Hi! > [ 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.
> +++ b/drivers/iommu/arm-smmu-v3.c
> @@ -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);
> }
>
This changes behaviour in !is_kdump_kernel() case. Is that
ok/intended?
Best regards,
Pavel
--
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