On 5/7/25 17:21, Tushar Dave wrote:
On 5/7/25 06:59, Yi Liu wrote:
On 2025/5/6 05:15, Tushar Dave wrote:
Generally PASID support requires ACS settings that usually create
single device groups, but there are some niche cases where we can get
multi-device groups and still have working PASID support. The primary
issue is that PCI switches are not required to treat PASID tagged TLPs
specially so appropriate ACS settings are required to route all TLPs to
the host bridge if PASID is going to work properly.
pci_enable_pasid() does check that each device that will use PASID has
the proper ACS settings to achieve this routing.
However, no-PASID devices can be combined with PASID capable devices
within the same topology using non-uniform ACS settings. In this case
the no-PASID devices may not have strict route to host ACS flags and
end up being grouped with the PASID devices.
This configuration fails to allow use of the PASID within the iommu
core code which wrongly checks if the no-PASID device supports PASID.
Fix this by ignoring no-PASID devices during the PASID validation. They
will never issue a PASID TLP anyhow so they can be ignored.
Fixes: c404f55c26fc ("iommu: Validate the PASID in iommu_attach_device_pasid()")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Tushar Dave <tdave@xxxxxxxxxx>
---
changes in v3:
- addressed review comment from Vasant.
drivers/iommu/iommu.c | 27 +++++++++++++++++++--------
1 file changed, 19 insertions(+), 8 deletions(-)
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 60aed01e54f2..636fc68a8ec0 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -3329,10 +3329,12 @@ static int __iommu_set_group_pasid(struct iommu_domain
*domain,
int ret;
for_each_group_device(group, device) {
- ret = domain->ops->set_dev_pasid(domain, device->dev,
- pasid, NULL);
- if (ret)
- goto err_revert;
+ if (device->dev->iommu->max_pasids > 0) {
+ ret = domain->ops->set_dev_pasid(domain, device->dev,
+ pasid, NULL);
+ if (ret)
+ goto err_revert;
+ }
}
return 0;
@@ -3342,7 +3344,8 @@ static int __iommu_set_group_pasid(struct iommu_domain
*domain,
for_each_group_device(group, device) {
if (device == last_gdev)
break;
- iommu_remove_dev_pasid(device->dev, pasid, domain);
+ if (device->dev->iommu->max_pasids > 0)
+ iommu_remove_dev_pasid(device->dev, pasid, domain);
Reviewed-by: Yi Liu <yi.l.liu@xxxxxxxxx>
with a nit. would it save some loc by adding the max_pasids check in
iommu_remove_dev_pasid()?
With current code:
drivers/iommu/iommu.c | 27 +++++++++++++++++++--------
1 file changed, 19 insertions(+), 8 deletions(-)
If I move the pasid check in iommu_remove_dev_pasid(), it would be:
drivers/iommu/iommu.c | 23 ++++++++++++++++-------
1 file changed, 16 insertions(+), 7 deletions(-)
Yi Liu,
Should I send v4 with the change below or we are good with v3?
-Tushar
e.g.
@@ -3318,8 +3318,9 @@ static void iommu_remove_dev_pasid(struct device *dev,
ioasid_t pasid,
const struct iommu_ops *ops = dev_iommu_ops(dev);
struct iommu_domain *blocked_domain = ops->blocked_domain;
- WARN_ON(blocked_domain->ops->set_dev_pasid(blocked_domain,
- dev, pasid, domain));
+ if (dev->iommu->max_pasids > 0)
+ WARN_ON(blocked_domain->ops->set_dev_pasid(blocked_domain,
+ dev, pasid, domain));
}
static int __iommu_set_group_pasid(struct iommu_domain *domain,
@@ -3329,10 +3330,12 @@ static int __iommu_set_group_pasid(struct iommu_domain
*domain,
int ret;
for_each_group_device(group, device) {
- ret = domain->ops->set_dev_pasid(domain, device->dev,
- pasid, NULL);
- if (ret)
- goto err_revert;
+ if (device->dev->iommu->max_pasids > 0) {
+ ret = domain->ops->set_dev_pasid(domain, device->dev,
+ pasid, NULL);
+ if (ret)
+ goto err_revert;
+ }
}
return 0;
Last hunk remain same as before for iommu_attach_device_pasid()
Let me know.
-Tushar
}
return ret;
}
@@ -3353,8 +3356,10 @@ static void __iommu_remove_group_pasid(struct
iommu_group *group,
{
struct group_device *device;
- for_each_group_device(group, device)
- iommu_remove_dev_pasid(device->dev, pasid, domain);
+ for_each_group_device(group, device) {
+ if (device->dev->iommu->max_pasids > 0)
+ iommu_remove_dev_pasid(device->dev, pasid, domain);
+ }
}
/*
@@ -3391,7 +3396,13 @@ int iommu_attach_device_pasid(struct iommu_domain *domain,
mutex_lock(&group->mutex);
for_each_group_device(group, device) {
- if (pasid >= device->dev->iommu->max_pasids) {
+ /*
+ * Skip PASID validation for devices without PASID support
+ * (max_pasids = 0). These devices cannot issue transactions
+ * with PASID, so they don't affect group's PASID usage.
+ */
+ if ((device->dev->iommu->max_pasids > 0) &&
+ (pasid >= device->dev->iommu->max_pasids)) {
ret = -EINVAL;
goto out_unlock;
}
