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From: Bjorn Andersson <bjorn.andersson@linaro.org>
To: Will Deacon <will@kernel.org>,
	Robin Murphy <robin.murphy@arm.com>,
	Joerg Roedel <joro@8bytes.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>,
	Jordan Crouse <jcrouse@codeaurora.org>,
	Rob Clark <robdclark@chromium.org>
Cc: linux-arm-msm@vger.kernel.org, iommu@lists.linux-foundation.org,
	Sibi Sankar <sibis@codeaurora.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH v3 5/8] iommu/arm-smmu-qcom: Consistently initialize stream mappings
Date: Fri,  4 Sep 2020 15:55:10 +0000	[thread overview]
Message-ID: <20200904155513.282067-6-bjorn.andersson@linaro.org> (raw)
In-Reply-To: <20200904155513.282067-1-bjorn.andersson@linaro.org>

Firmware that traps writes to S2CR to translate BYPASS into FAULT also
ignores writes of type FAULT. As such booting with "disable_bypass" set
will result in all S2CR registers left as configured by the bootloader.

This has been seen to result in indeterministic results, as these
mappings might linger and reference context banks that Linux is
reconfiguring.

Use the fact that BYPASS writes result in FAULT type to force all stream
mappings to FAULT.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
---

Changes since v2:
- None
 drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
index 284761a1cd8e..70a1eaa52e14 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
@@ -195,6 +195,7 @@ static int qcom_smmu_cfg_probe(struct arm_smmu_device *smmu)
 	unsigned int last_s2cr = ARM_SMMU_GR0_S2CR(smmu->num_mapping_groups - 1);
 	struct qcom_smmu *qsmmu = to_qcom_smmu(smmu);
 	u32 reg;
+	int i;
 
 	/*
 	 * With some firmware writes to S2CR of type FAULT are ignored, and
@@ -206,9 +207,24 @@ static int qcom_smmu_cfg_probe(struct arm_smmu_device *smmu)
 	      FIELD_PREP(ARM_SMMU_S2CR_PRIVCFG, S2CR_PRIVCFG_DEFAULT);
 	arm_smmu_gr0_write(smmu, last_s2cr, reg);
 	reg = arm_smmu_gr0_read(smmu, last_s2cr);
-	if (FIELD_GET(ARM_SMMU_S2CR_TYPE, reg) != S2CR_TYPE_BYPASS)
+	if (FIELD_GET(ARM_SMMU_S2CR_TYPE, reg) != S2CR_TYPE_BYPASS) {
 		qsmmu->bypass_broken = true;
 
+		/*
+		 * With firmware ignoring writes of type FAULT, booting the
+		 * Linux kernel with disable_bypass disabled (i.e. "enable
+		 * bypass") the initialization during probe will leave mappings
+		 * in an inconsistent state. Avoid this by configuring all
+		 * S2CRs to BYPASS.
+		 */
+		for (i = 0; i < smmu->num_mapping_groups; i++) {
+			smmu->s2crs[i].type = S2CR_TYPE_BYPASS;
+			smmu->s2crs[i].privcfg = S2CR_PRIVCFG_DEFAULT;
+			smmu->s2crs[i].cbndx = 0xff;
+			smmu->s2crs[i].count = 0;
+		}
+	}
+
 	return 0;
 }
 
-- 
2.28.0

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  parent reply	other threads:[~2020-09-04 16:03 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-04 15:55 [PATCH v3 0/8] iommu/arm-smmu: Support maintaining bootloader mappings Bjorn Andersson
2020-09-04 15:55 ` [PATCH v3 1/8] iommu/arm-smmu: Refactor context bank allocation Bjorn Andersson
2020-09-08 18:42   ` Jordan Crouse
2020-09-08 18:46     ` Jordan Crouse
2020-09-11  8:18   ` Sai Prakash Ranjan
2020-09-04 15:55 ` [PATCH v3 2/8] iommu/arm-smmu: Delay modifying domain during init Bjorn Andersson
2020-09-11  8:20   ` Sai Prakash Ranjan
2020-09-04 15:55 ` [PATCH v3 3/8] iommu/arm-smmu: Consult context bank allocator for identify domains Bjorn Andersson
2020-09-11  8:21   ` Sai Prakash Ranjan
2020-09-11  8:24   ` Sai Prakash Ranjan
2020-09-04 15:55 ` [PATCH v3 4/8] iommu/arm-smmu-qcom: Emulate bypass by using context banks Bjorn Andersson
2020-09-11  8:25   ` Sai Prakash Ranjan
2020-09-04 15:55 ` Bjorn Andersson [this message]
2020-09-11  8:26   ` [PATCH v3 5/8] iommu/arm-smmu-qcom: Consistently initialize stream mappings Sai Prakash Ranjan
2020-09-04 15:55 ` [PATCH v3 6/8] iommu/arm-smmu: Add impl hook for inherit boot mappings Bjorn Andersson
2020-09-11  8:27   ` Sai Prakash Ranjan
2020-09-11 17:13   ` Robin Murphy
2020-09-13  3:25     ` Bjorn Andersson
2020-09-21 21:08       ` Will Deacon
2020-09-24 15:55         ` Bjorn Andersson
2020-10-12  7:31         ` Bjorn Andersson
2020-10-13 16:47           ` Robin Murphy
2020-09-04 15:55 ` [PATCH v3 7/8] iommu/arm-smmu: Provide helper for allocating identity domain Bjorn Andersson
2020-09-11  8:28   ` Sai Prakash Ranjan
2020-09-04 15:55 ` [PATCH v3 8/8] iommu/arm-smmu-qcom: Setup identity domain for boot mappings Bjorn Andersson
2020-09-11  8:29   ` Sai Prakash Ranjan
2020-09-11 17:29   ` Robin Murphy
2020-09-05 22:27 ` [PATCH v3 0/8] iommu/arm-smmu: Support maintaining bootloader mappings Rob Clark
2020-09-09 14:46 ` Laurentiu Tudor
2020-09-10 22:56 ` John Stultz
2020-09-11  8:16 ` Sai Prakash Ranjan
2020-09-11 16:10 ` Amit Pundir
2020-09-16 10:09 ` Laurentiu Tudor

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