[PATCH v9 02/12] iommu/arm-smmu-v3: Skip EVTQ/PRIQ setup in kdump kernel
From: Nicolin Chen <hidden>
Date: 2026-07-21 19:49:27
Also in:
linux-iommu, lkml
Subsystem:
arm smmu drivers, iommu subsystem, the rest · Maintainers:
Will Deacon, Joerg Roedel, Linus Torvalds
In kdump cases, the crashed kernel's CDs and page tables can be corrupted, which could trigger event spamming. Also, we cannot serve page requests. Skip the EVTQ/PRIQ setup entirely rather than enabling then disabling them. Keep the queue allocations themselves, as their Q_MAX_SZ_SHIFT-capped sizes are negligible against a crashkernel reservation. Also add some inline comments explaining that. Suggested-by: Kevin Tian <kevin.tian@intel.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: Pranjal Shrivastava <praan@google.com> Signed-off-by: Nicolin Chen <redacted> --- drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 44 +++++++++++++-------- 1 file changed, 28 insertions(+), 16 deletions(-)
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 404790d2c7210..132bee5fbb1d1 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c@@ -4821,21 +4821,36 @@ static int arm_smmu_device_reset(struct arm_smmu_device *smmu) arm_smmu_cmdq_issue_cmd_with_sync( smmu, arm_smmu_make_cmd_op(CMDQ_OP_TLBI_NSNH_ALL)); - /* Event queue */ - writeq_relaxed(smmu->evtq.q.q_base, smmu->base + ARM_SMMU_EVTQ_BASE); - writel_relaxed(smmu->evtq.q.llq.prod, smmu->page1 + ARM_SMMU_EVTQ_PROD); - writel_relaxed(smmu->evtq.q.llq.cons, smmu->page1 + ARM_SMMU_EVTQ_CONS); - - enables |= CR0_EVTQEN; - ret = arm_smmu_write_reg_sync(smmu, enables, ARM_SMMU_CR0, - ARM_SMMU_CR0ACK); - if (ret) { - dev_err(smmu->dev, "failed to enable event queue\n"); - return ret; + /* + * Event queue + * + * Do not enable in a kdump case, as the crashed kernel's CDs and page + * tables may be corrupted, triggering event spamming. A disabled queue + * simply discards new events, without raising any global error. + */ + if (!is_kdump_kernel()) { + writeq_relaxed(smmu->evtq.q.q_base, + smmu->base + ARM_SMMU_EVTQ_BASE); + writel_relaxed(smmu->evtq.q.llq.prod, + smmu->page1 + ARM_SMMU_EVTQ_PROD); + writel_relaxed(smmu->evtq.q.llq.cons, + smmu->page1 + ARM_SMMU_EVTQ_CONS); + + enables |= CR0_EVTQEN; + ret = arm_smmu_write_reg_sync(smmu, enables, ARM_SMMU_CR0, + ARM_SMMU_CR0ACK); + if (ret) { + dev_err(smmu->dev, "failed to enable event queue\n"); + return ret; + } } - /* PRI queue */ - if (smmu->features & ARM_SMMU_FEAT_PRI) { + /* + * PRI queue + * + * Do not enable in a kdump case, as we cannot serve page requests. + */ + if (!is_kdump_kernel() && (smmu->features & ARM_SMMU_FEAT_PRI)) { writeq_relaxed(smmu->priq.q.q_base, smmu->base + ARM_SMMU_PRIQ_BASE); writel_relaxed(smmu->priq.q.llq.prod,
@@ -4868,9 +4883,6 @@ static int arm_smmu_device_reset(struct arm_smmu_device *smmu) return ret; } - if (is_kdump_kernel()) - enables &= ~(CR0_EVTQEN | CR0_PRIQEN); - /* Enable the SMMU interface */ enables |= CR0_SMMUEN; ret = arm_smmu_write_reg_sync(smmu, enables, ARM_SMMU_CR0,
--
2.43.0