[PATCH] iommu/arm-smmu-v3: Add missing S2FWB feature detection

["Aneesh Kumar K.V (Arm)" <aneesh.kumar@kernel.org>]

Commit 67e4fe398513 ("iommu/arm-smmu-v3: Use S2FWB for NESTED domains")
introduced S2FWB usage but omitted the corresponding feature detection.
As a result, vIOMMU allocation fails on FVP in arm_vsmmu_alloc(), due to
the following check:

	if (!arm_smmu_master_canwbs(master) &&
	    !(smmu->features & ARM_SMMU_FEAT_S2FWB))
		return ERR_PTR(-EOPNOTSUPP);

This patch adds the missing detection logic to prevent allocation
failure when S2FWB is supported.

Fixes: 67e4fe398513 ("iommu/arm-smmu-v3: Use S2FWB for NESTED domains")
Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 2 ++
 1 file changed, 2 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 358072b4e293..c7d297ceabdb 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -4405,6 +4405,8 @@ static int arm_smmu_device_hw_probe(struct arm_smmu_device *smmu)
 	reg = readl_relaxed(smmu->base + ARM_SMMU_IDR3);
 	if (FIELD_GET(IDR3_RIL, reg))
 		smmu->features |= ARM_SMMU_FEAT_RANGE_INV;
+	if (FIELD_GET(IDR3_FWB, reg))
+		smmu->features |= ARM_SMMU_FEAT_S2FWB;
 
 	/* IDR5 */
 	reg = readl_relaxed(smmu->base + ARM_SMMU_IDR5);
-- 
2.43.0