[Xen-devel] RE: [PATCH] re-enable HVM PCI passthrough functionality

["Kay, Allen M" <allen.m.kay@xxxxxxxxx>]

I have updated the patch to indicate valid_mfn() cannot be used here as MMIO 
pages are always above max_mem.  Also added sanity checking for type == 
p2m_mmio_direct before clearing page table entry.  This should fix both VT-d 
and SR-IOV issues reported recently as there are no SR-IOV specific code in 
Xen.  As far as Xen is concern, SR-IOV virtual function is just another PCI 
device.

Signed-off-by: Allen Kay allen.m.kay@xxxxxxxxx

-----Original Message-----
From: Christoph Egger [mailto:Christoph.Egger@xxxxxxx] 
Sent: Tuesday, August 31, 2010 2:35 AM
To: Tim Deegan
Cc: Kay, Allen M; xen-devel@xxxxxxxxxxxxxxxxxxx; Keir Fraser
Subject: Re: [PATCH] re-enable HVM PCI passthrough functionality

On Tuesday 31 August 2010 11:17:27 Tim Deegan wrote:
> At 02:58 +0100 on 31 Aug (1283223494), Kay, Allen M wrote:
> > Attached patch reverts back to INVALID_MFN.  PCI passthrough
> > functionality works with this patch.
>
> Apologies for missing this - I did ask for this enormous patch to
> contain only what it said on the tin (and I did read it to check!) but
> this one got through.

Also apologies from my side. I did what Tim requested for, but that
one slipped through.

> > Signed-off-by: Allen Kay allen.m.kay@xxxxxxxxx
>
> This is fine, but please add a comment explaining the rather subtle use
> of INVALID_MFN here so the next tidy-minded person doesn't "fix" it
> again. :)
>
> In fact would it be better to check the returned type == p2m_mmio_direct
> instead?  That seems like it would fit better with the intention.   Or
> do other callers use this to clean non-mmio entries too?

I'm interested in if this patch fixes the SR-IOV issue. We are still about
investigation...

Christoph



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Attachment: mm.patch
Description: mm.patch

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