[PATCH v3 01/13] iommu/arm-smmu-v3: Add arm_smmu_attach_release()
From: Nicolin Chen <hidden>
Date: 2026-09-01 00:35:02
Also in:
linux-iommu, linux-pci, lkml
Subsystem:
arm smmu drivers, iommu subsystem, the rest · Maintainers:
Will Deacon, Joerg Roedel, Linus Torvalds
The IOPF teardown is done in arm_smmu_remove_master_domain() when releasing the master_domain on detach, under the global arm_smmu_asid_lock mutex. But the teardown must drain any in-flight IOPF (for the old domain), before the master_domain is freed via iopf_queue_flush_dev() calling flush_workqueue() that can block on user-faulting page-fault handlers. Doing so while holding the arm_smmu_asid_lock would stall any unrelated attachment in the system. Split the teardown out of arm_smmu_remove_master_domain(), to a new helper arm_smmu_attach_release() that runs after arm_smmu_asid_lock is released. Since no other device would use the old master_domain that is being freed, it's safe to move out of arm_smmu_asid_lock (still under the protection of iommu_group->mutex). Note: this is a pure refactor; no functional change. Signed-off-by: Nicolin Chen <redacted> --- drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 2 ++ .../arm/arm-smmu-v3/arm-smmu-v3-iommufd.c | 1 + drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 33 +++++++++++++++---- 3 files changed, 30 insertions(+), 6 deletions(-)
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 50f8321e979ce..5b89bad71c102 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h@@ -1204,12 +1204,14 @@ struct arm_smmu_attach_state { struct arm_smmu_vmaster *vmaster; struct arm_smmu_inv_state old_domain_invst; struct arm_smmu_inv_state new_domain_invst; + struct arm_smmu_master_domain *old_master_domain; bool ats_enabled; }; int arm_smmu_attach_prepare(struct arm_smmu_attach_state *state, struct iommu_domain *new_domain); void arm_smmu_attach_commit(struct arm_smmu_attach_state *state); +void arm_smmu_attach_release(struct arm_smmu_attach_state *state); void arm_smmu_install_ste_for_dev(struct arm_smmu_master *master, const struct arm_smmu_ste *target);
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c
index 25982bdbcbd9a..fce026efa44f1 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c@@ -194,6 +194,7 @@ static int arm_smmu_attach_dev_nested(struct iommu_domain *domain, arm_smmu_install_ste_for_dev(master, &ste); arm_smmu_attach_commit(&state); mutex_unlock(&arm_smmu_asid_lock); + arm_smmu_attach_release(&state); return 0; }
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 5732f3ba0122d..99baa59b39c9d 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c@@ -3285,9 +3285,9 @@ arm_smmu_master_build_invs(struct arm_smmu_master *master, bool ats_enabled, return master->build_invs; } -static void arm_smmu_remove_master_domain(struct arm_smmu_master *master, - struct iommu_domain *domain, - ioasid_t ssid) +static struct arm_smmu_master_domain * +arm_smmu_remove_master_domain(struct arm_smmu_master *master, + struct iommu_domain *domain, ioasid_t ssid) { struct arm_smmu_domain *smmu_domain = to_smmu_domain_devices(domain); struct arm_smmu_master_domain *master_domain;
@@ -3295,7 +3295,7 @@ static void arm_smmu_remove_master_domain(struct arm_smmu_master *master, unsigned long flags; if (!smmu_domain) - return; + return NULL; if (domain->type == IOMMU_DOMAIN_NESTED) nested_ats_flush = to_smmu_nested_domain(domain)->enable_ats;
@@ -3310,8 +3310,23 @@ static void arm_smmu_remove_master_domain(struct arm_smmu_master *master, } spin_unlock_irqrestore(&smmu_domain->devices_lock, flags); + /* arm_smmu_attach_release() will free it */ + return master_domain; +} + +/* Release the old master_domain detached by arm_smmu_remove_master_domain() */ +void arm_smmu_attach_release(struct arm_smmu_attach_state *state) +{ + struct arm_smmu_master_domain *master_domain = state->old_master_domain; + struct arm_smmu_master *master = state->master; + + iommu_group_mutex_assert(master->dev); + + if (!master_domain) + return; arm_smmu_disable_iopf(master, master_domain); kfree(master_domain); + state->old_master_domain = NULL; } /*
@@ -3609,7 +3624,8 @@ void arm_smmu_attach_commit(struct arm_smmu_attach_state *state) arm_smmu_atc_inv_master(master, IOMMU_NO_PASID); } - arm_smmu_remove_master_domain(master, state->old_domain, state->ssid); + state->old_master_domain = arm_smmu_remove_master_domain( + master, state->old_domain, state->ssid); arm_smmu_install_old_domain_invs(state); master->ats_enabled = state->ats_enabled; }
@@ -3684,6 +3700,7 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev, arm_smmu_attach_commit(&state); mutex_unlock(&arm_smmu_asid_lock); + arm_smmu_attach_release(&state); return 0; }
@@ -3784,6 +3801,7 @@ int arm_smmu_set_pasid(struct arm_smmu_master *master, out_unlock: mutex_unlock(&arm_smmu_asid_lock); + arm_smmu_attach_release(&state); return ret; }
@@ -3804,9 +3822,11 @@ static int arm_smmu_blocking_set_dev_pasid(struct iommu_domain *new_domain, arm_smmu_clear_cd(master, pasid); if (master->ats_enabled) arm_smmu_atc_inv_master(master, pasid); - arm_smmu_remove_master_domain(master, &smmu_domain->domain, pasid); + state.old_master_domain = arm_smmu_remove_master_domain( + master, &smmu_domain->domain, pasid); arm_smmu_install_old_domain_invs(&state); mutex_unlock(&arm_smmu_asid_lock); + arm_smmu_attach_release(&state); /* * When the last user of the CD table goes away downgrade the STE back
@@ -3869,6 +3889,7 @@ static void arm_smmu_attach_dev_ste(struct iommu_domain *domain, arm_smmu_install_ste_for_dev(master, ste); arm_smmu_attach_commit(&state); mutex_unlock(&arm_smmu_asid_lock); + arm_smmu_attach_release(&state); /* * This has to be done after removing the master from the
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2.43.0