linux-kernel - Re: [PATCH 01/26] iommu/vt-d: Keep track of per-iommu domain ids

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Date:	Fri, 7 Aug 2015 13:07:01 +0200
From:	Joerg Roedel <joro@...tes.org>
To:	Alex Williamson <alex.williamson@...hat.com>
Cc:	iommu@...ts.linux-foundation.org,
	David Woodhouse <dwmw2@...radead.org>,
	linux-kernel@...r.kernel.org, jroedel@...e.de
Subject: Re: [PATCH 01/26] iommu/vt-d: Keep track of per-iommu domain ids

On Thu, Aug 06, 2015 at 01:19:52PM -0600, Alex Williamson wrote:
> On Wed, 2015-08-05 at 17:18 +0200, Joerg Roedel wrote:
> > From: Joerg Roedel <jroedel@...e.de>
> > 
> > Instead of searching in the domain array for already
> > allocated domain ids, keep track of them explicitly.
> > 
> > Signed-off-by: Joerg Roedel <jroedel@...e.de>
> > ---
> >  drivers/iommu/intel-iommu.c | 51 +++++++++++++++++++++++----------------------
> >  1 file changed, 26 insertions(+), 25 deletions(-)
> > 
> > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> > index 0649b94..c3c5167 100644
> > --- a/drivers/iommu/intel-iommu.c
> > +++ b/drivers/iommu/intel-iommu.c
> > @@ -378,6 +378,9 @@ struct dmar_domain {
> >  	DECLARE_BITMAP(iommu_bmp, DMAR_UNITS_SUPPORTED);
> >  					/* bitmap of iommus this domain uses*/
> >  
> > +	u16	iommu_did[DMAR_UNITS_SUPPORTED];
> > +					/* Domain ids per IOMMU */
> 
> Maybe a spec reference here to justify u16 that the 2.3 vt-d spec only
> supports up to 16bit domain IDs.

Makes sense, I added a reference to the VT-d spec, section 9.3.

> > +	num = domain->iommu_did[iommu->seq_id];
> > +
> > +	WARN_ON(num == 0);
> 
> Return -ENODEV and let the caller decide if that's an error?  Then we
> could safely call this over all all iommus.

Changed that too, but not -ENODEV but just a plain return. The callers
do not care about errors anyway.


	Joerg

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