Re: [PATCH v9 05/12] iommu/arm-smmu-v3: Add ARM_SMMU_OPT_KDUMP_ADOPT for kdump kernel
Jason Gunthorpe <[email protected]>
| Newsgroups | dev.linux.lists.iommu,org.infradead.lists.linux-arm-kernel,org.kernel.vger.linux-kernel |
|---|---|
| Message-ID | <178735412600.18212.6187545852677506636.b4-review@b4> |
On Tue, 21 Jul 2026 12:48:14 -0700, Nicolin Chen <[email protected]> wrote: > When transitioning to a kdump kernel, the primary kernel might have crashed > while endpoint devices were actively bus-mastering DMA. Currently, the SMMU > driver aggressively resets the hardware during probe by clearing CR0_SMMUEN > and setting the Global Bypass Attribute (GBPA) to ABORT. > > In a kdump scenario, this aggressive reset is highly destructive: > a) If GBPA is set to ABORT, in-flight DMA will be aborted, generating fatal > PCIe AER or SErrors that may panic the kdump kernel > b) If GBPA is set to BYPASS, in-flight DMA targeting some IOVAs will bypass > the SMMU and corrupt the physical memory at those 1:1 mapped IOVAs. > > [...] Reviewed-by: Jason Gunthorpe <[email protected]> -- Jason