iommu/tegra241-cmdqv: Fix alignment failure at max_n_shift

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@nvidia.com>
Link: https://lore.kernel.org/r/20241111030226.1940737-1-nicolinc@nvidia.com
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c b/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c
index 6c7770e79af6debf09ecaefea8605ff59f692a77..c8ec74f089f3d66645f58987a68a0b9feaf14bf5 100644 (file)
--- 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,