Re: [RFC PATCH v1 10/15] KVM: VMX: Use WRMSRNS or its immediate form when available

[H. Peter Anvin]

On April 11, 2025 9:32:32 PM PDT, Xin Li <xin@xxxxxxxxx> wrote:
>On 4/11/2025 2:12 PM, Jim Mattson wrote:
>> Surely, any CPU that has WRMSRNS also supports "Virtualize
>> IA32_SPEC_CTRL," right? Shouldn't we be using that feature rather than
>> swapping host and guest values with some form of WRMSR?
>
>Good question, the simple answer is that they are irrelevant.

Also, *in this specific case* IA32_SPEC_CTRL is architecturally nonserializing, i.e. WRMSR executes as WRMSRNS anyway.