From: Robin Murphy <robin.murphy@arm.com>
Date: Fri, 10 Jan 2020 15:25:02 +0000
Subject: iommu/arm-smmu: Improve SMR mask test
Git-commit: 79f7a5cb87baa229b321246b3f33af875d8a1ef7
Patch-mainline: v5.6-rc1
References: bsc#1175713
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 <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Acked-by: Joerg Roedel <jroedel@suse.de>
---
drivers/iommu/arm-smmu.c | 23 ++++++++++++++++++-----
1 file changed, 18 insertions(+), 5 deletions(-)
diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index f067783ebd59..cca94c30b301 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);
}