On 10/29/26 1:56 PM, Matthew Rosato wrote:
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]>

Thanks! Applied both of these to the queue for 11.2.

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