Re: [Qemu-devel] [RFC v1 0/3] intel_iommu: support scalable mode

[Yi Sun]

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