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    SubjectRe: [PATCH 06/22] iommu: Allocate a default domain for iommu groups
    Hi Joerg,

    On 28/05/15 17:41, Joerg Roedel wrote:
    > From: Joerg Roedel <jroedel@suse.de>
    >
    > The default domain will be used (if supported by the iommu
    > driver) when the devices in the iommu group are not attached
    > to any other domain.
    >
    > Signed-off-by: Joerg Roedel <jroedel@suse.de>
    > ---
    > drivers/iommu/iommu.c | 32 ++++++++++++++++++++++++++++----
    > 1 file changed, 28 insertions(+), 4 deletions(-)
    >
    > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
    > index d69e0ca..fbfc015 100644
    > --- a/drivers/iommu/iommu.c
    > +++ b/drivers/iommu/iommu.c
    > @@ -51,6 +51,7 @@ struct iommu_group {
    > void (*iommu_data_release)(void *iommu_data);
    > char *name;
    > int id;
    > + struct iommu_domain *default_domain;
    > };
    >
    > struct iommu_device {
    > @@ -75,6 +76,9 @@ struct iommu_group_attribute iommu_group_attr_##_name = \
    > #define to_iommu_group(_kobj) \
    > container_of(_kobj, struct iommu_group, kobj)
    >
    > +static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus,
    > + unsigned type);
    > +
    > static ssize_t iommu_group_attr_show(struct kobject *kobj,
    > struct attribute *__attr, char *buf)
    > {
    > @@ -137,6 +141,9 @@ static void iommu_group_release(struct kobject *kobj)
    > ida_remove(&iommu_group_ida, group->id);
    > mutex_unlock(&iommu_group_mutex);
    >
    > + if (group->default_domain)
    > + iommu_domain_free(group->default_domain);
    > +
    > kfree(group->name);
    > kfree(group);
    > }
    > @@ -701,7 +708,18 @@ static struct iommu_group *iommu_group_get_for_pci_dev(struct pci_dev *pdev)
    > return group;
    >
    > /* No shared group found, allocate new */
    > - return iommu_group_alloc();
    > + group = iommu_group_alloc();
    > + if (group) {
    > + /*
    > + * Try to allocate a default domain - needs support from the
    > + * IOMMU driver.
    > + */
    > + group->default_domain = __iommu_domain_alloc(pdev->dev.bus,
    > + IOMMU_DOMAIN_DMA);
    > + group->domain = group->default_domain;
    > + }
    > +
    > + return group;
    > }
    >
    > /**
    > @@ -922,22 +940,28 @@ void iommu_set_fault_handler(struct iommu_domain *domain,
    > }
    > EXPORT_SYMBOL_GPL(iommu_set_fault_handler);
    >
    > -struct iommu_domain *iommu_domain_alloc(struct bus_type *bus)
    > +static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus,
    > + unsigned type)

    I'd be happier if we passed the iommu_ops in here...

    > {
    > struct iommu_domain *domain;
    >
    > if (bus == NULL || bus->iommu_ops == NULL)
    > return NULL;
    >
    > - domain = bus->iommu_ops->domain_alloc(IOMMU_DOMAIN_UNMANAGED);
    > + domain = bus->iommu_ops->domain_alloc(type);
    > if (!domain)
    > return NULL;
    >
    > domain->ops = bus->iommu_ops;
    > - domain->type = IOMMU_DOMAIN_UNMANAGED;
    > + domain->type = type;
    >
    > return domain;
    > }
    > +
    > +struct iommu_domain *iommu_domain_alloc(struct bus_type *bus)
    > +{

    ..having pulled them out of the bus here.

    > + return __iommu_domain_alloc(bus, IOMMU_DOMAIN_UNMANAGED);
    > +}
    > EXPORT_SYMBOL_GPL(iommu_domain_alloc);
    >
    > void iommu_domain_free(struct iommu_domain *domain)
    >

    Even if it's only to symbolically inch us closer to having some other
    solution for platform bus devices. The SMMU page size debate is one
    thing, but it's really only a subtle case of the "IOMMU instances"
    problem. Once there are two different IOMMU drivers in the system each
    serving a subset of platform devices, how can we make sure the domain
    allocated here is wrapped in the right driver-private struct? I've had a
    try with making iommu_ops per-instance, but even that doesn't work in
    this case.

    Robin.



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