For platform devices that support SubstreamID (SSID), firmware provides the number of supported SSID bits. Restrict it to what the SMMU supports and cache it into master->ssid_bits.
Signed-off-by: Jean-Philippe Brucker <[email protected]> --- drivers/iommu/arm-smmu-v3.c | 11 +++++++++++ drivers/iommu/of_iommu.c | 6 +++++- include/linux/iommu.h | 1 + 3 files changed, 17 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c index 4d5a694f02c2..3254f473e681 100644 --- a/drivers/iommu/arm-smmu-v3.c +++ b/drivers/iommu/arm-smmu-v3.c @@ -604,6 +604,7 @@ struct arm_smmu_master { struct list_head domain_head; u32 *sids; unsigned int num_sids; + unsigned int ssid_bits; bool ats_enabled :1; }; @@ -2097,6 +2098,16 @@ static int arm_smmu_add_device(struct device *dev) } } + master->ssid_bits = min(smmu->ssid_bits, fwspec->num_pasid_bits); + + /* + * If the SMMU doesn't support 2-stage CD, limit the linear + * tables to a reasonable number of contexts, let's say + * 64kB / sizeof(ctx_desc) = 1024 = 2^10 + */ + if (!(smmu->features & ARM_SMMU_FEAT_2_LVL_CDTAB)) + master->ssid_bits = min(master->ssid_bits, 10U); + group = iommu_group_get_for_dev(dev); if (!IS_ERR(group)) { iommu_group_put(group); diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c index f04a6df65eb8..04f4f6b95d82 100644 --- a/drivers/iommu/of_iommu.c +++ b/drivers/iommu/of_iommu.c @@ -206,8 +206,12 @@ const struct iommu_ops *of_iommu_configure(struct device *dev, if (err) break; } - } + fwspec = dev_iommu_fwspec_get(dev); + if (!err && fwspec) + of_property_read_u32(master_np, "pasid-num-bits", + &fwspec->num_pasid_bits); + } /* * Two success conditions can be represented by non-negative err here: diff --git a/include/linux/iommu.h b/include/linux/iommu.h index 519e40fb23ce..b91df613385f 100644 --- a/include/linux/iommu.h +++ b/include/linux/iommu.h @@ -536,6 +536,7 @@ struct iommu_fwspec { struct fwnode_handle *iommu_fwnode; void *iommu_priv; u32 flags; + u32 num_pasid_bits; unsigned int num_ids; u32 ids[1]; }; -- 2.21.0
