GPU passthrough suddenly quit working

Hey all, I've got a strange problem today: Around 10:00 this morning, everything was working- my linux VM with its GPU passthrough was running great. I wanted to set up my Macinabox VM with passthrough as well, on the same card, so I turned everything off and tried it. That didn't work, so I restored all the configuration to the way it was. The end result, I think, is that a simple reboot seems to have made everything break. Both the hackintosh system I had been trying to make work and the Linux one that was working earlier (and has been working since december) have no video output. If the unraid server has just been rebooted, then either one will seem to take ownership of the GPU. It resets, but never displays anything. There is no error on startup, and there is no error in the log.

Here is the VM log for the linux system (looks the same for the macinabox except for disks):

-blockdev '{"driver":"file","filename":"/etc/libvirt/qemu/nvram/48cb9a59-fcd0-feba-d0fb-43229ba025b6_VARS-pure-efi.fd","node-name":"libvirt-pflash1-storage","auto-read-only":true,"discard":"unmap"}' \
-blockdev '{"node-name":"libvirt-pflash1-format","read-only":false,"driver":"raw","file":"libvirt-pflash1-storage"}' \
-machine pc-i440fx-4.2,accel=kvm,usb=off,dump-guest-core=off,mem-merge=off,pflash0=libvirt-pflash0-format,pflash1=libvirt-pflash1-format \
-cpu host,topoext=on,host-cache-info=on,l3-cache=off \
-m 8192 \
-overcommit mem-lock=off \
-smp 8,sockets=1,cores=8,threads=1 \
-uuid 48cb9a59-fcd0-feba-d0fb-43229ba025b6 \
-display none \
-no-user-config \
-nodefaults \
-chardev socket,id=charmonitor,fd=35,server,nowait \
-mon chardev=charmonitor,id=monitor,mode=control \
-rtc base=utc,driftfix=slew \
-global kvm-pit.lost_tick_policy=delay \
-no-hpet \
-no-shutdown \
-boot strict=on \
-device qemu-xhci,p2=15,p3=15,id=usb,bus=pci.0,addr=0x7 \
-device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x4 \
-blockdev '{"driver":"file","filename":"/mnt/user/domains/vorugal/vdisk1.img","node-name":"libvirt-2-storage","cache":{"direct":false,"no-flush":false},"auto-read-only":true,"discard":"unmap"}' \
-blockdev '{"node-name":"libvirt-2-format","read-only":false,"cache":{"direct":false,"no-flush":false},"driver":"raw","file":"libvirt-2-storage"}' \
-device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x3,drive=libvirt-2-format,id=virtio-disk2,bootindex=1,write-cache=on \
-blockdev '{"driver":"file","filename":"/mnt/user/isos/Solus-4.1-Plasma.iso","node-name":"libvirt-1-storage","auto-read-only":true,"discard":"unmap"}' \
-blockdev '{"node-name":"libvirt-1-format","read-only":true,"driver":"raw","file":"libvirt-1-storage"}' \
-device ide-cd,bus=ide.0,unit=0,drive=libvirt-1-format,id=ide0-0-0,bootindex=2 \
-netdev tap,fd=37,id=hostnet0,vhost=on,vhostfd=38 \
-device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:ab:1c:a5,bus=pci.0,addr=0x2 \
-chardev pty,id=charserial0 \
-device isa-serial,chardev=charserial0,id=serial0 \
-chardev socket,id=charchannel0,fd=40,server,nowait \
-device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=org.qemu.guest_agent.0 \
-device usb-tablet,id=input0,bus=usb.0,port=1 \
-device vfio-pci,host=0000:0a:00.0,id=hostdev0,bus=pci.0,addr=0x5 \
-device vfio-pci,host=0000:0b:00.3,id=hostdev1,bus=pci.0,addr=0x6 \
-sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \
-msg timestamp=on
2020-08-15 18:30:32.888+0000: Domain id=3 is tainted: high-privileges
2020-08-15 18:30:32.888+0000: Domain id=3 is tainted: host-cpu
char device redirected to /dev/pts/3 (label charserial0)

And here is the XML:

<?xml version='1.0' encoding='UTF-8'?>
<domain type='kvm' id='3'>
  <name>vorugal</name>
  <uuid>redacted</uuid>
  <metadata>
    <vmtemplate xmlns="unraid" name="Linux" icon="linux.png" os="linux"/>
  </metadata>
  <memory unit='KiB'>8388608</memory>
  <currentMemory unit='KiB'>8388608</currentMemory>
  <memoryBacking>
    <nosharepages/>
  </memoryBacking>
  <vcpu placement='static'>8</vcpu>
  <cputune>
    <vcpupin vcpu='0' cpuset='0'/>
    <vcpupin vcpu='1' cpuset='6'/>
    <vcpupin vcpu='2' cpuset='1'/>
    <vcpupin vcpu='3' cpuset='7'/>
    <vcpupin vcpu='4' cpuset='2'/>
    <vcpupin vcpu='5' cpuset='8'/>
    <vcpupin vcpu='6' cpuset='4'/>
    <vcpupin vcpu='7' cpuset='10'/>
  </cputune>
  <resource>
    <partition>/machine</partition>
  </resource>
  <os>
    <type arch='x86_64' machine='pc-i440fx-4.2'>hvm</type>
    <loader readonly='yes' type='pflash'>/usr/share/qemu/ovmf-x64/OVMF_CODE-pure-efi.fd</loader>
    <nvram>/etc/libvirt/qemu/nvram/48cb9a59-fcd0-feba-d0fb-43229ba025b6_VARS-pure-efi.fd</nvram>
  </os>
  <features>
    <acpi/>
    <apic/>
  </features>
  <cpu mode='host-passthrough' check='none'>
    <topology sockets='1' cores='8' threads='1'/>
    <cache mode='passthrough'/>
    <feature policy='require' name='topoext'/>
  </cpu>
  <clock offset='utc'>
    <timer name='rtc' tickpolicy='catchup'/>
    <timer name='pit' tickpolicy='delay'/>
    <timer name='hpet' present='no'/>
  </clock>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <devices>
    <emulator>/usr/local/sbin/qemu</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='raw' cache='writeback'/>
      <source file='/mnt/user/domains/vorugal/vdisk1.img' index='2'/>
      <backingStore/>
      <target dev='hdc' bus='virtio'/>
      <boot order='1'/>
      <alias name='virtio-disk2'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </disk>
    <disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <source file='/mnt/user/isos/Solus-4.1-Plasma.iso' index='1'/>
      <backingStore/>
      <target dev='hda' bus='ide'/>
      <readonly/>
      <boot order='2'/>
      <alias name='ide0-0-0'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>
    <controller type='usb' index='0' model='qemu-xhci' ports='15'>
      <alias name='usb'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
    </controller>
    <controller type='ide' index='0'>
      <alias name='ide'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
    </controller>
    <controller type='virtio-serial' index='0'>
      <alias name='virtio-serial0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
    </controller>
    <controller type='pci' index='0' model='pci-root'>
      <alias name='pci.0'/>
    </controller>
    <interface type='bridge'>
      <mac address='52:54:00:ab:1c:a5'/>
      <source bridge='br0'/>
      <target dev='vnet2'/>
      <model type='virtio'/>
      <alias name='net0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
    </interface>
    <serial type='pty'>
      <source path='/dev/pts/3'/>
      <target type='isa-serial' port='0'>
        <model name='isa-serial'/>
      </target>
      <alias name='serial0'/>
    </serial>
    <console type='pty' tty='/dev/pts/3'>
      <source path='/dev/pts/3'/>
      <target type='serial' port='0'/>
      <alias name='serial0'/>
    </console>
    <channel type='unix'>
      <source mode='bind' path='/var/lib/libvirt/qemu/channel/target/domain-3-vorugal/org.qemu.guest_agent.0'/>
      <target type='virtio' name='org.qemu.guest_agent.0' state='disconnected'/>
      <alias name='channel0'/>
      <address type='virtio-serial' controller='0' bus='0' port='1'/>
    </channel>
    <input type='tablet' bus='usb'>
      <alias name='input0'/>
      <address type='usb' bus='0' port='1'/>
    </input>
    <input type='mouse' bus='ps2'>
      <alias name='input1'/>
    </input>
    <input type='keyboard' bus='ps2'>
      <alias name='input2'/>
    </input>
    <hostdev mode='subsystem' type='pci' managed='yes'>
      <driver name='vfio'/>
      <source>
        <address domain='0x0000' bus='0x0a' slot='0x00' function='0x0'/>
      </source>
      <alias name='hostdev0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </hostdev>
    <hostdev mode='subsystem' type='pci' managed='yes'>
      <driver name='vfio'/>
      <source>
        <address domain='0x0000' bus='0x0b' slot='0x00' function='0x3'/>
      </source>
      <alias name='hostdev1'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
    </hostdev>
    <memballoon model='none'/>
  </devices>
  <seclabel type='dynamic' model='dac' relabel='yes'>
    <label>+0:+100</label>
    <imagelabel>+0:+100</imagelabel>
  </seclabel>
</domain>

Any ideas what's going on? This breaks exactly the same way with the GTX 760 that is currently in there (never tried it before) and the AMD R9 270 that was working for months before.

Getting the Linux system running is my primary objective- the OSX system was just for code testing.

Thanks for any help!