fix: pass only the gpu's iommu group and audio, not sibling psp/usb

scripts/gpu-passthrough.sh

@@ -57,6 +57,24 @@ group_members() {
     done
 }
 
+# The functions to hand to the guest with GPU $1: every device in its IOMMU group
+# (mandatory for vfio), plus any sibling function of the same PCI device that is
+# itself a display or HDMI/DP audio controller. An APU parks its PSP and USB
+# controllers on the same PCI device in separate IOMMU groups - those are the
+# host's, so siblings are filtered by class and never pulled in blindly.
+passthrough_devs() {
+    local d="$1" m cls
+    {
+        group_members "$d"
+        for m in "/sys/bus/pci/devices/${d%.*}".*; do
+            [ -e "$m" ] || continue
+            m=$(basename "$m")
+            cls=$(cat "/sys/bus/pci/devices/$m/class" 2>/dev/null)
+            case "$cls" in 0x03*|0x0403*) echo "$m";; esac
+        done
+    } | sort -u
+}
+
 driver_of() {
     local l
     l=$(readlink -f "/sys/bus/pci/devices/$1/driver" 2>/dev/null)
@@ -79,7 +97,7 @@ drives_display() {
 
 ids_of() {   # vendor:device for vfio-pci binding
     local d
-    for d in $(group_members "$1"); do
+    for d in $(passthrough_devs "$1"); do
         local cls; cls=$(cat "/sys/bus/pci/devices/$d/class" 2>/dev/null)
         # only real functions of the card: skip bridges (class 0x0604xx)
         case "$cls" in 0x0604*) continue;; esac
@@ -303,7 +321,7 @@ apply() {
     "$v" -c qemu:///system dumpxml --inactive "$dom" > "$backup/$dom.gpu-current.xml"
     grep -q 'ua-vfionative-gpu' "$backup/$dom.gpu-current.xml" || cp "$backup/$dom.gpu-current.xml" "$backup/$dom.before-gpu.xml"
     local devs="" m
-    for m in $( { group_members "$d"; ls -d "/sys/bus/pci/devices/${d%.*}".* | xargs -n1 basename; } | sort -u); do
+    for m in $(passthrough_devs "$d"); do
         case "$(cat "/sys/bus/pci/devices/$m/class" 2>/dev/null)" in 0x0604*) continue;; esac
         IFS=':.' read -r dm bs sl fn <<< "$m"
         devs+="    <hostdev mode='subsystem' type='pci' managed='yes'>\n      <source>\n"
@@ -330,7 +348,7 @@ xml() {
     echo "Add this to the domain, inside <devices>. Every device in the GPU's"
     echo "IOMMU group has to go together:"
     echo
-    for m in $(group_members "$d"); do
+    for m in $(passthrough_devs "$d"); do
         local cls; cls=$(cat "/sys/bus/pci/devices/$m/class" 2>/dev/null)
         case "$cls" in 0x0604*) continue;; esac
         IFS=':. ' read -r dom bus slot fn <<< "$(echo "$m" | tr ':.' '  ')"