Re: [PATCH v5 7/8] KVM: nSVM: Advertise DecodeAssists to L1

[Jim Mattson]

On Mon, Aug 24, 2026 at 5:40 AM Tina Zhang <zhang_wei@xxxxxxxxxxxxxx> wrote:
>
> Advertise DecodeAssists to L1 now that KVM virtualizes the
> guest-visible DecodeAssist state in VMCB12: EXITINFO1 decode data for
> MOV CR/DR, INTn, and INVLPG exits, plus instruction bytes for nested
> page faults and intercepted #PF exits.  INVLPGA's linear address remains
> available directly from the saved guest rAX, as required by the APM.
>
> Expose the feature only when supported by hardware, as KVM still relies
> on hardware DecodeAssists for VM-Exits that are reflected directly from
> L2.
>
> With DecodeAssists exposed, QEMU configurations that require the feature
> (e.g. "-cpu ...,+decodeassists,...,enforce") are no longer rejected.
>
> Signed-off-by: Tina Zhang <zhang_wei@xxxxxxxxxxxxxx>

Once the implementation issues are addressed...

Reviewed-by: Jim Mattson <jmattson@xxxxxxxxxx>