Hi Alex,
On Wed, Sep 24, 2014 at 07:23:19PM +0100, Alex Williamson wrote:
> On Wed, 2014-09-24 at 10:21 +0100, Will Deacon wrote:
> > VFIO allows devices to be safely handed off to userspace by putting
> > them behind an IOMMU configured to ensure DMA and interrupt isolation.
> > This enables userspace KVM clients, such as kvmtool and qemu, to further
> > map the device into a virtual machine.
> >
> > With IOMMUs such as the ARM SMMU, it is then possible to provide SMMU
> > translation services to the guest operating system, which are nested
> > with the existing translation installed by VFIO. However, enabling this
> > feature means that the IOMMU driver must be informed that the VFIO domain
> > is being created for the purposes of nested translation.
> >
> > This patch adds a new IOMMU type (VFIO_TYPE1_NESTING_IOMMU) to the VFIO
> > type-1 driver. The new IOMMU type acts identically to the
> > VFIO_TYPE1v2_IOMMU type, but additionally sets the DOMAIN_ATTR_NESTING
> > attribute on its IOMMU domains.
[...]
> > diff --git a/drivers/vfio/vfio_iommu_type1.c
> > b/drivers/vfio/vfio_iommu_type1.c
> > index 0734fbe5b651..d15b00700a31 100644
> > --- a/drivers/vfio/vfio_iommu_type1.c
> > +++ b/drivers/vfio/vfio_iommu_type1.c
> > @@ -57,7 +57,8 @@ struct vfio_iommu {
> > struct list_head domain_list;
> > struct mutex lock;
> > struct rb_root dma_list;
> > - bool v2;
> > + bool v2;
> > + bool nesting;
> > };
> >
> > struct vfio_domain {
> > @@ -671,7 +672,7 @@ static int vfio_iommu_type1_attach_group(void
> > *iommu_data,
> > struct vfio_group *group, *g;
> > struct vfio_domain *domain, *d;
> > struct bus_type *bus = NULL;
> > - int ret;
> > + int ret, attr = 1;
> >
> > mutex_lock(&iommu->lock);
> >
> > @@ -705,6 +706,13 @@ static int vfio_iommu_type1_attach_group(void
> > *iommu_data,
> > goto out_free;
> > }
> >
> > + if (iommu->nesting) {
>
> nit, attr declaration could be moved here
Sure.
> > + ret = iommu_domain_set_attr(domain->domain, DOMAIN_ATTR_NESTING,
> > + &attr);
> > + if (ret)
> > + goto out_domain;
> > + }
> > +
> > ret = iommu_attach_group(domain->domain, iommu_group);
> > if (ret)
> > goto out_domain;
> > @@ -819,17 +827,25 @@ static void *vfio_iommu_type1_open(unsigned long arg)
> > {
> > struct vfio_iommu *iommu;
> >
> > - if (arg != VFIO_TYPE1_IOMMU && arg != VFIO_TYPE1v2_IOMMU)
> > - return ERR_PTR(-EINVAL);
> > -
> > iommu = kzalloc(sizeof(*iommu), GFP_KERNEL);
> > if (!iommu)
> > return ERR_PTR(-ENOMEM);
> >
> > + switch (arg) {
> > + case VFIO_TYPE1_IOMMU:
> > + break;
> > + case VFIO_TYPE1_NESTING_IOMMU:
> > + iommu->nesting = true;
> > + case VFIO_TYPE1v2_IOMMU:
> > + iommu->v2 = true;
> > + break;
> > + default:
>
> Leaks iommu
Yikes, sorry about that. Will fix.
Will
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