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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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