On Tue, 11 Apr 2023 11:26:16 +0100 Peter Maydell <peter.mayd...@linaro.org> wrote:
> On Wed, 8 Mar 2023 at 01:14, Michael S. Tsirkin <m...@redhat.com> wrote: > > > > From: Jonathan Cameron <jonathan.came...@huawei.com> > > > > The CXL r3.0 specification allows for there to be no HDM decoders on CXL > > Host Bridges if they have only a single root port. Instead, all accesses > > directed to the host bridge (as specified in CXL Fixed Memory Windows) > > are assumed to be routed to the single root port. > > Hi; in issue https://gitlab.com/qemu-project/qemu/-/issues/1586 > it's been pointed out that this commit causes an assertion > failure during 'make check' if you configure with > --enable-qom-cast-debug. You can repro by doing that and running: > > qemu-system-i386 -display none -machine q35,cxl=on -device pxb-cxl,bus=pcie.0 > > Here's a backtrace: > > Thread 1 "qemu-system-i38" received signal SIGABRT, Aborted. > __pthread_kill_implementation (no_tid=0, signo=6, > threadid=140737217810816) at ./nptl/pthread_kill.c:44 > 44 ./nptl/pthread_kill.c: No such file or directory. > (gdb) bt > #0 __pthread_kill_implementation (no_tid=0, signo=6, > threadid=140737217810816) at ./nptl/pthread_kill.c:44 > #1 __pthread_kill_internal (signo=6, threadid=140737217810816) at > ./nptl/pthread_kill.c:78 > #2 __GI___pthread_kill (threadid=140737217810816, > signo=signo@entry=6) at ./nptl/pthread_kill.c:89 > #3 0x00007ffff4b1c476 in __GI_raise (sig=sig@entry=6) at > ../sysdeps/posix/raise.c:26 > #4 0x00007ffff4b027f3 in __GI_abort () at ./stdlib/abort.c:79 > #5 0x0000555555cecfab in object_dynamic_cast_assert > (obj=obj@entry=0x555557a70b60, typename=0x555555f80406 "pxb", > file=0x555555f80357 "../../hw/pci-bridge/pci_expander_bridge.c", > line=line@entry=55, func=0x555555f8040a "PXB_DEV") at > ../../qom/object.c:890 > #6 0x00005555559c7bbd in PXB_DEV (obj=0x555557a70b60) at > ../../hw/pci-bridge/pci_expander_bridge.c:54 > #7 pxb_cxl_dev_reset (dev=0x555557a70b60) at > ../../hw/pci-bridge/pci_expander_bridge.c:314 > #8 0x00005555559bd624 in pci_qdev_realize (qdev=0x555557a70b60, > errp=0x7fffffffdd28) at ../../hw/pci/pci.c:2098 > #9 0x0000555555ce8ada in device_set_realized (obj=<optimised out>, > value=true, errp=0x7fffffffdea8) at ../../hw/core/qdev.c:510 > #10 0x0000555555cf0219 in property_set_bool > (obj=obj@entry=0x555557a70b60, v=v@entry=0x555557a727b0, > name=name@entry=0x55555601db04 "realized", opaque=0x55555687b780, > errp=errp@entry=0x7fffffffdea8) at ../../qom/object.c:2285 > #11 0x0000555555cee4e5 in object_property_set > (obj=obj@entry=0x555557a70b60, name=name@entry=0x55555601db04 > "realized", v=0x555557a727b0, errp=errp@entry=0x7fffffffdea8) at > ../../qom/object.c:1420 > #12 0x0000555555cf23cd in object_property_set_qobject > (obj=obj@entry=0x555557a70b60, name=name@entry=0x55555601db04 > "realized", value=<optimised out>, errp=errp@entry=0x7fffffffdea8) at > ../../qom/qom-qobject.c:28 > #13 0x0000555555cee93b in object_property_set_bool > (obj=0x555557a70b60, name=0x55555601db04 "realized", value=<optimised > out>, errp=0x7fffffffdea8) > at ../../qom/object.c:1489 > #14 0x0000555555a6ae42 in qdev_device_add_from_qdict > (opts=0x555557a6fb40, from_json=false, errp=0x7fffffffdea8, > errp@entry=0x555556765830 <error_fatal>) > at ../../softmmu/qdev-monitor.c:714 > #15 0x0000555555a6b202 in qdev_device_add > (opts=opts@entry=0x5555568776f0, errp=errp@entry=0x555556765830 > <error_fatal>) at ../../softmmu/qdev-monitor.c:733 > #16 0x0000555555a7367f in device_init_func (opaque=opaque@entry=0x0, > opts=0x3cd16a, opts@entry=0x5555568776f0, errp=0x6, > errp@entry=0x555556765830 <error_fatal>) > at ../../softmmu/vl.c:1140 > #17 0x0000555555e78331 in qemu_opts_foreach > (list=<optimised out>, func=0x555555a73670 <device_init_func>, > opaque=opaque@entry=0x0, errp=0x555556765830 <error_fatal>) at > ../../util/qemu-option.c:1135 > #18 0x0000555555a6dd61 in qemu_create_cli_devices () at > ../../softmmu/vl.c:2542 > #19 qmp_x_exit_preconfig (errp=<optimised out>) at ../../softmmu/vl.c:2610 > #20 0x0000555555a7177b in qemu_init (argc=<optimised out>, > argv=<optimised out>) at ../../softmmu/vl.c:3612 > #21 0x000055555587b656 in main (argc=3985770, argv=0x3cd16a) at > ../../softmmu/main.c:47 > > The problem is here: > > > -static void pxb_dev_reset(DeviceState *dev) > > +static void pxb_cxl_dev_reset(DeviceState *dev) > > This function is called from pxb_cxl_dev_realize(), > which is the realize function for TYPE_PXB_CXL_DEVICE. > That type's parent is TYPE_PCI_DEVICE. > > > { > > CXLHost *cxl = PXB_CXL_DEV(dev)->cxl.cxl_host_bridge; > > CXLComponentState *cxl_cstate = &cxl->cxl_cstate; > > + PCIHostState *hb = PCI_HOST_BRIDGE(cxl); > > uint32_t *reg_state = cxl_cstate->crb.cache_mem_registers; > > uint32_t *write_msk = cxl_cstate->crb.cache_mem_regs_write_mask; > > + int dsp_count = 0; > > > > cxl_component_register_init_common(reg_state, write_msk, > > CXL2_ROOT_PORT); > > - ARRAY_FIELD_DP32(reg_state, CXL_HDM_DECODER_CAPABILITY, TARGET_COUNT, > > 8); > > + /* > > + * The CXL specification allows for host bridges with no HDM decoders > > + * if they only have a single root port. > > + */ > > + if (!PXB_DEV(dev)->hdm_for_passthrough) { > > However, here we try to cast the device pointer to PXB_DEV. > That is not permitted because dev is not of type TYPE_PXB_DEVICE > (either directly or as a parent class). So if you have the QOM > debugging enabled then the attempt to cast causes an assertion > failure. > > > + dsp_count = pcie_count_ds_ports(hb->bus); > > + } > > + /* Initial reset will have 0 dsp so wait until > 0 */ > > + if (dsp_count == 1) { > > + cxl->passthrough = true; > > + /* Set Capability ID in header to NONE */ > > + ARRAY_FIELD_DP32(reg_state, CXL_HDM_CAPABILITY_HEADER, ID, 0); > > + } else { > > + ARRAY_FIELD_DP32(reg_state, CXL_HDM_DECODER_CAPABILITY, > > TARGET_COUNT, > > + 8); > > + } > > } > > What was the intention here with the type hierarchy? > Should TYPE_PXB_CXL_DEVICE be a subclass of TYPE_PXB_DEVICE, > or should the cxl-related functions not be trying to treat > it as a PXB device ? I can't immediately recall why, but PXB_DEV and PXB_CXL_DEV use the same struct PXBDev so here switching to PXB_CXL_DEV(dev)->hdm_for_passthrough looks to be the minimum fix. I'll dig into why / if there is a good reason for why PXB_CXL_DEV doesn't simply inherit from PXB_DEV then use runtime type checking in the few places it will matter. Jonathan > > thanks > -- PMM
