When debugging and testing code on an SMMU that supports nested
translation, it can be useful to restrict the driver to a particular
stage of translation.
This patch adds a module parameter to the ARM SMMU driver to allow this
by restricting the ability of the probe() code to detect support for
only the specified stage.
Signed-off-by: Will Deacon <will.dea...@arm.com>
---
drivers/iommu/arm-smmu.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index a83cc2a2a2ca..958ae8194afe 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -326,6 +326,11 @@
#define FSYNR0_WNR (1 << 4)
+static int force_stage;
+module_param_named(force_stage, force_stage, int, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(force_stage,
+ "Force SMMU mappings to be installed at a particular stage of
translation. A value of '1' or '2' forces the corresponding stage. All other
values are ignored (i.e. no stage is forced). Note that selecting a specific
stage will disable support for nested translation.");
+
struct arm_smmu_smr {
u8 idx;
u16 mask;
@@ -1716,6 +1721,13 @@ static int arm_smmu_device_cfg_probe(struct
arm_smmu_device *smmu)
return -ENODEV;
}
#endif
+
+ /* Restrict available stages based on module parameter */
+ if (force_stage == 1)
+ id &= ~(ID0_S2TS | ID0_NTS);
+ else if (force_stage == 2)
+ id &= ~(ID0_S1TS | ID0_NTS);
+
if (id & ID0_S1TS) {
smmu->features |= ARM_SMMU_FEAT_TRANS_S1;
dev_notice(smmu->dev, "\tstage 1 translation\n");
@@ -1732,8 +1744,7 @@ static int arm_smmu_device_cfg_probe(struct
arm_smmu_device *smmu)
}
if (!(smmu->features &
- (ARM_SMMU_FEAT_TRANS_S1 | ARM_SMMU_FEAT_TRANS_S2 |
- ARM_SMMU_FEAT_TRANS_NESTED))) {
+ (ARM_SMMU_FEAT_TRANS_S1 | ARM_SMMU_FEAT_TRANS_S2))) {
dev_err(smmu->dev, "\tno translation support!\n");
return -ENODEV;
}
--
2.1.0
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
