[PATCH rc v1 2/4] iommu/arm-smmu-v3: Implement is_attach_deferred() for kdump

[Nicolin Chen]

Though the kdump kernel adopts the crashed kernel's stream table, the iommu
core will still try to attach each probed device to a default domain, which
overwrites the adopted STE and breaks in-flight DMA from that device.

Implement an is_attach_deferred() callback to prevent this. For each device
that has STE.V=1 in the adopted table, defer the default domain attachment,
until the device driver explicitly requests it.

Fixes: b63b3439b856 ("iommu/arm-smmu-v3: Abort all transactions if SMMU is enabled in kdump kernel")
Cc: stable@xxxxxxxxxxxxxxx # v6.12+
Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 28 +++++++++++++++++++++
 1 file changed, 28 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 8a1de3a67f78c..ff3c1beb3739e 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -4212,6 +4212,33 @@ static void arm_smmu_remove_master(struct arm_smmu_master *master)
 	kfree(master->build_invs);
 }
 
+static bool arm_smmu_is_attach_deferred(struct device *dev)
+{
+	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
+	struct arm_smmu_device *smmu = master->smmu;
+	int i;
+
+	if (!(smmu->options & ARM_SMMU_OPT_KDUMP))
+		return false;
+
+	for (i = 0; i < master->num_streams; i++) {
+		u32 sid = master->streams[i].id;
+		struct arm_smmu_ste *step;
+
+		/* Guard against unpopulated L2 entries in the adopted table */
+		if ((smmu->features & ARM_SMMU_FEAT_2_LVL_STRTAB) &&
+		    !smmu->strtab_cfg.l2.l2ptrs[arm_smmu_strtab_l1_idx(sid)])
+			continue;
+
+		step = arm_smmu_get_step_for_sid(smmu, sid);
+		/* If the STE has the Valid bit set, defer the attach */
+		if (le64_to_cpu(step->data[0]) & STRTAB_STE_0_V)
+			return true;
+	}
+
+	return false;
+}
+
 static struct iommu_device *arm_smmu_probe_device(struct device *dev)
 {
 	int ret;
@@ -4374,6 +4401,7 @@ static const struct iommu_ops arm_smmu_ops = {
 	.hw_info		= arm_smmu_hw_info,
 	.domain_alloc_sva       = arm_smmu_sva_domain_alloc,
 	.domain_alloc_paging_flags = arm_smmu_domain_alloc_paging_flags,
+	.is_attach_deferred	= arm_smmu_is_attach_deferred,
 	.probe_device		= arm_smmu_probe_device,
 	.release_device		= arm_smmu_release_device,
 	.device_group		= arm_smmu_device_group,
-- 
2.43.0