On 2022-07-01 07:17, Alexey Kardashevskiy wrote:
VFIO on POWER does not implement iommu_ops and therefore iommu_capable()
always returns false and __iommu_group_alloc_blocking_domain() always
fails.
iommu_group_claim_dma_owner() in setting container fails for the same
reason - it cannot allocate a domain.
This skips the check for platforms supporting VFIO without implementing
iommu_ops which to my best knowledge is POWER only.
This also allows setting container in absence of iommu_ops.
Fixes: 70693f470848 ("vfio: Set DMA ownership for VFIO devices")
Fixes: e8ae0e140c05 ("vfio: Require that devices support DMA cache coherence")
Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
---
Not quite sure what the proper small fix is and implementing iommu_ops
on POWER is not going to happen any time soon or ever :-/
FWIW I did wonder about this when writing [1]. Is it appropriate to have
any IOMMU API specifics outside the type1 code, or should these bits be
abstracted behind vfio_iommu_driver_ops methods?
Robin.
[1]
https://lore.kernel.org/linux-iommu/4ea5eb64246f1ee188d1a61c3e93b37756932eb7.1656092606.git.robin.murphy@xxxxxxx/
---
drivers/vfio/vfio.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 61e71c1154be..71408ab26cd0 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -605,7 +605,8 @@ int vfio_register_group_dev(struct vfio_device *device)
* VFIO always sets IOMMU_CACHE because we offer no way for userspace to
* restore cache coherency.
*/
- if (!iommu_capable(device->dev->bus, IOMMU_CAP_CACHE_COHERENCY))
+ if (device->dev->bus->iommu_ops &&
+ !iommu_capable(device->dev->bus, IOMMU_CAP_CACHE_COHERENCY))
return -EINVAL;
return __vfio_register_dev(device,
@@ -934,7 +935,7 @@ static void __vfio_group_unset_container(struct vfio_group *group)
driver->ops->detach_group(container->iommu_data,
group->iommu_group);
- if (group->type == VFIO_IOMMU)
+ if (group->type == VFIO_IOMMU && iommu_group_dma_owner_claimed(group->iommu_group))
iommu_group_release_dma_owner(group->iommu_group);
group->container = NULL;
@@ -1010,9 +1011,8 @@ static int vfio_group_set_container(struct vfio_group *group, int container_fd)
}
if (group->type == VFIO_IOMMU) {
- ret = iommu_group_claim_dma_owner(group->iommu_group, f.file);
- if (ret)
- goto unlock_out;
+ if (iommu_group_claim_dma_owner(group->iommu_group, f.file))
+ pr_warn("Failed to claim DMA owner");
}
driver = container->iommu_driver;
@@ -1021,7 +1021,8 @@ static int vfio_group_set_container(struct vfio_group *group, int container_fd)
group->iommu_group,
group->type);
if (ret) {
- if (group->type == VFIO_IOMMU)
+ if (group->type == VFIO_IOMMU &&
+ iommu_group_dma_owner_claimed(group->iommu_group))
iommu_group_release_dma_owner(
group->iommu_group);
goto unlock_out;
