[PATCH v7 6/9] iommu/arm-smmu-v3: Allocate the CD table entry in advance

Jason Gunthorpe
2024-04-16T19:29:15Z

Avoid arm_smmu_attach_dev() having to undo the changes to the
smmu_domain->devices list, acquire the cdptr earlier so we don't need to
handle that error.

Now there is a clear break in arm_smmu_attach_dev() where all the
prep-work has been done non-disruptively and we commit to making the HW
change, which cannot fail.

This completes transforming arm_smmu_attach_dev() so that it does not
disturb the HW if it fails.

Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Reviewed-by: Michael Shavit <mshavit@google.com>
Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Mostafa Saleh <smostafa@google.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 24 +++++++--------------
1 file changed, 8 insertions(+), 16 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index a0d1237272936f..0aacd95f34a479 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2661,6 +2661,7 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
struct arm_smmu_device *smmu;
struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
struct arm_smmu_master *master;
+ struct arm_smmu_cd *cdptr;

if (!fwspec)
return -ENOENT;
@@ -2689,6 +2690,12 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
if (ret)
return ret;

+ if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1) {
+ cdptr = arm_smmu_alloc_cd_ptr(master, IOMMU_NO_PASID);
+ if (!cdptr)
+ return -ENOMEM;
+ }
+
/*
* Prevent arm_smmu_share_asid() from trying to change the ASID
* of either the old or new domain while we are working on it.
@@ -2708,13 +2715,6 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
switch (smmu_domain->stage) {
case ARM_SMMU_DOMAIN_S1: {
struct arm_smmu_cd target_cd;
- struct arm_smmu_cd *cdptr;
-
- cdptr = arm_smmu_alloc_cd_ptr(master, IOMMU_NO_PASID);
- if (!cdptr) {
- ret = -ENOMEM;
- goto out_list_del;
- }

arm_smmu_make_s1_cd(&target_cd, master, smmu_domain);
arm_smmu_write_cd_entry(master, IOMMU_NO_PASID, cdptr,
@@ -2731,16 +2731,8 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
}

arm_smmu_enable_ats(master, smmu_domain);
- goto out_unlock;
-
-out_list_del:
- spin_lock_irqsave(&smmu_domain->devices_lock, flags);
- list_del_init(&master->domain_head);
- spin_unlock_irqrestore(&smmu_domain->devices_lock, flags);
-
-out_unlock:
mutex_unlock(&arm_smmu_asid_lock);
- return ret;
+ return 0;
}

static int arm_smmu_attach_dev_ste(struct device *dev,
--
2.43.2