From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50056) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gWXcI-0000Jl-Kv for qemu-devel@nongnu.org; Mon, 10 Dec 2018 21:17:48 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gWXcD-0006nc-K0 for qemu-devel@nongnu.org; Mon, 10 Dec 2018 21:17:46 -0500 Received: from mx1.redhat.com ([209.132.183.28]:47214) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gWXcD-0006mt-AQ for qemu-devel@nongnu.org; Mon, 10 Dec 2018 21:17:41 -0500 Date: Mon, 10 Dec 2018 21:17:36 -0500 From: "Michael S. Tsirkin" Message-ID: <20181210205229-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> <20181210130650-mutt-send-email-mst@kernel.org> <7CECC2DFC21538489F72729DF5EFB4D908AC78EE@DGGEMM501-MBX.china.huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <7CECC2DFC21538489F72729DF5EFB4D908AC78EE@DGGEMM501-MBX.china.huawei.com> Content-Transfer-Encoding: quoted-printable 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 Tue, Dec 11, 2018 at 01:47:37AM +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 e= rror below: > > > > > > > > > > Unassigned mem write 00000000fc803004 =3D 0x1 > > > > > > > > > > > > > > > > > > > > memory-region: pci_bridge_pci > > > > > > > > > > 0000000000000000-ffffffffffffffff (prio 0, RW): pci_bridge_pc= i > > > > > > > > > > 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 00000000fda00000-00000000fdbffff= f > > > > > > > > > > 00000000fdc00000-00000000fddfffff (prio 1, RW): alias > > > > > pci_bridge_mem @pci_bridge_pci 00000000fdc00000-00000000fddffff= f > > > > > > > > > > 00000000fde00000-00000000fdffffff (prio 1, RW): alias > > > > > pci_bridge_mem @pci_bridge_pci 00000000fde00000-00000000fdfffff= f > > > > > > > > > > 00000000fe000000-00000000fe1fffff (prio 1, RW): alias > > > > > pci_bridge_mem @pci_bridge_pci 00000000fe000000-00000000fe1ffff= f > > > > > > > > > > 00000000fe200000-00000000fe3fffff (prio 1, RW): alias > > > > > pci_bridge_mem @pci_bridge_pci 00000000fe200000-00000000fe3ffff= f > > > > > > > > > > 00000000fe400000-00000000fe5fffff (prio 1, RW): alias > > > > > pci_bridge_mem @pci_bridge_pci 00000000fe400000-00000000fe5ffff= f > > > > > > > > > > 00000000fe600000-00000000fe7fffff (prio 1, RW): alias > > > > > pci_bridge_mem @pci_bridge_pci 00000000fe600000-00000000fe7ffff= f > > > > > > > > > > 00000000fe800000-00000000fe9fffff (prio 1, RW): alias > > > > > pci_bridge_mem @pci_bridge_pci 00000000fe800000-00000000fe9ffff= f > > > > > > > > > > fffffffffc800000-fffffffffc800000 (prio 1, RW): alias > > pci_bridge_pref_mem > > > > > @pci_bridge_pci fffffffffc800000-fffffffffc800000 <- Exceptio= nal Adress > > > > Space > > > > > > > > This one is empty though right? > > > > > > > > > > > > > > > > > > > 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 thi= s register. > > > > > > > > > > > > OK however as you show below the BAR being sized is the BAR if a > > > > bridge. Are you then adding a bridge device by hotplug? > > > > > > 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, th= is doesn't > > happened. > > > > > > > > > > > > > > > > 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] valu= e > > > > > -> 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 wro= ng > > > > > value > > > > > fffffffffc800000) > > > > > > > > > > -> > > > > > memory_region_transaction_commit > > > > > > > > > > > > > > > > > > > > So, as we can see, we use the wrong base address in qemu to upd= ate > > > > > the memory regions, though, we update the base address to > > > > > > > > > > The correct value after pci driver in VM write the original val= ue > > > > > 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. > > > > > > > > For sure. But I'm still puzzled as to why does Linux try to size = the > > > > BAR of the bridge while a device behind it is used. > > > > > > > > Can you pls post your QEMU command line? > > > > > > My QEMU command line: > > > /root/xyd/qemu-system-x86_64 -name guest=3DLinux,debug-threads=3Don= -S > > > -object > > > secret,id=3DmasterKey0,format=3Draw,file=3D/var/run/libvirt/qemu/do= main-194- > > > Linux/master-key.aes -machine > > > pc-i440fx-2.8,accel=3Dkvm,usb=3Doff,dump-guest-core=3Doff -cpu > > > host,+kvm_pv_eoi -bios /usr/share/OVMF/OVMF.fd -m > > > size=3D4194304k,slots=3D256,maxmem=3D33554432k -realtime mlock=3Dof= f -smp > > > 20,sockets=3D20,cores=3D1,threads=3D1 -numa node,nodeid=3D0,cpus=3D= 0-4,mem=3D1024 > > > -numa node,nodeid=3D1,cpus=3D5-9,mem=3D1024 -numa > > > node,nodeid=3D2,cpus=3D10-14,mem=3D1024 -numa > > > node,nodeid=3D3,cpus=3D15-19,mem=3D1024 -uuid > > > 34a588c7-b0f2-4952-b39c-47fae3411439 -no-user-config -nodefaults > > > -chardev > > > socket,id=3Dcharmonitor,path=3D/var/run/libvirt/qemu/domain-194-Lin= ux/moni > > > tor.sock,server,nowait -mon > > > chardev=3Dcharmonitor,id=3Dmonitor,mode=3Dcontrol -rtc base=3Dutc -= no-hpet > > > -global kvm-pit.lost_tick_policy=3Ddelay -no-shutdown -boot strict=3D= on > > > -device pci-bridge,chassis_nr=3D1,id=3Dpci.1,bus=3Dpci.0,addr=3D0x8= -device > > > pci-bridge,chassis_nr=3D2,id=3Dpci.2,bus=3Dpci.0,addr=3D0x9 -device > > > pci-bridge,chassis_nr=3D3,id=3Dpci.3,bus=3Dpci.0,addr=3D0xa -device > > > pci-bridge,chassis_nr=3D4,id=3Dpci.4,bus=3Dpci.0,addr=3D0xb -device > > > pci-bridge,chassis_nr=3D5,id=3Dpci.5,bus=3Dpci.0,addr=3D0xc -device > > > piix3-usb-uhci,id=3Dusb,bus=3Dpci.0,addr=3D0x1.0x2 -device > > > usb-ehci,id=3Dusb1,bus=3Dpci.0,addr=3D0x10 -device > > > nec-usb-xhci,id=3Dusb2,bus=3Dpci.0,addr=3D0x11 -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=3Dscsi2,bus=3Dpci.0,addr=3D0x5 -device > > > virtio-scsi-pci,id=3Dscsi3,bus=3Dpci.0,addr=3D0x6 -device > > > virtio-serial-pci,id=3Dvirtio-serial0,bus=3Dpci.0,addr=3D0x7 -drive > > > file=3D/mnt/sdb/xml/centos_74_x64_uefi.raw,format=3Draw,if=3Dnone,i= d=3Ddrive-v > > > irtio-disk0,cache=3Dnone -device > > > virtio-blk-pci,scsi=3Doff,bus=3Dpci.0,addr=3D0x2,drive=3Ddrive-virt= io-disk0,id > > > =3Dvirtio-disk0,bootindex=3D1 -drive > > > if=3Dnone,id=3Ddrive-ide0-1-1,readonly=3Don,cache=3Dnone -device > > > ide-cd,bus=3Dide.1,unit=3D1,drive=3Ddrive-ide0-1-1,id=3Dide0-1-1 -n= etdev > > > tap,fd=3D35,id=3Dhostnet0 -device > > > virtio-net-pci,netdev=3Dhostnet0,id=3Dnet0,mac=3D52:54:00:89:5d:8b,= bus=3Dpci.4 > > > ,addr=3D0x1 -chardev pty,id=3Dcharserial0 -device > > > isa-serial,chardev=3Dcharserial0,id=3Dserial0 -device > > > usb-tablet,id=3Dinput0,bus=3Dusb.0,port=3D1 -vnc 0.0.0.0:0 -device > > > cirrus-vga,id=3Dvideo0,vgamem_mb=3D8,bus=3Dpci.0,addr=3D0x12 -devic= e > > > virtio-balloon-pci,id=3Dballoon0,bus=3Dpci.0,addr=3D0xd -msg timest= amp=3Don > > > > > > 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. > >=20 > > If you can get the stacktrace in Linux when it tries to write this ff= fff value, that > > would be quite helpful. > >=20 >=20 > After I add mdelay(100) in function pci_bridge_check_ranges, this pheno= menon is > easier to reproduce, below is my modify in kernel: > diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c > index cb389277..86e232d 100644 > --- a/drivers/pci/setup-bus.c > +++ b/drivers/pci/setup-bus.c > @@ -27,7 +27,7 @@ > #include > #include > #include "pci.h" > - > +#include > unsigned int pci_flags; > =20 > struct pci_dev_resource { > @@ -787,6 +787,9 @@ static void pci_bridge_check_ranges(struct pci_bus = *bus) > pci_write_config_dword(bridge, PCI_PREF_BASE_UPPER32, > 0xffffffff); > pci_read_config_dword(bridge, PCI_PREF_BASE_UPPER32, &t= mp); > + mdelay(100); > + printk(KERN_ERR "sleep\n"); > + dump_stack(); > if (!tmp) > b_res[2].flags &=3D ~IORESOURCE_MEM_64; > pci_write_config_dword(bridge, PCI_PREF_BASE_UPPER32, > OK! I just sent a Linux patch that should help. I would appreciate it if you will give it a try and if that helps reply to it with a Tested-by: tag. --=20 MST