s390x/pci: Fix endianness for zPCI BAR values.

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 <jhkim@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Farhan Ali <alifm@linux.ibm.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Message-ID: <20260206164645.1845366-1-jhkim@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

diff --git a/hw/s390x/s390-pci-inst.c b/hw/s390x/s390-pci-inst.c
index 6b67c3c109f6376a08d6b8a8d8aefe2dac38862a..10066ca6180a7af5ec966135665573bcf6319272 100644 (file)
--- 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,