From: Will Deacon <will.deacon@arm.com>
Date: Tue, 23 Apr 2019 11:59:36 +0100
Subject: iommu/arm-smmu-v3: Don't disable SMMU in kdump kernel
Git-commit: 3f54c447df34ff9efac7809a4a80fd3208efc619
Patch-mainline: v5.2-rc1
References: bsc#1120566 bsc#1117158 bsc#1134671
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: Matthias Brugger <mbrugger@suse.com>
---
drivers/iommu/arm-smmu-v3.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 99b83fda11e4..4d5a694f02c2 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -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) {
--
2.21.0