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

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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>
This commit is contained in:
Will Deacon 2019-04-23 11:59:36 +01:00
parent b2fc9b4b7f
commit 3f54c447df
1 changed files with 4 additions and 6 deletions
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10
drivers/iommu/arm-smmu-v3.c
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@ -2649,13 +2649,9 @@ 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);
@ -2758,6 +2754,8 @@ 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) {