Re: [PATCH 0/2] KVM: x86: Propagate AMD-specific IBRS bits to guests

[Takahiro Itazuri]

Date:   Tue, 28 Feb 2023 20:24:12 +0100
From:   Borislav Petkov <bp@xxxxxxxxx>
> I'd prefer if VMMs did supply whatever they prefer to the guests
> instead. None of those bits are used in the kernel for mitigations, as
> you've realized.

It is true that the kernel does not use those bits at all, but any
codes could be run inside guests.

One of examples is the following spectre/meltdown checker scipt used as
de facto standard.
https://github.com/speed47/spectre-meltdown-checker/blob/master/spectre-meltdown-checker.sh#L2768

Best regards,
Takahiro Itazuri