From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57740) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gWQ4T-0007Hm-B9 for qemu-devel@nongnu.org; Mon, 10 Dec 2018 13:14:22 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gWQ4P-0002h6-Am for qemu-devel@nongnu.org; Mon, 10 Dec 2018 13:14:21 -0500 Received: from mx1.redhat.com ([209.132.183.28]:58606) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gWQ4L-0002fc-GA for qemu-devel@nongnu.org; Mon, 10 Dec 2018 13:14:15 -0500 Date: Mon, 10 Dec 2018 13:14:10 -0500 From: "Michael S. Tsirkin" Message-ID: <20181210130650-mutt-send-email-mst@kernel.org> References: <7CECC2DFC21538489F72729DF5EFB4D908ABD3A4@dggemm521-mbs.china.huawei.com> <20181209211730-mutt-send-email-mst@kernel.org> <7CECC2DFC21538489F72729DF5EFB4D908AC486D@DGGEMM501-MBX.china.huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: <7CECC2DFC21538489F72729DF5EFB4D908AC486D@DGGEMM501-MBX.china.huawei.com> Subject: Re: [Qemu-devel] [BUG]Unassigned mem write during pci device hot-plug List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: xuyandong Cc: "marcel@redhat.com" , Paolo Bonzini , "qemu-devel@nongnu.org" , Zhanghailiang , "wangxin (U)" , "Huangweidong (C)" On Mon, Dec 10, 2018 at 03:12:53AM +0000, xuyandong wrote: > On Sat, Dec 08, 2018 at 11:58:59AM +0000, xuyandong wrote: > > > Hi all, > > > > > > > > > > > > In our test, we configured VM with several pci-bridges and a > > > virtio-net nic been attached with bus 4, > > > > > > After VM is startup, We ping this nic from host to judge if it is > > > working normally. Then, we hot add pci devices to this VM with bus 0. > > > > > > We found the virtio-net NIC in bus 4 is not working (can not connect) > > > occasionally, as it kick virtio backend failure with error below: > > > > > > Unassigned mem write 00000000fc803004 =3D 0x1 > > > > > > > > > > > > memory-region: pci_bridge_pci > > > > > > 0000000000000000-ffffffffffffffff (prio 0, RW): pci_bridge_pci > > > > > > 00000000fc800000-00000000fc803fff (prio 1, RW): virtio-pci > > > > > > 00000000fc800000-00000000fc800fff (prio 0, RW): > > > virtio-pci-common > > > > > > 00000000fc801000-00000000fc801fff (prio 0, RW): virtio-pci-isr > > > > > > 00000000fc802000-00000000fc802fff (prio 0, RW): > > > virtio-pci-device > > > > > > 00000000fc803000-00000000fc803fff (prio 0, RW): > > > virtio-pci-notify <- io mem unassigned > > > > > > =E2=80=A6 > > > > > > > > > > > > We caught an exceptional address changing while this problem happened, > > > show as > > > follow: > > > > > > Before pci_bridge_update_mappings=EF=BC=9A > > > > > > 00000000fc000000-00000000fc1fffff (prio 1, RW): alias > > > pci_bridge_pref_mem @pci_bridge_pci 00000000fc000000-00000000fc1fffff > > > > > > 00000000fc200000-00000000fc3fffff (prio 1, RW): alias > > > pci_bridge_pref_mem @pci_bridge_pci 00000000fc200000-00000000fc3fffff > > > > > > 00000000fc400000-00000000fc5fffff (prio 1, RW): alias > > > pci_bridge_pref_mem @pci_bridge_pci 00000000fc400000-00000000fc5fffff > > > > > > 00000000fc600000-00000000fc7fffff (prio 1, RW): alias > > > pci_bridge_pref_mem @pci_bridge_pci 00000000fc600000-00000000fc7fffff > > > > > > 00000000fc800000-00000000fc9fffff (prio 1, RW): alias > > > pci_bridge_pref_mem @pci_bridge_pci 00000000fc800000-00000000fc9fffff > > > <- correct Adress Spce > > > > > > 00000000fca00000-00000000fcbfffff (prio 1, RW): alias > > > pci_bridge_pref_mem @pci_bridge_pci 00000000fca00000-00000000fcbfffff > > > > > > 00000000fcc00000-00000000fcdfffff (prio 1, RW): alias > > > pci_bridge_pref_mem @pci_bridge_pci 00000000fcc00000-00000000fcdfffff > > > > > > 00000000fce00000-00000000fcffffff (prio 1, RW): alias > > > pci_bridge_pref_mem @pci_bridge_pci 00000000fce00000-00000000fcffffff > > > > > > > > > > > > After pci_bridge_update_mappings=EF=BC=9A > > > > > > 00000000fda00000-00000000fdbfffff (prio 1, RW): alias > > > pci_bridge_mem @pci_bridge_pci 00000000fda00000-00000000fdbfffff > > > > > > 00000000fdc00000-00000000fddfffff (prio 1, RW): alias > > > pci_bridge_mem @pci_bridge_pci 00000000fdc00000-00000000fddfffff > > > > > > 00000000fde00000-00000000fdffffff (prio 1, RW): alias > > > pci_bridge_mem @pci_bridge_pci 00000000fde00000-00000000fdffffff > > > > > > 00000000fe000000-00000000fe1fffff (prio 1, RW): alias > > > pci_bridge_mem @pci_bridge_pci 00000000fe000000-00000000fe1fffff > > > > > > 00000000fe200000-00000000fe3fffff (prio 1, RW): alias > > > pci_bridge_mem @pci_bridge_pci 00000000fe200000-00000000fe3fffff > > > > > > 00000000fe400000-00000000fe5fffff (prio 1, RW): alias > > > pci_bridge_mem @pci_bridge_pci 00000000fe400000-00000000fe5fffff > > > > > > 00000000fe600000-00000000fe7fffff (prio 1, RW): alias > > > pci_bridge_mem @pci_bridge_pci 00000000fe600000-00000000fe7fffff > > > > > > 00000000fe800000-00000000fe9fffff (prio 1, RW): alias > > > pci_bridge_mem @pci_bridge_pci 00000000fe800000-00000000fe9fffff > > > > > > fffffffffc800000-fffffffffc800000 (prio 1, RW): alias pci_bridg= e_pref_mem > > > @pci_bridge_pci fffffffffc800000-fffffffffc800000 <- Exceptional Ad= ress > > Space > >=20 > > This one is empty though right? > >=20 > > > > > > > > > We have figured out why this address becomes this value, according to > > > pci spec, pci driver can get BAR address size by writing 0xffffffff > > > to > > > > > > the pci register firstly, and then read back the value from this regi= ster. > >=20 > >=20 > > OK however as you show below the BAR being sized is the BAR if a bridge= =2E Are > > you then adding a bridge device by hotplug? >=20 > No, I just simply hot plugged a VFIO device to Bus 0, another interesting= phenomenon is > If I hot plug the device to other bus, this doesn't happened. > =20 > >=20 > >=20 > > > We didn't handle this value specially while process pci write in > > > qemu, the function call stack is: > > > > > > Pci_bridge_dev_write_config > > > > > > -> pci_bridge_write_config > > > > > > -> pci_default_write_config (we update the config[address] value here > > > -> to > > > fffffffffc800000, which should be 0xfc800000 ) > > > > > > -> pci_bridge_update_mappings > > > > > > ->pci_bridge_region_del(br, br->windows); > > > > > > -> pci_bridge_region_init > > > > > > -> > > > pci_bridge_init_alias (here pci_bridge_get_base, we use the wrong > > > value > > > fffffffffc800000) > > > > > > -> > > > memory_region_transaction_commit > > > > > > > > > > > > So, as we can see, we use the wrong base address in qemu to update the > > > memory regions, though, we update the base address to > > > > > > The correct value after pci driver in VM write the original value > > > back, the virtio NIC in bus 4 may still sends net packets concurrently > > > with > > > > > > The wrong memory region address. > > > > > > > > > > > > We have tried to skip the memory region update action in qemu while > > > detect pci write with 0xffffffff value, and it does work, but > > > > > > This seems to be not gently. > >=20 > > For sure. But I'm still puzzled as to why does Linux try to size the BA= R of the > > bridge while a device behind it is used. > >=20 > > Can you pls post your QEMU command line? >=20 > My QEMU command line: > /root/xyd/qemu-system-x86_64 -name guest=3DLinux,debug-threads=3Don -S -o= bject secret,id=3DmasterKey0,format=3Draw,file=3D/var/run/libvirt/qemu/doma= in-194-Linux/master-key.aes -machine pc-i440fx-2.8,accel=3Dkvm,usb=3Doff,du= mp-guest-core=3Doff -cpu host,+kvm_pv_eoi -bios /usr/share/OVMF/OVMF.fd -m = size=3D4194304k,slots=3D256,maxmem=3D33554432k -realtime mlock=3Doff -smp 2= 0,sockets=3D20,cores=3D1,threads=3D1 -numa node,nodeid=3D0,cpus=3D0-4,mem= =3D1024 -numa node,nodeid=3D1,cpus=3D5-9,mem=3D1024 -numa node,nodeid=3D2,c= pus=3D10-14,mem=3D1024 -numa node,nodeid=3D3,cpus=3D15-19,mem=3D1024 -uuid = 34a588c7-b0f2-4952-b39c-47fae3411439 -no-user-config -nodefaults -chardev s= ocket,id=3Dcharmonitor,path=3D/var/run/libvirt/qemu/domain-194-Linux/monito= r.sock,server,nowait -mon chardev=3Dcharmonitor,id=3Dmonitor,mode=3Dcontrol= -rtc base=3Dutc -no-hpet -global kvm-pit.lost_tick_policy=3Ddelay -no-shut= down -boot strict=3Don -device pci-bridge,chassis_nr=3D1,id=3Dpci.1,bus=3Dp= ci.0,addr=3D0x8 -device pci-bridge,chassis_nr=3D2,id=3Dpci.2,bus=3Dpci.0,ad= dr=3D0x9 -device pci-bridge,chassis_nr=3D3,id=3Dpci.3,bus=3Dpci.0,addr=3D0x= a -device pci-bridge,chassis_nr=3D4,id=3Dpci.4,bus=3Dpci.0,addr=3D0xb -devi= ce pci-bridge,chassis_nr=3D5,id=3Dpci.5,bus=3Dpci.0,addr=3D0xc -device piix= 3-usb-uhci,id=3Dusb,bus=3Dpci.0,addr=3D0x1.0x2 -device usb-ehci,id=3Dusb1,b= us=3Dpci.0,addr=3D0x10 -device nec-usb-xhci,id=3Dusb2,bus=3Dpci.0,addr=3D0x= 11 -device virtio-scsi-pci,id=3Dscsi0,bus=3Dpci.0,addr=3D0x3 -device virtio= -scsi-pci,id=3Dscsi1,bus=3Dpci.0,addr=3D0x4 -device virtio-scsi-pci,id=3Dsc= si2,bus=3Dpci.0,addr=3D0x5 -device virtio-scsi-pci,id=3Dscsi3,bus=3Dpci.0,a= ddr=3D0x6 -device virtio-serial-pci,id=3Dvirtio-serial0,bus=3Dpci.0,addr=3D= 0x7 -drive file=3D/mnt/sdb/xml/centos_74_x64_uefi.raw,format=3Draw,if=3Dnon= e,id=3Ddrive-virtio-disk0,cache=3Dnone -device virtio-blk-pci,scsi=3Doff,bu= s=3Dpci.0,addr=3D0x2,drive=3Ddrive-virtio-disk0,id=3Dvirtio-disk0,bootindex= =3D1 -drive if=3Dnone,id=3Ddrive-ide0-1-1,readonly=3Don,cache=3Dnone -devic= e ide-cd,bus=3Dide.1,unit=3D1,drive=3Ddrive-ide0-1-1,id=3Dide0-1-1 -netdev = tap,fd=3D35,id=3Dhostnet0 -device virtio-net-pci,netdev=3Dhostnet0,id=3Dnet= 0,mac=3D52:54:00:89:5d:8b,bus=3Dpci.4,addr=3D0x1 -chardev pty,id=3Dcharseri= al0 -device isa-serial,chardev=3Dcharserial0,id=3Dserial0 -device usb-table= t,id=3Dinput0,bus=3Dusb.0,port=3D1 -vnc 0.0.0.0:0 -device cirrus-vga,id=3Dv= ideo0,vgamem_mb=3D8,bus=3Dpci.0,addr=3D0x12 -device virtio-balloon-pci,id= =3Dballoon0,bus=3Dpci.0,addr=3D0xd -msg timestamp=3Don >=20 > I am also very curious about this issue, in the linux kernel code, maybe = double check in function pci_bridge_check_ranges triggered this problem. If you can get the stacktrace in Linux when it tries to write this fffff value, that would be quite helpful. >=20 > >=20 > >=20 > >=20 > > > > > > > > > diff --git a/hw/pci/pci_bridge.c b/hw/pci/pci_bridge.c > > > > > > index b2e50c3..84b405d 100644 > > > > > > --- a/hw/pci/pci_bridge.c > > > > > > +++ b/hw/pci/pci_bridge.c > > > > > > @@ -256,7 +256,8 @@ void pci_bridge_write_config(PCIDevice *d, > > > > > > pci_default_write_config(d, address, val, len); > > > > > > - if (ranges_overlap(address, len, PCI_COMMAND, 2) || > > > > > > + if ( (val !=3D 0xffffffff) && > > > > > > + (ranges_overlap(address, len, PCI_COMMAND, 2) || > > > > > > /* io base/limit */ > > > > > > ranges_overlap(address, len, PCI_IO_BASE, 2) || > > > > > > @@ -266,7 +267,7 @@ void pci_bridge_write_config(PCIDevice *d, > > > > > > ranges_overlap(address, len, PCI_MEMORY_BASE, 20) || > > > > > > /* vga enable */ > > > > > > - ranges_overlap(address, len, PCI_BRIDGE_CONTROL, 2)) { > > > > > > + ranges_overlap(address, len, PCI_BRIDGE_CONTROL, 2))) { > > > > > > pci_bridge_update_mappings(s); > > > > > > } > > > > > > > > > > > > Thinks, > > > > > > Xu > > >