[ Upstream commit 3f54c447df34ff9efac7809a4a80fd3208efc619 ]
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 --- 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 d3880010c6cf..d8b73da6447d 100644 --- a/drivers/iommu/arm-smmu-v3.c +++ b/drivers/iommu/arm-smmu-v3.c @@ -2454,13 +2454,9 @@ 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); @@ -2553,6 +2549,8 @@ 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) {