Re: [PATCH v3 2/2] s390x/pci: Change reset method from legacy to resettable exit

[Eric Farman <farman@linux.ibm.com>]

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: qemu-stable@nongnu.org
>> Reviewed-by: Philippe Mathieu-Daudé <philmd@oss.qualcomm.com>
>> Tested-by: Omar Elghoul <oelghoul@linux.ibm.com>
>> Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
> 
> Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>

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