Description of problem:
As subject

Version-Release number of selected component (if applicable):
libvirt-8.3.0-1.el9.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Emulate pmem and mmcblk by QEMU. And check these node devices
i. Start a RHEL9 VM with these XML:
<domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
<maxMemory slots='16' unit='KiB'>4097152</maxMemory>
...
<cpu mode='host-model' check='partial'>
<numa>
<cell id='0' cpus='0-1' memory='2095104' unit='KiB'/>
</numa>
</cpu>
...
<devices>
...
<memory model='virtio-pmem' access='shared'>
<source>
<path>/tmp/virtio_pmem</path>
</source>
<target>
<size unit='KiB'>524288</size>
</target>
<address type='pci' domain='0x0000' bus='0x00' slot='0x0a' function='0x0'/>
</memory>
</devices>
<qemu:commandline>
<qemu:arg value='-device'/>
<qemu:arg value='sdhci-pci,id=sdhci,bus=pci.0,addr=0xf'/>
<qemu:arg value='-device'/>
<qemu:arg value='sd-card,drive=mydrive'/>
<qemu:arg value='-drive'/>
<qemu:arg value='id=mydrive,if=none,format=raw,file=/tmp/sdcard'/>
</qemu:commandline>

ii. Check the block:
[root@localhost ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
mmcblk0 179:0 0 128M 0 disk
vda 252:0 0 10G 0 disk
├─vda1 252:1 0 1G 0 part /boot
└─vda2 252:2 0 9G 0 part
├─rhel-root 253:0 0 8G 0 lvm /
└─rhel-swap 253:1 0 1G 0 lvm [SWAP]
pmem0 259:0 0 511.9M 1 disk

[root@localhost ~]# udevadm info --name mmcblk0
P: /devices/pci0000:00/0000:00:0f.0/mmc_host/mmc0/mmc0:4567/block/mmcblk0
N: mmcblk0
L: 0
S: disk/by-id/mmc-QEMU__0xdeadbeef
E: DEVPATH=/devices/pci0000:00/0000:00:0f.0/mmc_host/mmc0/mmc0:4567/block/mmcblk0
E: DEVNAME=/dev/mmcblk0
E: DEVTYPE=disk
E: DISKSEQ=3
E: MAJOR=179
E: MINOR=0
E: SUBSYSTEM=block
E: USEC_INITIALIZED=15106162
E: ID_SERIAL=0xdeadbeef
E: ID_NAME=QEMU_
E: DEVLINKS=/dev/disk/by-id/mmc-QEMU__0xdeadbeef
E: TAGS=:systemd:
E: CURRENT_TAGS=:systemd:

[root@localhost ~]# udevadm info --name pmem0
P: /devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0012:00/ndbus0/region0/namespace0.0/block/pmem0
N: pmem0
L: 0
E: DEVPATH=/devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0012:00/ndbus0/region0/namespace0.0/block/pmem0
E: DEVNAME=/dev/pmem0
E: DEVTYPE=disk
E: DISKSEQ=2
E: MAJOR=259
E: MINOR=0
E: SUBSYSTEM=block
E: USEC_INITIALIZED=14732010
E: TAGS=:systemd:
E: CURRENT_TAGS=:systemd:

iii. Check the node devices:
[root@localhost ~]# virsh nodedev-list --cap storage
block_vda

No mmcblk and peme devices.

2. For mtdblock device, since the kernel config of RHEL9(5.14.0-90.el9.x86_64) is "CONFIG_MTD=m, CONFIG_MTD_BLOCK=m, CONFIG_MTD_RAM not set. It cannot emulated by kernel in RHEL9. So I test it on Fedora rawhide(5.17.4-300.fc36.x86_64, libvirt-8.3.0-1.fc37.x86_64)
i. Emulate mtdblock device

1. modprobe mtdram total_size=200 erase_size=100
2. modprobe mtdblock

ii. Check mtdblock by lsblk, udev and virsh.
➜ ~ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
mtdblock0 31:0 0 200K 0 disk
vda 252:0 0 80G 0 disk
└─vda1 252:1 0 80G 0 part /
vdb 252:16 0 5G 0 disk /mnt

➜ ~ udevadm info --name mtdblock0
P: /devices/virtual/mtd/mtd0/mtdblock0
M: mtdblock0
R: 0
U: block
T: disk
D: b 31:0
N: mtdblock0
L: 0
Q: 11
E: DEVPATH=/devices/virtual/mtd/mtd0/mtdblock0
E: DEVNAME=/dev/mtdblock0
E: DEVTYPE=disk
E: DISKSEQ=11
E: MAJOR=31
E: MINOR=0
E: SUBSYSTEM=block
E: USEC_INITIALIZED=1724723462880
E: TAGS=:systemd:
E: CURRENT_TAGS=:systemd:

➜ ~ virsh nodedev-list --cap storage
block_vda_230c9ab9_9ea9_433d_8
block_vdb

No mtdblock listed by virsh.

Actual results:
As above

Expected results:
Libvirt node device could list mtdblock, mmcblk, pmem devices.

Additional info:
See also: Bug 2045953 - 'virsh nodedev-list --cap storage' doesn't list host nvme storage