Libvirt : host doesn't support passthrough of host PCI devices

Bonjour,

J’ai une machine sous Debian 11 avec un processeur AMD Ryzen 5 3400G sur lequel je veux faire tourner une machine virtuelle.
Le processeur a un processeur graphique intégré qui servira pour l’hôte, mais je souhaite utiliser une carte graphique pour la machine virtuelle.
Pour le moment, c’est un genre de prototypage, j’utilise donc une carte graphique NVIDIA Corporation GK208B [GeForce GT 710] qui traîne chez moi et dont je ne vais rien.
Pour configurer et lancer la machine virtuelle, j’utilise virt-manager qui se connecte au service libvirtd local. J’ai configuré une machine avec un passthrough USB sur un hub qui aura les périphériques d’entrée (clavier et souris) de la machine virtuelle et un passthrough PCI pour la carte graphique pour la sortie vidéo.
Pour information, voici quelques retours de commandes :

┌ (almtesh@Thorn + 0) (11/11/21 - 15:05:24) (1.72 - 0%) (~)
└% lspci -nn
00:00.0 Host bridge [0600]: Advanced Micro Devices, Inc. [AMD] Raven/Raven2 Root Complex [1022:15d0]
00:01.0 Host bridge [0600]: Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-1fh) PCIe Dummy Host Bridge [1022:1452]
00:01.1 PCI bridge [0604]: Advanced Micro Devices, Inc. [AMD] Raven/Raven2 PCIe GPP Bridge [6:0] [1022:15d3]
00:01.2 PCI bridge [0604]: Advanced Micro Devices, Inc. [AMD] Raven/Raven2 PCIe GPP Bridge [6:0] [1022:15d3]
00:08.0 Host bridge [0600]: Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-1fh) PCIe Dummy Host Bridge [1022:1452]
00:08.1 PCI bridge [0604]: Advanced Micro Devices, Inc. [AMD] Raven/Raven2 Internal PCIe GPP Bridge 0 to Bus A [1022:15db]
00:08.2 PCI bridge [0604]: Advanced Micro Devices, Inc. [AMD] Raven/Raven2 Internal PCIe GPP Bridge 0 to Bus B [1022:15dc]
00:14.0 SMBus [0c05]: Advanced Micro Devices, Inc. [AMD] FCH SMBus Controller [1022:790b] (rev 61)
00:14.3 ISA bridge [0601]: Advanced Micro Devices, Inc. [AMD] FCH LPC Bridge [1022:790e] (rev 51)
00:18.0 Host bridge [0600]: Advanced Micro Devices, Inc. [AMD] Raven/Raven2 Device 24: Function 0 [1022:15e8]
00:18.1 Host bridge [0600]: Advanced Micro Devices, Inc. [AMD] Raven/Raven2 Device 24: Function 1 [1022:15e9]
00:18.2 Host bridge [0600]: Advanced Micro Devices, Inc. [AMD] Raven/Raven2 Device 24: Function 2 [1022:15ea]
00:18.3 Host bridge [0600]: Advanced Micro Devices, Inc. [AMD] Raven/Raven2 Device 24: Function 3 [1022:15eb]
00:18.4 Host bridge [0600]: Advanced Micro Devices, Inc. [AMD] Raven/Raven2 Device 24: Function 4 [1022:15ec]
00:18.5 Host bridge [0600]: Advanced Micro Devices, Inc. [AMD] Raven/Raven2 Device 24: Function 5 [1022:15ed]
00:18.6 Host bridge [0600]: Advanced Micro Devices, Inc. [AMD] Raven/Raven2 Device 24: Function 6 [1022:15ee]
00:18.7 Host bridge [0600]: Advanced Micro Devices, Inc. [AMD] Raven/Raven2 Device 24: Function 7 [1022:15ef]
01:00.0 VGA compatible controller [0300]: NVIDIA Corporation GK208B [GeForce GT 710] [10de:128b] (rev a1)
01:00.1 Audio device [0403]: NVIDIA Corporation GK208 HDMI/DP Audio Controller [10de:0e0f] (rev a1)
02:00.0 USB controller [0c03]: Advanced Micro Devices, Inc. [AMD] 400 Series Chipset USB 3.1 XHCI Controller [1022:43d5] (rev 01)
02:00.1 SATA controller [0106]: Advanced Micro Devices, Inc. [AMD] 400 Series Chipset SATA Controller [1022:43c8] (rev 01)
02:00.2 PCI bridge [0604]: Advanced Micro Devices, Inc. [AMD] 400 Series Chipset PCIe Bridge [1022:43c6] (rev 01)
03:00.0 PCI bridge [0604]: Advanced Micro Devices, Inc. [AMD] 400 Series Chipset PCIe Port [1022:43c7] (rev 01)
03:01.0 PCI bridge [0604]: Advanced Micro Devices, Inc. [AMD] 400 Series Chipset PCIe Port [1022:43c7] (rev 01)
03:04.0 PCI bridge [0604]: Advanced Micro Devices, Inc. [AMD] 400 Series Chipset PCIe Port [1022:43c7] (rev 01)
03:05.0 PCI bridge [0604]: Advanced Micro Devices, Inc. [AMD] 400 Series Chipset PCIe Port [1022:43c7] (rev 01)
03:06.0 PCI bridge [0604]: Advanced Micro Devices, Inc. [AMD] 400 Series Chipset PCIe Port [1022:43c7] (rev 01)
03:07.0 PCI bridge [0604]: Advanced Micro Devices, Inc. [AMD] 400 Series Chipset PCIe Port [1022:43c7] (rev 01)
08:00.0 SATA controller [0106]: ASMedia Technology Inc. ASM1062 Serial ATA Controller [1b21:0612] (rev 02)
09:00.0 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller [10ec:8168] (rev 15)
0a:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Picasso [1002:15d8] (rev c8)
0a:00.1 Audio device [0403]: Advanced Micro Devices, Inc. [AMD/ATI] Raven/Raven2/Fenghuang HDMI/DP Audio Controller [1002:15de]
0a:00.2 Encryption controller [1080]: Advanced Micro Devices, Inc. [AMD] Family 17h (Models 10h-1fh) Platform Security Processor [1022:15df]
0a:00.3 USB controller [0c03]: Advanced Micro Devices, Inc. [AMD] Raven USB 3.1 [1022:15e0]
0a:00.4 USB controller [0c03]: Advanced Micro Devices, Inc. [AMD] Raven USB 3.1 [1022:15e1]
0a:00.6 Audio device [0403]: Advanced Micro Devices, Inc. [AMD] Family 17h (Models 10h-1fh) HD Audio Controller [1022:15e3]
0b:00.0 SATA controller [0106]: Advanced Micro Devices, Inc. [AMD] FCH SATA Controller [AHCI mode] [1022:7901] (rev 61)
┌ (almtesh@Thorn + 0) (11/11/21 - 15:05:27) (1.75 - 0%) (~)
└% grep -v "^#" /etc/apt/sources.list{,.d/*}
/etc/apt/sources.list:deb http://deb.debian.org/debian bullseye main contrib non-free
/etc/apt/sources.list:deb http://deb.debian.org/debian/ bullseye-updates main contrib non-free
/etc/apt/sources.list:deb http://deb.debian.org/debian-security bullseye-security main contrib non-free
/etc/apt/sources.list.d/signal.list:deb [arch=amd64] https://updates.signal.org/desktop/apt xenial main
┌ (almtesh@Thorn + 0) (11/11/21 - 15:05:30) (1.75 - 0%) (~)
└% groups
sudo man dialout fax voice cdrom floppy tape audio video plugdev input crontab bluetooth avahi pulse pulse-access scanner saned libvirt libvirt-qemu
┌ (almtesh@Thorn + 0) (11/11/21 - 15:05:42) (1.58 - 0%) (~)
└% cat /etc/modprobe.d/nouveau.conf 
blacklist nouveau
┌ (almtesh@Thorn + 0) (11/11/21 - 15:06:06) (1.42 - 0%) (~)
└% cat /etc/modprobe.d/vfio.conf   
options vfio_pci ids=10de:128b,10de:0e0f
┌ (almtesh@Thorn + 0) (11/11/21 - 15:06:11) (1.38 - 0%) (~)
└% cat /proc/cmdline 
BOOT_IMAGE=tftp://10.255.1.2//srv/netboot/systems/thorn-bullseye/vmlinuz ip=dhcp nfsroot=10.255.1.2:/srv/netboot/systems/thorn-bullseye root=/dev/nfs rw initrd=tftp://10.255.1.2//srv/netboot/systems/thorn-bullseye/initrd.img intel_iommu=on iommu=pt
┌ (almtesh@Thorn + 0) (11/11/21 - 15:06:27) (1.60 - 0%) (~)
└%

Et voici la configuration de la machine virtuelle :

<domain type="kvm">
  <name>VM</name>
  <uuid>600cc25b-2a02-4795-86d0-e5b816a713f9</uuid>
  <memory unit="KiB">4194304</memory>
  <currentMemory unit="KiB">4194304</currentMemory>
  <vcpu placement="static">4</vcpu>
  <os>
    <type arch="x86_64" machine="pc-i440fx-5.2">hvm</type>
    <boot dev="hd"/>
  </os>
  <features>
    <acpi/>
    <apic/>
    <vmport state="off"/>
  </features>
  <cpu mode="host-model" check="partial"/>
  <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>destroy</on_crash>
  <pm>
    <suspend-to-mem enabled="no"/>
    <suspend-to-disk enabled="no"/>
  </pm>
  <devices>
    <emulator>/usr/bin/qemu-system-x86_64</emulator>
    <controller type="usb" index="0" model="ich9-ehci1">
      <address type="pci" domain="0x0000" bus="0x00" slot="0x05" function="0x7"/>
    </controller>
    <controller type="usb" index="0" model="ich9-uhci1">
      <master startport="0"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x05" function="0x0" multifunction="on"/>
    </controller>
    <controller type="usb" index="0" model="ich9-uhci2">
      <master startport="2"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x05" function="0x1"/>
    </controller>
    <controller type="usb" index="0" model="ich9-uhci3">
      <master startport="4"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x05" function="0x2"/>
    </controller>
    <controller type="pci" index="0" model="pci-root"/>
    <interface type="network">
      <mac address="52:54:00:df:91:6c"/>
      <source network="default"/>
      <model type="virtio"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x03" function="0x0"/>
    </interface>
    <input type="mouse" bus="ps2"/>
    <input type="keyboard" bus="ps2"/>
    <sound model="ich6">
      <address type="pci" domain="0x0000" bus="0x00" slot="0x04" function="0x0"/>
    </sound>
    <hostdev mode="subsystem" type="usb" managed="yes">
      <source>
        <vendor id="0x05e3"/>
        <product id="0x0608"/>
      </source>
      <address type="usb" bus="0" port="1"/>
    </hostdev>
    <hostdev mode="subsystem" type="pci" managed="yes">
      <source>
        <address domain="0x0000" bus="0x01" slot="0x00" function="0x0"/>
      </source>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x0"/>
    </hostdev>
    <memballoon model="virtio">
      <address type="pci" domain="0x0000" bus="0x00" slot="0x07" function="0x0"/>
    </memballoon>
  </devices>
</domain>