On 2/6/26 19:46, Jaehoon Kim wrote:
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
I'm picking this up for current qemu stable series.
Please let me know if I shuoldn't.
Thanks,
/mjt
