linux-kernel - RE: [PATCH v5 03/15] iommu/smmu: Report empty domain nesting info

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Date:   Mon, 20 Jul 2020 07:26:05 +0000
From:   "Liu, Yi L" <yi.l.liu@...el.com>
To:     Auger Eric <eric.auger@...hat.com>,
        "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
        "baolu.lu@...ux.intel.com" <baolu.lu@...ux.intel.com>,
        "joro@...tes.org" <joro@...tes.org>
CC:     "Tian, Kevin" <kevin.tian@...el.com>,
        "jacob.jun.pan@...ux.intel.com" <jacob.jun.pan@...ux.intel.com>,
        "Raj, Ashok" <ashok.raj@...el.com>,
        "Tian, Jun J" <jun.j.tian@...el.com>,
        "Sun, Yi Y" <yi.y.sun@...el.com>,
        "jean-philippe@...aro.org" <jean-philippe@...aro.org>,
        "peterx@...hat.com" <peterx@...hat.com>,
        "Wu, Hao" <hao.wu@...el.com>,
        "stefanha@...il.com" <stefanha@...il.com>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>
Subject: RE: [PATCH v5 03/15] iommu/smmu: Report empty domain nesting info

Hi Eric,

> From: Auger Eric <eric.auger@...hat.com>
> 
> Yi,
> 
> On 7/12/20 1:20 PM, Liu Yi L wrote:
> > This patch is added as instead of returning a boolean for
> > DOMAIN_ATTR_NESTING,
> > iommu_domain_get_attr() should return an iommu_nesting_info handle.
> 
> you may add in the commit message you return an empty nesting info struct for now
> as true nesting is not yet supported by the SMMUs.

will do.

> Besides:
> Reviewed-by: Eric Auger <eric.auger@...hat.com>

thanks.

Regards,
Yi Liu

> Thanks
> 
> Eric
> >
> > Cc: Will Deacon <will@...nel.org>
> > Cc: Robin Murphy <robin.murphy@....com>
> > Cc: Eric Auger <eric.auger@...hat.com>
> > Cc: Jean-Philippe Brucker <jean-philippe@...aro.org>
> > Suggested-by: Jean-Philippe Brucker <jean-philippe@...aro.org>
> > Signed-off-by: Liu Yi L <yi.l.liu@...el.com>
> > Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> > ---
> > v4 -> v5:
> > *) address comments from Eric Auger.
> > ---
> >  drivers/iommu/arm-smmu-v3.c | 29 +++++++++++++++++++++++++++--
> >  drivers/iommu/arm-smmu.c    | 29 +++++++++++++++++++++++++++--
> >  2 files changed, 54 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
> > index f578677..ec815d7 100644
> > --- a/drivers/iommu/arm-smmu-v3.c
> > +++ b/drivers/iommu/arm-smmu-v3.c
> > @@ -3019,6 +3019,32 @@ static struct iommu_group
> *arm_smmu_device_group(struct device *dev)
> >  	return group;
> >  }
> >
> > +static int arm_smmu_domain_nesting_info(struct arm_smmu_domain
> *smmu_domain,
> > +					void *data)
> > +{
> > +	struct iommu_nesting_info *info = (struct iommu_nesting_info *)data;
> > +	unsigned int size;
> > +
> > +	if (!info || smmu_domain->stage != ARM_SMMU_DOMAIN_NESTED)
> > +		return -ENODEV;
> > +
> > +	size = sizeof(struct iommu_nesting_info);
> > +
> > +	/*
> > +	 * if provided buffer size is smaller than expected, should
> > +	 * return 0 and also the expected buffer size to caller.
> > +	 */
> > +	if (info->size < size) {
> > +		info->size = size;
> > +		return 0;
> > +	}
> > +
> > +	/* report an empty iommu_nesting_info for now */
> > +	memset(info, 0x0, size);
> > +	info->size = size;
> > +	return 0;
> > +}
> > +
> >  static int arm_smmu_domain_get_attr(struct iommu_domain *domain,
> >  				    enum iommu_attr attr, void *data)  { @@ -
> 3028,8 +3054,7 @@
> > static int arm_smmu_domain_get_attr(struct iommu_domain *domain,
> >  	case IOMMU_DOMAIN_UNMANAGED:
> >  		switch (attr) {
> >  		case DOMAIN_ATTR_NESTING:
> > -			*(int *)data = (smmu_domain->stage ==
> ARM_SMMU_DOMAIN_NESTED);
> > -			return 0;
> > +			return arm_smmu_domain_nesting_info(smmu_domain,
> data);
> >  		default:
> >  			return -ENODEV;
> >  		}
> > diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c index
> > 243bc4c..09e2f1b 100644
> > --- a/drivers/iommu/arm-smmu.c
> > +++ b/drivers/iommu/arm-smmu.c
> > @@ -1506,6 +1506,32 @@ static struct iommu_group
> *arm_smmu_device_group(struct device *dev)
> >  	return group;
> >  }
> >
> > +static int arm_smmu_domain_nesting_info(struct arm_smmu_domain
> *smmu_domain,
> > +					void *data)
> > +{
> > +	struct iommu_nesting_info *info = (struct iommu_nesting_info *)data;
> > +	unsigned int size;
> > +
> > +	if (!info || smmu_domain->stage != ARM_SMMU_DOMAIN_NESTED)
> > +		return -ENODEV;
> > +
> > +	size = sizeof(struct iommu_nesting_info);
> > +
> > +	/*
> > +	 * if provided buffer size is smaller than expected, should
> > +	 * return 0 and also the expected buffer size to caller.
> > +	 */
> > +	if (info->size < size) {
> > +		info->size = size;
> > +		return 0;
> > +	}
> > +
> > +	/* report an empty iommu_nesting_info for now */
> > +	memset(info, 0x0, size);
> > +	info->size = size;
> > +	return 0;
> > +}
> > +
> >  static int arm_smmu_domain_get_attr(struct iommu_domain *domain,
> >  				    enum iommu_attr attr, void *data)  { @@ -
> 1515,8 +1541,7 @@
> > static int arm_smmu_domain_get_attr(struct iommu_domain *domain,
> >  	case IOMMU_DOMAIN_UNMANAGED:
> >  		switch (attr) {
> >  		case DOMAIN_ATTR_NESTING:
> > -			*(int *)data = (smmu_domain->stage ==
> ARM_SMMU_DOMAIN_NESTED);
> > -			return 0;
> > +			return arm_smmu_domain_nesting_info(smmu_domain,
> data);
> >  		default:
> >  			return -ENODEV;
> >  		}
> >