linux-kernel - [PATCH 4.14 28/38] iommu/arm-smmu-v3: Cope with duplicated Stream IDs

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Date:   Mon,  8 Jan 2018 13:59:21 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Tomasz Nowicki <tomasz.nowicki@...iumnetworks.com>,
        Tomasz Nowicki <Tomasz.Nowicki@...ium.com>,
        "Jayachandran C." <jnair@...iumnetworks.com>,
        Robin Murphy <robin.murphy@....com>,
        Will Deacon <will.deacon@....com>
Subject: [PATCH 4.14 28/38] iommu/arm-smmu-v3: Cope with duplicated Stream IDs

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Robin Murphy <robin.murphy@....com>

commit 563b5cbe334e9503ab2b234e279d500fc4f76018 upstream.

For PCI devices behind an aliasing PCIe-to-PCI/X bridge, the bridge
alias to DevFn 0.0 on the subordinate bus may match the original RID of
the device, resulting in the same SID being present in the device's
fwspec twice. This causes trouble later in arm_smmu_write_strtab_ent()
when we wind up visiting the STE a second time and find it already live.

Avoid the issue by giving arm_smmu_install_ste_for_dev() the cleverness
to skip over duplicates. It seems mildly counterintuitive compared to
preventing the duplicates from existing in the first place, but since
the DT and ACPI probe paths build their fwspecs differently, this is
actually the cleanest and most self-contained way to deal with it.

Fixes: 8f78515425da ("iommu/arm-smmu: Implement of_xlate() for SMMUv3")
Reported-by: Tomasz Nowicki <tomasz.nowicki@...iumnetworks.com>
Tested-by: Tomasz Nowicki <Tomasz.Nowicki@...ium.com>
Tested-by: Jayachandran C. <jnair@...iumnetworks.com>
Signed-off-by: Robin Murphy <robin.murphy@....com>
Signed-off-by: Will Deacon <will.deacon@....com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/iommu/arm-smmu-v3.c |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -1646,7 +1646,7 @@ static __le64 *arm_smmu_get_step_for_sid

 static void arm_smmu_install_ste_for_dev(struct iommu_fwspec *fwspec)
 {
-	int i;
+	int i, j;
 	struct arm_smmu_master_data *master = fwspec->iommu_priv;
 	struct arm_smmu_device *smmu = master->smmu;

@@ -1654,6 +1654,13 @@ static void arm_smmu_install_ste_for_dev
 		u32 sid = fwspec->ids[i];
 		__le64 *step = arm_smmu_get_step_for_sid(smmu, sid);

+		/* Bridged PCI devices may end up with duplicated IDs */
+		for (j = 0; j < i; j++)
+			if (fwspec->ids[j] == sid)
+				break;
+		if (j < i)
+			continue;
+
 		arm_smmu_write_strtab_ent(smmu, sid, step, &master->ste);
 	}
 }