From: Robin Murphy Date: Fri, 10 Jan 2020 15:25:02 +0000 (+0000) Subject: iommu/arm-smmu: Improve SMR mask test X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=79f7a5cb87baa229b321246b3f33af875d8a1ef7;p=linux.git iommu/arm-smmu: Improve SMR mask test Make the SMR mask test more robust against SMR0 being live at probe time, which might happen once we start supporting firmware reservations for framebuffers and suchlike. Signed-off-by: Robin Murphy Signed-off-by: Will Deacon --- diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c index f067783ebd597..cca94c30b301b 100644 --- a/drivers/iommu/arm-smmu.c +++ b/drivers/iommu/arm-smmu.c @@ -971,23 +971,36 @@ static void arm_smmu_write_sme(struct arm_smmu_device *smmu, int idx) static void arm_smmu_test_smr_masks(struct arm_smmu_device *smmu) { u32 smr; + int i; if (!smmu->smrs) return; - + /* + * If we've had to accommodate firmware memory regions, we may + * have live SMRs by now; tread carefully... + * + * Somewhat perversely, not having a free SMR for this test implies we + * can get away without it anyway, as we'll only be able to 'allocate' + * these SMRs for the ID/mask values we're already trusting to be OK. + */ + for (i = 0; i < smmu->num_mapping_groups; i++) + if (!smmu->smrs[i].valid) + goto smr_ok; + return; +smr_ok: /* * SMR.ID bits may not be preserved if the corresponding MASK * bits are set, so check each one separately. We can reject * masters later if they try to claim IDs outside these masks. */ smr = FIELD_PREP(ARM_SMMU_SMR_ID, smmu->streamid_mask); - arm_smmu_gr0_write(smmu, ARM_SMMU_GR0_SMR(0), smr); - smr = arm_smmu_gr0_read(smmu, ARM_SMMU_GR0_SMR(0)); + arm_smmu_gr0_write(smmu, ARM_SMMU_GR0_SMR(i), smr); + smr = arm_smmu_gr0_read(smmu, ARM_SMMU_GR0_SMR(i)); smmu->streamid_mask = FIELD_GET(ARM_SMMU_SMR_ID, smr); smr = FIELD_PREP(ARM_SMMU_SMR_MASK, smmu->streamid_mask); - arm_smmu_gr0_write(smmu, ARM_SMMU_GR0_SMR(0), smr); - smr = arm_smmu_gr0_read(smmu, ARM_SMMU_GR0_SMR(0)); + arm_smmu_gr0_write(smmu, ARM_SMMU_GR0_SMR(i), smr); + smr = arm_smmu_gr0_read(smmu, ARM_SMMU_GR0_SMR(i)); smmu->smr_mask_mask = FIELD_GET(ARM_SMMU_SMR_MASK, smr); }