest iommu driver progress later, e.g.:
> > 1. First level translation
> > 2. Nested translation
> > 3. Per-PASID invalidation descriptors
> > 4. Page request services for handling recoverable faults
>
> Hi, YiSun/YiLiu,
>
> Have you tested against any existing usages of VT-d with this series
> applied?
>
Thanks for the review!
With kernel/qemu scalable mode enabling patch sets applied, I tested
kernel build/data copy/netperf on guest under both "scalable-mode"
enabled and "scalable-mode" disabled scenarios.
> Thanks,
>
> --
> Peter Xu