[PATCH 6.12 437/826] iommu/tegra241-cmdqv: Fix alignment failure at max_n_shift

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6.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Nicolin Chen <nicolinc@xxxxxxxxxx>

[ Upstream commit a3799717b881aa0f4e722afb70e7b8ba84ae4f36 ]

When configuring a kernel with PAGE_SIZE=4KB, depending on its setting of
CONFIG_CMA_ALIGNMENT, VCMDQ_LOG2SIZE_MAX=19 could fail the alignment test
and trigger a WARN_ON:
    WARNING: at drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:3646
    Call trace:
     arm_smmu_init_one_queue+0x15c/0x210
     tegra241_cmdqv_init_structures+0x114/0x338
     arm_smmu_device_probe+0xb48/0x1d90

Fix it by capping max_n_shift to CMDQ_MAX_SZ_SHIFT as SMMUv3 CMDQ does.

Fixes: 918eb5c856f6 ("iommu/arm-smmu-v3: Add in-kernel support for NVIDIA Tegra241 (Grace) CMDQV")
Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20241111030226.1940737-1-nicolinc@xxxxxxxxxx
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c b/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c
index a243c543598ce..6b479592140c4 100644
--- a/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c
+++ b/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c
@@ -509,7 +509,8 @@ static int tegra241_vcmdq_alloc_smmu_cmdq(struct tegra241_vcmdq *vcmdq)
 
 	snprintf(name, 16, "vcmdq%u", vcmdq->idx);
 
-	q->llq.max_n_shift = VCMDQ_LOG2SIZE_MAX;
+	/* Queue size, capped to ensure natural alignment */
+	q->llq.max_n_shift = min_t(u32, CMDQ_MAX_SZ_SHIFT, VCMDQ_LOG2SIZE_MAX);
 
 	/* Use the common helper to init the VCMDQ, and then... */
 	ret = arm_smmu_init_one_queue(smmu, q, vcmdq->page0,
-- 
2.43.0







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