The missing extensions have to be added to variable kvm_isa_ext_arr[] in
arch/riscv/kvm/isa.c.

I don't think any further KVM changes are needed:

Zicclsm
Mandates that the main memory system must functionally support misaligned load 
and store operations.
KVM: Pass-through. Handled directly by physical hardware execution; KVM just 
exposes the support flag.

Ziccamoa
Mandates that all cacheable and coherent main memory regions must fully support 
all atomic memory operations (AMOs) from the 'A' extension.
KVM: Pass-through. Enforced by the host physical memory bus and cache 
hierarchy; no KVM code emulation required.

Ziccif
Guarantees that main memory supports instruction fetching with atomicity 
requirements (crucial for dynamic code modification).
KVM Pass-through. Dictated by physical cache-coherency behaviors; KVM exposes 
this state passively.

Za64rs
Guarantees that the hardware's reservation set (used by 
Load-Reserved/Store-Conditional LR/SC instructions) is naturally aligned and a 
maximum of 64 bytes.
KVM: Pass-through. This is an inherent property of the physical CPU's 
cache-tracking mechanics; KVM exposes the layout to the guest.

Next action:

Send a patch upstream for review.

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https://bugs.launchpad.net/bugs/2170634

Title:
  On 7.3.0-9-generic does not fully support RVA23U64

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