[PATCH v2 05/10] iommu/arm-smmu-v3: Flush iotlb in arm_smmu_iotlb_tag_free()

Nicolin Chen
2026-01-22T01:25:02Z

If the IOTLB cache tag is no longer used by any device, flush the entries
tagged with the ASID/VMID, before the tag gets free-ed.

Drop the free_fn callback accordingly since it's the same thing.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 3 +-
.../iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c | 6 +--
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 46 +++++--------------
3 files changed, 16 insertions(+), 39 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 812314aaaa6a..696ebb89ffa3 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -1024,8 +1024,7 @@ void arm_smmu_make_sva_cd(struct arm_smmu_cd *target,
struct arm_smmu_invs *arm_smmu_invs_merge(struct arm_smmu_invs *invs,
struct arm_smmu_invs *to_merge);
void arm_smmu_invs_unref(struct arm_smmu_invs *invs,
- struct arm_smmu_invs *to_unref,
- void (*free_fn)(struct arm_smmu_inv *inv));
+ struct arm_smmu_invs *to_unref);
struct arm_smmu_invs *arm_smmu_invs_purge(struct arm_smmu_invs *invs);
#endif

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c
index 81551fad727b..d66931b56b46 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c
@@ -635,7 +635,7 @@ static void arm_smmu_v3_invs_test(struct kunit *test)
results2[0], results2[1]);

/* Test3: unref invs2 (same array) */
- arm_smmu_invs_unref(test_a, &invs2, NULL);
+ arm_smmu_invs_unref(test_a, &invs2);
arm_smmu_v3_invs_test_verify(test, test_a, ARRAY_SIZE(results3[0]),
results3[0], results3[1]);
KUNIT_EXPECT_EQ(test, test_a->num_trashes, 0);
@@ -647,7 +647,7 @@ static void arm_smmu_v3_invs_test(struct kunit *test)
results4[0], results4[1]);

/* Test5: unref invs1 (same array) */
- arm_smmu_invs_unref(test_b, &invs1, NULL);
+ arm_smmu_invs_unref(test_b, &invs1);
arm_smmu_v3_invs_test_verify(test, test_b, ARRAY_SIZE(results5[0]),
results5[0], results5[1]);
KUNIT_EXPECT_EQ(test, test_b->num_trashes, 2);
@@ -659,7 +659,7 @@ static void arm_smmu_v3_invs_test(struct kunit *test)
results6[0], results6[1]);

/* Test7: unref invs3 (same array) */
- arm_smmu_invs_unref(test_a, &invs3, NULL);
+ arm_smmu_invs_unref(test_a, &invs3);
KUNIT_EXPECT_EQ(test, test_a->num_invs, 0);
KUNIT_EXPECT_EQ(test, test_a->num_trashes, 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 d10593823353..5a7032081553 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -1168,8 +1168,6 @@ EXPORT_SYMBOL_IF_KUNIT(arm_smmu_invs_merge);
* the user counts without deletions
* @invs: the base invalidation array
* @to_unref: an array of invlidations to decrease their user counts
- * @free_fn: A callback function to invoke, when an entry's user count reduces
- * to 0
*
* Return: the number of trash entries in the array, for arm_smmu_invs_purge()
*
@@ -1188,8 +1186,7 @@ EXPORT_SYMBOL_IF_KUNIT(arm_smmu_invs_merge);
*/
VISIBLE_IF_KUNIT
void arm_smmu_invs_unref(struct arm_smmu_invs *invs,
- struct arm_smmu_invs *to_unref,
- void (*free_fn)(struct arm_smmu_inv *inv))
+ struct arm_smmu_invs *to_unref)
{
unsigned long flags;
size_t num_invs = 0;
@@ -1207,9 +1204,6 @@ void arm_smmu_invs_unref(struct arm_smmu_invs *invs,
continue;
}

- /* KUNIT test doesn't pass in a free_fn */
- if (free_fn)
- free_fn(&invs->inv[i]);
/* Notify the caller to free the iotlb tag */
refcount_set(&to_unref->inv[j].users, 0);
invs->num_trashes++;
@@ -3188,6 +3182,16 @@ int arm_smmu_domain_get_iotlb_tag(struct arm_smmu_domain *smmu_domain,

static void arm_smmu_iotlb_tag_free(struct arm_smmu_inv *tag)
{
+ struct arm_smmu_cmdq_ent cmd = {
+ .opcode = tag->nsize_opcode,
+ };
+
+ if (tag->type == INV_TYPE_S1_ASID)
+ cmd.tlbi.asid = tag->id;
+ else
+ cmd.tlbi.vmid = tag->id;
+ arm_smmu_cmdq_issue_cmd_with_sync(tag->smmu, &cmd);
+
if (tag->type == INV_TYPE_S1_ASID)
xa_erase(&arm_smmu_asid_xa, tag->id);
else if (tag->type == INV_TYPE_S2_VMID)
@@ -3437,31 +3441,6 @@ arm_smmu_install_new_domain_invs(struct arm_smmu_attach_state *state)
kfree_rcu(invst->old_invs, rcu);
}

-/*
- * When an array entry's users count reaches zero, it means the ASID/VMID is no
- * longer being invalidated by map/unmap and must be cleaned. The rule is that
- * all ASIDs/VMIDs not in an invalidation array are left cleared in the IOTLB.
- */
-static void arm_smmu_inv_flush_iotlb_tag(struct arm_smmu_inv *inv)
-{
- struct arm_smmu_cmdq_ent cmd = {};
-
- switch (inv->type) {
- case INV_TYPE_S1_ASID:
- cmd.tlbi.asid = inv->id;
- break;
- case INV_TYPE_S2_VMID:
- /* S2_VMID using nsize_opcode covers S2_VMID_S1_CLEAR */
- cmd.tlbi.vmid = inv->id;
- break;
- default:
- return;
- }
-
- cmd.opcode = inv->nsize_opcode;
- arm_smmu_cmdq_issue_cmd_with_sync(inv->smmu, &cmd);
-}
-
/* Should be installed after arm_smmu_install_ste_for_dev() */
static void
arm_smmu_install_old_domain_invs(struct arm_smmu_attach_state *state)
@@ -3475,8 +3454,7 @@ arm_smmu_install_old_domain_invs(struct arm_smmu_attach_state *state)
if (!invst->invs_ptr)
return;

- arm_smmu_invs_unref(old_invs, invst->new_invs,
- arm_smmu_inv_flush_iotlb_tag);
+ arm_smmu_invs_unref(old_invs, invst->new_invs);
if (!refcount_read(&invst->new_invs->inv[0].users))
arm_smmu_iotlb_tag_free(&invst->tag);

--
2.43.0