Re: [Qemu-devel] [PATCH] pci: add standard bridge device

[Avi Kivity <avi@redhat.com>]

On 08/17/2011 08:22 PM, Wen Congyang wrote:
> At 08/17/2011 04:37 PM, Wen Congyang Write:
> >  At 07/04/2011 05:43 PM, Michael S. Tsirkin Write:
> >>  This adds support for a standard pci to pci bridge,
> >>  enabling support for more than 32 PCI devices in the system.
> >>  To use, specify the device id as a 'bus' option.
> >>  Example:
> >>  	-device pci-bridge,id=bridge1 \
> >>  	-netdev user,id=u \
> >>  	-device ne2k_pci,id=net2,bus=bridge1,netdev=u
> >>
> >>  TODO: device hotplug support.
> >
> >  I try this patch, and found that when I use pci bridge, qemu will core dump.
> >
> >  Here is my command line:
> >  /usr/local2/bin/qemu-system-x86_64 -M pc-0.14 -enable-kvm -m 512 -name vm1 -drive file=/var/lib/libvirt/images/vm1.img,if=none,id=drive-ide0-0-0,format=qcow2,cache=writethrough -device ide-drive,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0,bootindex=1 -vnc 0.0.0.0:1 -device pci-bridge,id=bridge1,bus=pci.0,addr=0x08.0x0 -netdev user,id=u -device ne2k_pci,id=net2,bus=bridge1,netdev=u
> >
> >  Here is the backtrace:
> >  Core was generated by `/usr/local2/bin/qemu-system-x86_64 -M pc-0.14 -enable-kvm -m 512 -name vm1 -dri'.
> >  Program terminated with signal 11, Segmentation fault.
> >  #0  0x0000000000438e34 in memory_region_add_subregion_common (mr=0x0, offset=49152, subregion=0x1de5d58) at /home/wency/source/qemu/memory.c:1152
> >  1152	    QTAILQ_FOREACH(other,&mr->subregions, subregions_link) {
> >  Missing separate debuginfos, use: debuginfo-install SDL-1.2.14-2.el6.x86_64 celt051-0.5.1.3-0.el6.x86_64 cyrus-sasl-gssapi-2.1.23-8.el6.x86_64 cyrus-sasl-lib-2.1.23-8.el6.x86_64 cyrus-sasl-md5-2.1.23-8.el6.x86_64 cyrus-sasl-plain-2.1.23-8.el6.x86_64 db4-4.7.25-16.el6.x86_64 glib2-2.22.5-6.el6.x86_64 glibc-2.12-1.25.el6.x86_64 keyutils-libs-1.4-1.el6.x86_64 krb5-libs-1.9-9.el6.x86_64 libX11-1.3-2.el6.x86_64 libXau-1.0.5-1.el6.x86_64 libaio-0.3.107-10.el6.x86_64 libattr-2.4.44-4.el6.x86_64 libcom_err-1.41.12-7.el6.x86_64 libcurl-7.19.7-26.el6.x86_64 libgcrypt-1.4.5-5.el6.x86_64 libgpg-error-1.7-3.el6.x86_64 libidn-1.18-2.el6.x86_64 libjpeg-6b-46.el6.x86_64 libpng-1.2.44-1.el6.x86_64 libselinux-2.0.94-5.el6.x86_64 libssh2-1.2.2-7.el6.x86_64 libtasn1-2.3-3.el6.x86_64 libuuid-2.17.2-12.el6.x86_64 libxcb-1.5-1.el6.x86_64 ncurses-libs-5.7-3.20090208.el6.x86_64 nspr-4.8.7-1.el6.x86_64 nss-3.12.9-9.el6.x86_64 nss-softokn-freebl-3.12.9-3.el6.x86_64 nss-util-3.12.9-1.el6.x86_64 openld
>
> ap
> >  -2.4.23-15.el6.x86_64 openssl-1.0.0-10.el6.x86_64 pixman-0.18.4-1.el6_0.1.x86_64 spice-server-0.8.0-1.el6.x86_64 zlib-1.2.3-25.el6.x86_64
> >  (gdb) bt
> >  #0  0x0000000000438e34 in memory_region_add_subregion_common (mr=0x0, offset=49152, subregion=0x1de5d58) at /home/wency/source/qemu/memory.c:1152
> >  #1  0x0000000000439090 in memory_region_add_subregion_overlap (mr=0x0, offset=49152, subregion=0x1de5d58, priority=1) at /home/wency/source/qemu/memory.c:1194
> >  #2  0x00000000005c55fe in pci_update_mappings (d=0x1de5900) at /home/wency/source/qemu/hw/pci.c:1063
> >  #3  0x00000000005c5982 in pci_default_write_config (d=0x1de5900, addr=4, val=0, l=2) at /home/wency/source/qemu/hw/pci.c:1121
> >  #4  0x00000000005cbfbf in pci_host_config_write_common (pci_dev=0x1de5900, addr=4, limit=256, val=1, len=2) at /home/wency/source/qemu/hw/pci_host.c:54
> >  #5  0x00000000005cc0d1 in pci_data_write (s=0x1da2b90, addr=2147549188, val=1, len=2) at /home/wency/source/qemu/hw/pci_host.c:75
> >  #6  0x00000000005cc2b1 in pci_host_data_write (handler=0x1da2b60, addr=3324, val=1, len=2) at /home/wency/source/qemu/hw/pci_host.c:125
> >  #7  0x000000000042c884 in ioport_simple_writew (opaque=0x1da2b60, addr=3324, value=1) at /home/wency/source/qemu/rwhandler.c:50
> >  #8  0x0000000000499e85 in ioport_write (index=1, address=3324, data=1) at ioport.c:81
> >  #9  0x000000000049a8e1 in cpu_outw (addr=3324, val=1) at ioport.c:280
> >  #10 0x0000000000433c5d in kvm_handle_io (port=3324, data=0x7f0b30f86000, direction=1, size=2, count=1) at /home/wency/source/qemu/kvm-all.c:837
> >  #11 0x00000000004341c8 in kvm_cpu_exec (env=0x1b7fc70) at /home/wency/source/qemu/kvm-all.c:976
> >  #12 0x000000000040da99 in cpu_exec_all () at /home/wency/source/qemu/cpus.c:1102
> >  #13 0x00000000005b60c4 in main_loop () at /home/wency/source/qemu/vl.c:1392
> >  #14 0x00000000005baa49 in main (argc=20, argv=0x7ffffa6b5a38, envp=0x7ffffa6b5ae0) at /home/wency/source/qemu/vl.c:3356
> >
> >  If I do not attach any device on bus bridge1, qemu can work nice.
> >
> >  Thanks
> >  Wen Congyang
> >
>
> The following patch can fix this problem, but I'm not sure whether it is right.

It's correct but insufficient, the filtering code (pci_bridge_filter) 
needs to be updated to use the memory API.

Basically it gets simpler and correcter.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.