On 10/28/26 6:46 PM, Farhan Ali wrote:
> On subsystem reset of the s390 PCI host bridge (TYPE_S390_PCI_HOST_BRIDGE),
> child buses S390PCIBus and PCIBus are reset in order. Because S390PCIBus
> devices are reset first via the legacy reset hook, IOMMU mappings are torn
> down before the PCI device itself is reset. For a PCI passthrough device
> this opens a window where the device may issue DMA to addresses that no
> longer have valid IOMMU mappings, causing an error (PEC 0x7) on the host.
>
> The QEMU reset documentation (docs/devel/reset.rst) specifies that IOMMUs
> should perform teardown in the resettable 'exit' phase, after all devices
> have completed their 'hold' phase. Move the S390PCIBusDevice reset logic
> from the legacy reset hook to the resettable exit phase to close this
> window.
>
> Fixes: 3e5cfba3ca0a ("s390x/pci: introduce S390PCIBusDevice qdev")
> Cc: [email protected]
> Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
> Tested-by: Omar Elghoul <[email protected]>
> Signed-off-by: Farhan Ali <[email protected]>
Reviewed-by: Matthew Rosato <[email protected]>
