On Sat, Nov 27, 2021 at 05:18:28PM +0100, Eric Auger wrote:
> Hi Jean,
>
> On 11/23/21 4:52 PM, Jean-Philippe Brucker wrote:
> > The VIRTIO_IOMMU_F_BYPASS_CONFIG feature adds a new flag to the ATTACH
> > request, that creates a bypass domain. Use it to enable identity
> > domains.
> >
> > When VIRTIO_IOMMU_F_BYPASS_CONFIG is not supported by the device, we
> > currently fail attaching to an identity domain. Future patches will
> > instead create identity mappings in this case.
> >
> > Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
> > Signed-off-by: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>
> > ---
> > drivers/iommu/virtio-iommu.c | 20 +++++++++++++++++++-
> > 1 file changed, 19 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c
> > index 80930ce04a16..ee8a7afd667b 100644
> > --- a/drivers/iommu/virtio-iommu.c
> > +++ b/drivers/iommu/virtio-iommu.c
> > @@ -71,6 +71,7 @@ struct viommu_domain {
> > struct rb_root_cached mappings;
> >
> > unsigned long nr_endpoints;
> > + bool bypass;
> > };
> >
> > struct viommu_endpoint {
> > @@ -587,7 +588,9 @@ static struct iommu_domain *viommu_domain_alloc(unsigned type)
> > {
> > struct viommu_domain *vdomain;
> >
> > - if (type != IOMMU_DOMAIN_UNMANAGED && type != IOMMU_DOMAIN_DMA)
> > + if (type != IOMMU_DOMAIN_UNMANAGED &&
> > + type != IOMMU_DOMAIN_DMA &&
> > + type != IOMMU_DOMAIN_IDENTITY)
> > return NULL;
> >
> > vdomain = kzalloc(sizeof(*vdomain), GFP_KERNEL);
> > @@ -630,6 +633,17 @@ static int viommu_domain_finalise(struct viommu_endpoint *vdev,
> > vdomain->map_flags = viommu->map_flags;
> > vdomain->viommu = viommu;
> >
> > + if (domain->type == IOMMU_DOMAIN_IDENTITY) {
> > + if (!virtio_has_feature(viommu->vdev,
> nit: couldn't the check be done before the ida_alloc_range(),
> simplifying the failure cleanup?
It could, but patch 5 falls back to identity mappings, which is better
left at the end of the function to keep the error path simple. I put this
at the end already here, so patch 5 doesn't need to move things around.
Thanks,
Jean
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