linux-kernel - [PATCH v4 1/2] perf/smmuv3: Don't reserve the PMCG register spaces

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Date:   Sat, 30 Jan 2021 15:14:13 +0800
From:   Zhen Lei <thunder.leizhen@...wei.com>
To:     Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
        "Mark Rutland" <mark.rutland@....com>,
        Joerg Roedel <joro@...tes.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        iommu <iommu@...ts.linux-foundation.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
CC:     Zhen Lei <thunder.leizhen@...wei.com>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>
Subject: [PATCH v4 1/2] perf/smmuv3: Don't reserve the PMCG register spaces

According to the SMMUv3 specification:
Each PMCG counter group is represented by one 4KB page (Page 0) with one
optional additional 4KB page (Page 1), both of which are at IMPLEMENTATION
DEFINED base addresses.

This means that the PMCG register spaces may be within the 64KB pages of
the SMMUv3 register space. When both the SMMU and PMCG drivers reserve
their own resources, a resource conflict occurs.

To avoid this conflict, don't reserve the PMCG regions.

Suggested-by: Robin Murphy <robin.murphy@....com>
Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
---
 drivers/perf/arm_smmuv3_pmu.c | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c
index 74474bb322c3f26..5e894f957c7b935 100644
--- a/drivers/perf/arm_smmuv3_pmu.c
+++ b/drivers/perf/arm_smmuv3_pmu.c
@@ -793,17 +793,30 @@ static int smmu_pmu_probe(struct platform_device *pdev)
 		.capabilities	= PERF_PMU_CAP_NO_EXCLUDE,
 	};
 
-	smmu_pmu->reg_base = devm_platform_get_and_ioremap_resource(pdev, 0, &res_0);
-	if (IS_ERR(smmu_pmu->reg_base))
-		return PTR_ERR(smmu_pmu->reg_base);
+	/*
+	 * The register spaces of the PMCG may be in the register space of
+	 * other devices. For example, SMMU. Therefore, the PMCG resources are
+	 * not reserved to avoid resource conflicts with other drivers.
+	 */
+	res_0 = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res_0)
+		return ERR_PTR(-EINVAL);
+	smmu_pmu->reg_base = devm_ioremap(dev, res_0->start, resource_size(res_0));
+	if (!smmu_pmu->reg_base)
+		return ERR_PTR(-ENOMEM);
 
 	cfgr = readl_relaxed(smmu_pmu->reg_base + SMMU_PMCG_CFGR);
 
 	/* Determine if page 1 is present */
 	if (cfgr & SMMU_PMCG_CFGR_RELOC_CTRS) {
-		smmu_pmu->reloc_base = devm_platform_ioremap_resource(pdev, 1);
-		if (IS_ERR(smmu_pmu->reloc_base))
-			return PTR_ERR(smmu_pmu->reloc_base);
+		struct resource *res_1;
+
+		res_1 = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+		if (!res_1)
+			return ERR_PTR(-EINVAL);
+		smmu_pmu->reloc_base = devm_ioremap(dev, res_1->start, resource_size(res_1));
+		if (!smmu_pmu->reloc_base)
+			return ERR_PTR(-ENOMEM);
 	} else {
 		smmu_pmu->reloc_base = smmu_pmu->reg_base;
 	}
-- 
1.8.3