[RFC v4 0/2] memory: Delete assertion in memory_region_unregister_iommu_notifier

[Eugenio Pérez]

I am able to hit this assertion when a Red Hat 7 guest virtio_net device
raises an "Invalidation" of all the TLB entries. This happens in the
guest's startup if 'intel_iommu=on' argument is passed to the guest
kernel and right IOMMU/ATS devices are declared in qemu's command line.

Command line:
/home/qemu/x86_64-softmmu/qemu-system-x86_64 -name \
guest=rhel7-test,debug-threads=on -machine \
pc-q35-5.1,accel=kvm,usb=off,dump-guest-core=off,kernel_irqchip=split \
-cpu \
Broadwell,vme=on,ss=on,vmx=on,f16c=on,rdrand=on,hypervisor=on,arat=on,tsc-adjust=on,umip=on,arch-capabilities=on,xsaveopt=on,pdpe1gb=on,abm=on,skip-l1dfl-vmentry=on,rtm=on,hle=on
 \
-m 8096 -realtime mlock=off -smp 2,sockets=2,cores=1,threads=1 -uuid \
d022ecbf-679e-4755-87ce-eb87fc5bbc5d -display none -no-user-config \
-nodefaults -rtc base=utc,driftfix=slew -global \
kvm-pit.lost_tick_policy=delay -no-hpet -no-shutdown -global \
ICH9-LPC.disable_s3=1 -global ICH9-LPC.disable_s4=1 -boot strict=on \
-device intel-iommu,intremap=on,device-iotlb=on -device \
pcie-root-port,port=0x8,chassis=1,id=pci.1,bus=pcie.0,multifunction=on,addr=0x1 
\
-device \
pcie-root-port,port=0x9,chassis=2,id=pci.2,bus=pcie.0,addr=0x1.0x1 \
-device \
pcie-root-port,port=0xa,chassis=3,id=pci.3,bus=pcie.0,addr=0x1.0x2 \
-device \
pcie-root-port,port=0xb,chassis=4,id=pci.4,bus=pcie.0,addr=0x1.0x3 \
-device \
pcie-root-port,port=0xc,chassis=5,id=pci.5,bus=pcie.0,addr=0x1.0x4 \
-device \
pcie-root-port,port=0xd,chassis=6,id=pci.6,bus=pcie.0,addr=0x1.0x5 \
-device \
pcie-root-port,port=0xe,chassis=7,id=pci.7,bus=pcie.0,addr=0x1.0x6 \
-device qemu-xhci,p2=15,p3=15,id=usb,bus=pci.2,addr=0x0 -device \
virtio-serial-pci,id=virtio-serial0,bus=pci.3,addr=0x0 -drive \
file=/home/virtio-test2.qcow2,format=qcow2,if=none,id=drive-virtio-disk0 \
-device \
virtio-blk-pci,scsi=off,bus=pci.4,addr=0x0,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1
 \
-netdev tap,id=hostnet0,vhost=on,vhostforce=on -device \
virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:0d:1d:f2,bus=pci.1,addr=0x0,iommu_platform=on,ats=on
 \
-device virtio-balloon-pci,id=balloon0,bus=pci.5,addr=0x0 -object \
rng-random,id=objrng0,filename=/dev/urandom -device \
virtio-rng-pci,rng=objrng0,id=rng0,bus=pci.6,addr=0x0 -s -msg \
timestamp=on

#0  0x00007ffff521370f in raise () at /lib64/libc.so.6
#1  0x00007ffff51fdb25 in abort () at /lib64/libc.so.6
#2  0x00007ffff51fd9f9 in _nl_load_domain.cold.0 () at /lib64/libc.so.6
#3  0x00007ffff520bcc6 in .annobin_assert.c_end () at /lib64/libc.so.6
#4  0x0000555555888171 in memory_region_notify_one
(notifier=0x7ffde0487fa8, entry=0x7ffde5dfe200) at
/home/qemu/memory.c:1918
#5  0x0000555555888247 in memory_region_notify_iommu
(iommu_mr=0x555556f6c0b0, iommu_idx=0, entry=...) at
/home/qemu/memory.c:1941
#6  0x0000555555951c8d in vtd_process_device_iotlb_desc
(s=0x555557609000, inv_desc=0x7ffde5dfe2d0)
    at /home/qemu/hw/i386/intel_iommu.c:2468
#7  0x0000555555951e6a in vtd_process_inv_desc (s=0x555557609000) at
/home/qemu/hw/i386/intel_iommu.c:2531
#8  0x0000555555951fa5 in vtd_fetch_inv_desc (s=0x555557609000) at
/home/qemu/hw/i386/intel_iommu.c:2563
#9  0x00005555559520e5 in vtd_handle_iqt_write (s=0x555557609000) at
/home/qemu/hw/i386/intel_iommu.c:2590
#10 0x0000555555952b45 in vtd_mem_write (opaque=0x555557609000,
addr=136, val=2688, size=4) at /home/qemu/hw/i386/intel_iommu.c:2837
#11 0x0000555555883e17 in memory_region_write_accessor
    (mr=0x555557609330, addr=136, value=0x7ffde5dfe478, size=4,
shift=0, mask=4294967295, attrs=...) at /home/qemu/memory.c:483
#12 0x000055555588401d in access_with_adjusted_size
    (addr=136, value=0x7ffde5dfe478, size=4, access_size_min=4,
access_size_max=8, access_fn=
    0x555555883d38 <memory_region_write_accessor>, mr=0x555557609330,
attrs=...) at /home/qemu/memory.c:544
#13 0x0000555555886f37 in memory_region_dispatch_write
(mr=0x555557609330, addr=136, data=2688, op=MO_32, attrs=...)
    at /home/qemu/memory.c:1476
#14 0x0000555555827a03 in flatview_write_continue
    (fv=0x7ffdd8503150, addr=4275634312, attrs=...,
ptr=0x7ffff7ff0028, len=4, addr1=136, l=4, mr=0x555557609330) at
/home/qemu/exec.c:3146
#15 0x0000555555827b48 in flatview_write (fv=0x7ffdd8503150,
addr=4275634312, attrs=..., buf=0x7ffff7ff0028, len=4)
    at /home/qemu/exec.c:3186
#16 0x0000555555827e9d in address_space_write
    (as=0x5555567ca640 <address_space_memory>, addr=4275634312,
attrs=..., buf=0x7ffff7ff0028, len=4) at /home/qemu/exec.c:3277
#17 0x0000555555827f0a in address_space_rw
    (as=0x5555567ca640 <address_space_memory>, addr=4275634312,
attrs=..., buf=0x7ffff7ff0028, len=4, is_write=true)
    at /home/qemu/exec.c:3287
#18 0x000055555589b633 in kvm_cpu_exec (cpu=0x555556b65640) at
/home/qemu/accel/kvm/kvm-all.c:2511
#19 0x0000555555876ba8 in qemu_kvm_cpu_thread_fn (arg=0x555556b65640)
at /home/qemu/cpus.c:1284
#20 0x0000555555dafff1 in qemu_thread_start (args=0x555556b8c3b0) at
util/qemu-thread-posix.c:521
#21 0x00007ffff55a62de in start_thread () at /lib64/libpthread.so.0
#22 0x00007ffff52d7e83 in clone () at /lib64/libc.so.6

(gdb) frame 4
#4  0x0000555555888171 in memory_region_notify_one
(notifier=0x7ffde0487fa8, entry=0x7ffde5dfe200) at
/home/qemu/memory.c:1918
1918        assert(entry->iova >= notifier->start && entry_end <=
notifier->end);
(gdb) p *entry
$1 = {target_as = 0x555556f6c050, iova = 0, translated_addr = 0,
addr_mask = 18446744073709551615, perm = IOMMU_NONE}
--

Tested with vhost-net, with a linux bridge to forward packets.
Forwarding with vhostuser interfaces + dpdk-testpmd io forwarding mode seems
broken also in v5.1.0-rc3.

v4: Rename IOMMU_NOTIFIER_IOTLB -> IOMMU_NOTIFIER_DEVIOTLB.
    Make vhost-net notifier just IOMMU_NOTIFIER_DEVIOTLB, not
    IOMMU_NOTIFIER_UNMAP

v3: Skip the assertion in case notifier is a IOTLB one, since they can manage
    arbitrary ranges. Using a flag in the notifier for now, as Peter suggested.

v2: Actually delete assertion instead of just commenting out using C99

Eugenio Pérez (2):
  memory: Rename memory_region_notify_one to
    memory_region_notify_one_iommu
  memory: Skip bad range assertion if notifier is DEVIOTLB type

 hw/arm/smmu-common.c  |  2 +-
 hw/arm/smmuv3.c       |  2 +-
 hw/i386/intel_iommu.c |  4 ++--
 hw/virtio/vhost.c     |  2 +-
 include/exec/memory.h |  8 +++++---
 softmmu/memory.c      | 21 ++++++++++++++++-----
 6 files changed, 26 insertions(+), 13 deletions(-)

-- 
2.18.1