Description of problem:
Start vm, update vm memory hard_limit by "virsh memtune <domain> --hard-limit <n>" at run-time. Then check qemu process limit by "prlimit", the hard limit is not updated accordingly.
If I set hard_limit in vm xml when vm is shutoff, then start vm. The hard limit printed by prlimit will be same as the hard_limit setting in vm xml.
I'm not sure which one is expected, but the above two behaviors are not consistent.

Version-Release number of selected component:
libvirt-8.5.0-1.el9.x86_64
qemu-kvm-7.0.0-8.el9.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Start a vm

2. Check qemu process memory hard limit, it seems the default value is 64M if no hard_limit is set in vm xml:

1. prlimit -p `pidof qemu-kvm` -l
   RESOURCE DESCRIPTION SOFT HARD UNITS
   MEMLOCK max locked-in-memory address space 67108864 67108864 bytes

3. Update vm memory hard_limit:

1. virsh memtune uefi --hard-limit 262144
2. virsh memtune uefi
   hard_limit : 262144
   soft_limit : unlimited
   swap_hard_limit: unlimited
3. virsh dumpxml uefi |grep limit
   <hard_limit unit='KiB'>262144</hard_limit>

4. Check qemu process memory hard limit:

1. prlimit -p `pidof qemu-kvm` -l
   RESOURCE DESCRIPTION SOFT HARD UNITS
   MEMLOCK max locked-in-memory address space 67108864 67108864 bytes

Actual results:
As above