The test isn't going to work if a group doesn't exist. Normally this isn't
a problem since VFIO isn't going to create a device if there is no group,
but the special CONFIG_VFIO_NOIOMMU behavior allows bypassing this
prevention. The new cap test effectively forces a group and breaks this
config option.
Move the cap test to vfio_group_find_or_alloc() which is the earliest time
we know we have a group available and thus are not running in noiommu mode.
Fixes: e8ae0e140c05 ("vfio: Require that devices support DMA cache coherence")
Reported-by "chenxiang (M)" <chenxiang66@xxxxxxxxxxxxx>
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
---
drivers/vfio/vfio.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)
This should fixe the issue with dpdk on noiommu, but I've left PPC out.
I think the right way to fix PPC is to provide the iommu_ops for the devices
groups it is creating. They don't have to be fully functional - eg they don't
have to to create domains, but if the ops exist they can correctly respond to
iommu_capable() and we don't need special code here to work around PPC being
weird.
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index e43b9496464bbf..cbb693359502d9 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -552,6 +552,16 @@ static struct vfio_group *vfio_group_find_or_alloc(struct device *dev)
if (!iommu_group)
return ERR_PTR(-EINVAL);
+ /*
+ * VFIO always sets IOMMU_CACHE because we offer no way for userspace to
+ * restore cache coherency. It has to be checked here because it is only
+ * valid for cases where we are using iommu groups.
+ */
+ if (!iommu_capable(dev->bus, IOMMU_CAP_CACHE_COHERENCY)) {
+ iommu_group_put(iommu_group);
+ return ERR_PTR(-EINVAL);
+ }
+
group = vfio_group_get_from_iommu(iommu_group);
if (!group)
group = vfio_create_group(iommu_group, VFIO_IOMMU);
@@ -604,13 +614,6 @@ static int __vfio_register_dev(struct vfio_device *device,
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))
- return -EINVAL;
-
return __vfio_register_dev(device,
vfio_group_find_or_alloc(device->dev));
}
base-commit: e2475f7b57209e3c67bf856e1ce07d60d410fb40
--
2.37.0
