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iommu/arm-smmu-v3: Don't disable SMMU in kdump kernel

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[ Upstream commit 3f54c447df ]

Disabling the SMMU when probing from within a kdump kernel so that all
incoming transactions are terminated can prevent the core of the crashed
kernel from being transferred off the machine if all I/O devices are
behind the SMMU.

Instead, continue to probe the SMMU after it is disabled so that we can
reinitialise it entirely and re-attach the DMA masters as they are reset.
Since the kdump kernel may not have drivers for all of the active DMA
masters, we suppress fault reporting to avoid spamming the console and
swamping the IRQ threads.

Reported-by: "Leizhen (ThunderTown)" <thunder.leizhen@huawei.com>
Tested-by: "Leizhen (ThunderTown)" <thunder.leizhen@huawei.com>
Tested-by: Bhupesh Sharma <bhsharma@redhat.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Will Deacon
2019-04-23 11:59:36 +01:00
committed by Greg Kroah-Hartman
parent f7883f9b5a
commit 4b19a45eed
1 changed files with 4 additions and 6 deletions
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10
drivers/iommu/arm-smmu-v3.c
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@@ -2414,13 +2414,9 @@ static int arm_smmu_device_reset(struct arm_smmu_device *smmu, bool bypass)
/* Clear CR0 and sync (disables SMMU and queue processing) */
reg = readl_relaxed(smmu->base + ARM_SMMU_CR0);
if (reg & CR0_SMMUEN) {
if (is_kdump_kernel()) {
arm_smmu_update_gbpa(smmu, GBPA_ABORT, 0);
arm_smmu_device_disable(smmu);
return -EBUSY;
}
dev_warn(smmu->dev, "SMMU currently enabled! Resetting...\n");
WARN_ON(is_kdump_kernel() && !disable_bypass);
arm_smmu_update_gbpa(smmu, GBPA_ABORT, 0);
}
ret = arm_smmu_device_disable(smmu);
@@ -2513,6 +2509,8 @@ static int arm_smmu_device_reset(struct arm_smmu_device *smmu, bool bypass)
return ret;
}
if (is_kdump_kernel())
enables &= ~(CR0_EVTQEN | CR0_PRIQEN);
/* Enable the SMMU interface, or ensure bypass */
if (!bypass || disable_bypass) {