linux-kernel - RE: [PATCH v7 2/6] vfio/type1: Check reserve region conflict and update iova list

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Message-ID: <5FC3163CFD30C246ABAA99954A238FA83F2DDB68@lhreml524-mbs.china.huawei.com>
Date:   Thu, 4 Jul 2019 12:51:13 +0000
From:   Shameerali Kolothum Thodi <shameerali.kolothum.thodi@...wei.com>
To:     Alex Williamson <alex.williamson@...hat.com>
CC:     "eric.auger@...hat.com" <eric.auger@...hat.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        Linuxarm <linuxarm@...wei.com>,
        "John Garry" <john.garry@...wei.com>,
        "xuwei (O)" <xuwei5@...wei.com>,
        "kevin.tian@...el.com" <kevin.tian@...el.com>
Subject: RE: [PATCH v7 2/6] vfio/type1: Check reserve region conflict and
 update iova list



> -----Original Message-----
> From: kvm-owner@...r.kernel.org [mailto:kvm-owner@...r.kernel.org] On
> Behalf Of Alex Williamson
> Sent: 03 July 2019 21:34
> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@...wei.com>
> Cc: eric.auger@...hat.com; pmorel@...ux.vnet.ibm.com;
> kvm@...r.kernel.org; linux-kernel@...r.kernel.org;
> iommu@...ts.linux-foundation.org; Linuxarm <linuxarm@...wei.com>; John
> Garry <john.garry@...wei.com>; xuwei (O) <xuwei5@...wei.com>;
> kevin.tian@...el.com
> Subject: Re: [PATCH v7 2/6] vfio/type1: Check reserve region conflict and
> update iova list
> 
> On Wed, 26 Jun 2019 16:12:44 +0100
> Shameer Kolothum <shameerali.kolothum.thodi@...wei.com> wrote:
> 
> > This retrieves the reserved regions associated with dev group and
> > checks for conflicts with any existing dma mappings. Also update
> > the iova list excluding the reserved regions.
> >
> > Reserved regions with type IOMMU_RESV_DIRECT_RELAXABLE are
> > excluded from above checks as they are considered as directly
> > mapped regions which are known to be relaxable.
> >
> > Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>
> > ---
> >  drivers/vfio/vfio_iommu_type1.c | 96
> +++++++++++++++++++++++++++++++++
> >  1 file changed, 96 insertions(+)
> >
> > diff --git a/drivers/vfio/vfio_iommu_type1.c
> b/drivers/vfio/vfio_iommu_type1.c
> > index 970d1ec06aed..b6bfdfa16c33 100644
> > --- a/drivers/vfio/vfio_iommu_type1.c
> > +++ b/drivers/vfio/vfio_iommu_type1.c
> > @@ -1559,6 +1641,7 @@ static int vfio_iommu_type1_attach_group(void
> *iommu_data,
> >  	phys_addr_t resv_msi_base;
> >  	struct iommu_domain_geometry geo;
> >  	LIST_HEAD(iova_copy);
> > +	LIST_HEAD(group_resv_regions);
> >
> >  	mutex_lock(&iommu->lock);
> >
> > @@ -1644,6 +1727,13 @@ static int vfio_iommu_type1_attach_group(void
> *iommu_data,
> >  		goto out_detach;
> >  	}
> >
> > +	iommu_get_group_resv_regions(iommu_group, &group_resv_regions);
> 
> This can fail and should have an error case.  I assume we'd fail the
> group attach on failure.  Thanks,

Right. I will add the check. Do you think we should do the same in vfio_iommu_has_sw_msi()
as well? (In fact, it looks like iommu_get_group_resv_regions() ret is not checked anywhere in
kernel). 

Thanks,
Shameer