Support PCI path style for rd.qubes.* kernel param

Support stable identifiers (as listed by qvm-pci) also for hiding
specific devices manually. Classic BDF format is (and will remain)
still supported.
This covers rd.qubes.hide_pci and rd.qubes.dom0_usb options.

To properly handle all the cases (like old identifier in one one option
but new in the other) translate all devices to BDF before comparing.

QubesOS/qubes-issues#8681

Author: marmarek

dracut/modules.d/90qubes-pciback/qubes-pciback.sh

@@ -3,6 +3,38 @@
 type getarg >/dev/null 2>&1 || . /lib/dracut-lib.sh
 unset re HIDE_PCI usb_in_dom0 dev skip exposed
 
+resolve_dev() {
+    local dev="$1"
+    local segment="0000"
+    local bridge bus bus_offset
+
+    case "$dev" in
+        # device path to resolve
+        [0-9a-f][0-9a-f][0-9a-f][0-9a-f]_*_*.*)
+            segment=${dev%%_*}
+            dev="${dev#*_}"
+            ;;
+        *_*.*) ;;
+        # (S)BDF directly
+        *:*:*.*) echo "$dev"; return ;;
+        *:*.*) echo "0000:$dev"; return;;
+        *) echo "Invalid device format: $dev" >&2; return ;;
+    esac
+
+    while [[ "$dev" = *-* ]]; do
+        bridge="${dev%%-*}"
+        bridge="${bridge//_/:}"
+        dev="${dev#*-}"
+        # this is in hex
+        bus="${dev%%_*}"
+        # this is in dec
+        bus_offset=$(<"/sys/bus/pci/devices/$segment:$bridge/secondary_bus_number") || return
+        bus=$(printf "%02x" $(( "0x$bus" + bus_offset )) )
+        dev="${bus}_${dev#*_}"
+    done
+    echo "$segment:${dev//_/:}"
+}
+
 usb_in_dom0=false
 
 if getargbool 0 rd.qubes.hide_all_usb; then
@@ -22,17 +54,17 @@ HIDE_PCI=$(set -o pipefail; { lspci -mm -n | awk "/^[^ ]* \"$re/ {print \$1}";})
 
 manual_pcidevs=$(getarg rd.qubes.hide_pci)
 case $manual_pcidevs in
-(*[!0-9a-f.:,]*) warn 'Bogus rd.qubes.hide_pci option - fix your kernel command line!';;
+(*[!0-9a-f_.:,-]*) warn 'Bogus rd.qubes.hide_pci option - fix your kernel command line!';;
 esac
 HIDE_PCI="$HIDE_PCI ${manual_pcidevs//,/ }"
 
 # XXX should this be fatal?
 ws=$' \n'
-[[ $HIDE_PCI =~ ^[0-9a-f.:$ws]+$ ]] ||
+[[ $HIDE_PCI =~ ^[0-9a-f_.:$ws-]+$ ]] ||
     die 'Bogus PCI device list - fix your kernel command line!'
 modprobe xen-pciback 2>/dev/null || :
 dom0_usb=$(getarg rd.qubes.dom0_usb)
-if [[ "$dom0_usb" == *[!0-9a-f.:,]* ]] ; then
+if [[ "$dom0_usb" == *[!0-9a-f_.:,-]* ]] ; then
     warn 'Bogus rd.qubes.dom0_usb option - fix your kernel command line!'
     dom0_usb=""
 elif [ -n "$dom0_usb" ] ; then
@@ -44,12 +76,16 @@ fi
 set -e
 # ... and hide them so that Dom0 doesn't load drivers for them
 for dev in $HIDE_PCI; do
+    BDF=$(resolve_dev "$dev")
+    if [ -z "$BDF" ]; then
+        die "Cannot find device '$dev' to hide"
+    fi
     skip=false
     for exposed in $dom0_usb; do
-        if [ "$dev" = "$exposed" ]; then skip=true; fi
+        exposed=$(resolve_dev "$exposed")
+        if [ "$BDF" = "$exposed" ]; then skip=true; fi
     done
     if [ "$skip" = true ]; then continue; fi
-    BDF=0000:$dev
     if [ -e "/sys/bus/pci/devices/$BDF/driver" ]; then
         echo -n "$BDF" > "/sys/bus/pci/devices/$BDF/driver/unbind"
     fi