On Thu, Jul 14, 2022 at 06:18:22PM +1000, Alexey Kardashevskiy wrote:
> +/*
> + * A simple iommu_ops to allow less cruft in generic VFIO code.
> + */
> +static bool spapr_tce_iommu_capable(enum iommu_cap cap)
> +{
> + switch (cap) {
> + case IOMMU_CAP_CACHE_COHERENCY:
I would add a remark here that it is because vfio is going to use
SPAPR mode but still checks that the iommu driver support coherency -
with out that detail it looks very strange to have caps without
implementing unmanaged domains
> +static struct iommu_domain *spapr_tce_iommu_domain_alloc(unsigned int type)
> +{
> + struct iommu_domain *dom;
> +
> + if (type != IOMMU_DOMAIN_BLOCKED)
> + return NULL;
> +
> + dom = kzalloc(sizeof(*dom), GFP_KERNEL);
> + if (!dom)
> + return NULL;
> +
> + dom->geometry.aperture_start = 0;
> + dom->geometry.aperture_end = ~0ULL;
> + dom->geometry.force_aperture = true;
A blocked domain doesn't really have an aperture, all DMA is rejected,
so I think these can just be deleted and left at zero.
Generally I'm suggesting drivers just use a static singleton instance
for the blocked domain instead of the allocation like this, but that
is a very minor nit.
> +static struct iommu_device *spapr_tce_iommu_probe_device(struct device *dev)
> +{
> + struct pci_dev *pdev;
> + struct pci_controller *hose;
> +
> + /* Weirdly iommu_device_register() assigns the same ops to all buses */
> + if (!dev_is_pci(dev))
> + return ERR_PTR(-EPERM);
Less "weirdly", more by design. The iommu driver should check if the
given struct device is supported or not, it isn't really a bus
specific operation.
> +static struct iommu_group *spapr_tce_iommu_device_group(struct device *dev)
> +{
> + struct pci_controller *hose;
> + struct pci_dev *pdev;
> +
> + /* Weirdly iommu_device_register() assigns the same ops to all buses */
> + if (!dev_is_pci(dev))
> + return ERR_PTR(-EPERM);
This doesn't need repeating, if probe_device() fails then this will
never be called.
> +static int spapr_tce_iommu_attach_dev(struct iommu_domain *dom,
> + struct device *dev)
> +{
> + struct iommu_group *grp = iommu_group_get(dev);
> + struct iommu_table_group *table_group;
> + int ret = -EINVAL;
> +
> + if (!grp)
> + return -ENODEV;
> +
> + table_group = iommu_group_get_iommudata(grp);
> +
> + if (dom->type == IOMMU_DOMAIN_BLOCKED)
> + ret = table_group->ops->take_ownership(table_group);
Ideally there shouldn't be dom->type checks like this.
The blocking domain should have its own iommu_domain_ops that only
process the blocking operation. Ie call this like
spapr_tce_iommu_blocking_attach_dev()
Instead of having a "default_domain_ops" leave it NULL and create a
spapr_tce_blocking_domain_ops with these two functions and assign it
to domain->ops when creating. Then it is really clear these functions
are only called for the DOMAIN_BLOCKED type and you don't need to
check it.
> +static void spapr_tce_iommu_detach_dev(struct iommu_domain *dom,
> + struct device *dev)
> +{
> + struct iommu_group *grp = iommu_group_get(dev);
> + struct iommu_table_group *table_group;
> +
> + table_group = iommu_group_get_iommudata(grp);
> + WARN_ON(dom->type != IOMMU_DOMAIN_BLOCKED);
> + table_group->ops->release_ownership(table_group);
> +}
Ditto
> +struct iommu_group *pSeries_pci_device_group(struct pci_controller *hose,
> + struct pci_dev *pdev)
> +{
> + struct device_node *pdn, *dn = pdev->dev.of_node;
> + struct iommu_group *grp;
> + struct pci_dn *pci;
> +
> + pdn = pci_dma_find(dn, NULL);
> + if (!pdn || !PCI_DN(pdn))
> + return ERR_PTR(-ENODEV);
> +
> + pci = PCI_DN(pdn);
> + if (!pci->table_group)
> + return ERR_PTR(-ENODEV);
> +
> + grp = pci->table_group->group;
> + if (!grp)
> + return ERR_PTR(-ENODEV);
> +
> + return iommu_group_ref_get(grp);
Not for this series, but this is kind of backwards, the driver
specific data (ie the table_group) should be in
iommu_group_get_iommudata()...
> diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
> index 8a65ea61744c..3b53b466e49b 100644
> --- a/drivers/vfio/vfio_iommu_spapr_tce.c
> +++ b/drivers/vfio/vfio_iommu_spapr_tce.c
> @@ -1152,8 +1152,6 @@ static void tce_iommu_release_ownership(struct tce_container *container,
> for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i)
> if (container->tables[i])
> table_group->ops->unset_window(table_group, i);
> -
> - table_group->ops->release_ownership(table_group);
> }
>
> static long tce_iommu_take_ownership(struct tce_container *container,
> @@ -1161,10 +1159,6 @@ static long tce_iommu_take_ownership(struct tce_container *container,
> {
> long i, ret = 0;
>
> - ret = table_group->ops->take_ownership(table_group);
> - if (ret)
> - return ret;
> -
> /* Set all windows to the new group */
> for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
> struct iommu_table *tbl = container->tables[i];
> @@ -1183,8 +1177,6 @@ static long tce_iommu_take_ownership(struct tce_container *container,
> for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i)
> table_group->ops->unset_window(table_group, i);
>
> - table_group->ops->release_ownership(table_group);
> -
This is great, makes alot of sense.
Anyhow, it all looks fine to me as is even:
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Jason
