During zPCI scan, BAR configuration data retrieved via CLP Query was misinterpreted due to an endianness mismatch between QEMU and the guest kernel.
The guest kernel's clp_store_query_pci_fn() expects BAR values in little-endian format and converts them with le32_to_cpu(). However, QEMU was incorrectly sending them in big-endian format, not following the architecture specification. This caused incorrect bit-swapping in the kernel, leading zpci_setup_bus_resources() to perform registration checks against invalid flags, making the process ineffective. Observation values for zPCI device (NVMe passthrough): LPAR from real CLP: [ 0.865595] Resource: PCI Bus 0000:00 -> zdev->bar[0].val: 0x4 [ 0.865597] start: 0x4000000000000000 [ 0.865598] end: 0x4000000000003fff [ 0.865600] flags: 0x100200 QEMU before fix (wrong): [ 0.601083] Resource: PCI Bus 0001:00 -> zdev->bar[0].val: 0x4000000 [ 0.601085] start: 0x4003000000000000 [ 0.601086] end: 0x4003000000003fff [ 0.601087] flags: 0x200 QEMU after fix (correct): [ 0.601116] Resource: PCI Bus 0001:00 -> zdev->bar[0].val: 0x4 [ 0.601117] start: 0x4003000000000000 [ 0.601118] end: 0x4003000000003fff [ 0.601119] flags: 0x100200 Signed-off-by: Jaehoon Kim <[email protected]> --- hw/s390x/s390-pci-inst.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hw/s390x/s390-pci-inst.c b/hw/s390x/s390-pci-inst.c index 6b67c3c109..10066ca618 100644 --- a/hw/s390x/s390-pci-inst.c +++ b/hw/s390x/s390-pci-inst.c @@ -307,7 +307,7 @@ int clp_service_call(S390CPU *cpu, uint8_t r2, uintptr_t ra) uint32_t data = pci_get_long(pbdev->pdev->config + PCI_BASE_ADDRESS_0 + (i * 4)); - stl_be_p(&resquery->bar[i], data); + stl_le_p(&resquery->bar[i], data); resquery->bar_size[i] = pbdev->pdev->io_regions[i].size ? ctz64(pbdev->pdev->io_regions[i].size) : 0; trace_s390_pci_bar(i, -- 2.50.1
