HW with CANWBS is always cache coherent and ignores PCI No Snoop requests
as well. This meets the requirement for IOMMU_CAP_ENFORCE_CACHE_COHERENCY,
so let's return it.
Implement the enforce_cache_coherency() op to reject attaching devices
that don't have CANWBS.
Reviewed-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
Reviewed-by: Mostafa Saleh <smostafa@xxxxxxxxxx>
Tested-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
---
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 31 +++++++++++++++++++++
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 7 +++++
2 files changed, 38 insertions(+)
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 acf250aeb18b27..38725810c14eeb 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2293,6 +2293,8 @@ static bool arm_smmu_capable(struct device *dev, enum iommu_cap cap)
case IOMMU_CAP_CACHE_COHERENCY:
/* Assume that a coherent TCU implies coherent TBUs */
return master->smmu->features & ARM_SMMU_FEAT_COHERENCY;
+ case IOMMU_CAP_ENFORCE_CACHE_COHERENCY:
+ return arm_smmu_master_canwbs(master);
case IOMMU_CAP_NOEXEC:
case IOMMU_CAP_DEFERRED_FLUSH:
return true;
@@ -2303,6 +2305,26 @@ static bool arm_smmu_capable(struct device *dev, enum iommu_cap cap)
}
}
+static bool arm_smmu_enforce_cache_coherency(struct iommu_domain *domain)
+{
+ struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
+ struct arm_smmu_master_domain *master_domain;
+ unsigned long flags;
+ bool ret = true;
+
+ spin_lock_irqsave(&smmu_domain->devices_lock, flags);
+ list_for_each_entry(master_domain, &smmu_domain->devices,
+ devices_elm) {
+ if (!arm_smmu_master_canwbs(master_domain->master)) {
+ ret = false;
+ break;
+ }
+ }
+ smmu_domain->enforce_cache_coherency = ret;
+ spin_unlock_irqrestore(&smmu_domain->devices_lock, flags);
+ return ret;
+}
+
struct arm_smmu_domain *arm_smmu_domain_alloc(void)
{
struct arm_smmu_domain *smmu_domain;
@@ -2731,6 +2753,14 @@ static int arm_smmu_attach_prepare(struct arm_smmu_attach_state *state,
* one of them.
*/
spin_lock_irqsave(&smmu_domain->devices_lock, flags);
+ if (smmu_domain->enforce_cache_coherency &&
+ !arm_smmu_master_canwbs(master)) {
+ spin_unlock_irqrestore(&smmu_domain->devices_lock,
+ flags);
+ kfree(master_domain);
+ return -EINVAL;
+ }
+
if (state->ats_enabled)
atomic_inc(&smmu_domain->nr_ats_masters);
list_add(&master_domain->devices_elm, &smmu_domain->devices);
@@ -3493,6 +3523,7 @@ static struct iommu_ops arm_smmu_ops = {
.owner = THIS_MODULE,
.default_domain_ops = &(const struct iommu_domain_ops) {
.attach_dev = arm_smmu_attach_dev,
+ .enforce_cache_coherency = arm_smmu_enforce_cache_coherency,
.set_dev_pasid = arm_smmu_s1_set_dev_pasid,
.map_pages = arm_smmu_map_pages,
.unmap_pages = arm_smmu_unmap_pages,
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
index 1e9952ca989f87..06e3d88932df12 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -811,6 +811,7 @@ struct arm_smmu_domain {
/* List of struct arm_smmu_master_domain */
struct list_head devices;
spinlock_t devices_lock;
+ bool enforce_cache_coherency : 1;
struct mmu_notifier mmu_notifier;
};
@@ -893,6 +894,12 @@ int arm_smmu_init_one_queue(struct arm_smmu_device *smmu,
int arm_smmu_cmdq_init(struct arm_smmu_device *smmu,
struct arm_smmu_cmdq *cmdq);
+static inline bool arm_smmu_master_canwbs(struct arm_smmu_master *master)
+{
+ return dev_iommu_fwspec_get(master->dev)->flags &
+ IOMMU_FWSPEC_PCI_RC_CANWBS;
+}
+
#ifdef CONFIG_ARM_SMMU_V3_SVA
bool arm_smmu_sva_supported(struct arm_smmu_device *smmu);
bool arm_smmu_master_sva_supported(struct arm_smmu_master *master);
--
2.46.2
