On 2022/8/30 01:27, Jason Gunthorpe wrote:
On Mon, Aug 29, 2022 at 11:40:24AM +0800, Baolu Lu wrote:
On 2022/8/26 22:52, Jason Gunthorpe wrote:
On Fri, Aug 26, 2022 at 08:11:31PM +0800, Lu Baolu wrote:
Allocate the blocking domain when probing devices if the driver supports
blocking domain allocation. Otherwise, revert to the previous behavior,
that is, use UNMANAGED domain instead when the blocking domain is needed.
Signed-off-by: Lu Baolu<baolu.lu@xxxxxxxxxxxxxxx>
Tested-by: Zhangfei Gao<zhangfei.gao@xxxxxxxxxx>
Tested-by: Tony Zhu<tony.zhu@xxxxxxxxx>
---
drivers/iommu/iommu.c | 29 +++++++++++++++++------------
1 file changed, 17 insertions(+), 12 deletions(-)
This seems like a lot of overhead to allocate these things for every
group?
Why not add a simple refcount on the blocking domain instead and
allocate the domain on the pasid attach like we do for ownership?
I am working towards implementing static instance of blocking domain for
each IOMMU driver, and then, there's no much overhead to allocate it in
the probing device path.
Well, I thought about that and I don't think we can get
there in a short order.
Yes. Fair enough.
Would rather you progress this series without
getting entangled in such a big adventure
Agreed. I will drop this patch and add below code in the iommu
interface:
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -3219,6 +3219,26 @@ int iommu_attach_device_pasid(struct iommu_domain
*domain,
return -ENODEV;
mutex_lock(&group->mutex);
+
+ /*
+ * The underlying IOMMU driver needs to support blocking domain
+ * allocation and the callback to block DMA transactions with a
+ * specific PASID.
+ */
+ if (!group->blocking_domain) {
+ group->blocking_domain = __iommu_domain_alloc(dev->bus,
+ IOMMU_DOMAIN_BLOCKED);
+ if (!group->blocking_domain) {
+ ret = -ENODEV;
+ goto out_unlock;
+ }
+ }
+
+ if (!group->blocking_domain->ops->set_dev_pasid) {
+ ret = -EOPNOTSUPP;
+ goto out_unlock;
+ }
+
curr = xa_cmpxchg(&group->pasid_array, pasid, NULL, domain,
GFP_KERNEL);
if (curr) {
ret = xa_err(curr) ? : -EBUSY;
Currently both ARM SMMUv3 and VT-d drivers use static blocking domain.
Hence I didn't use a refcount for blocking domain release here.
Best regards,
baolu
