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

Borislav Petkov
2023-02-28T22:50:24Z

On Tue, Feb 28, 2023 at 10:24:16PM +0000, Takahiro Itazuri wrote:
> I'm still a kernel newbie and I don't have a strong opinion for that.
> I just thought it would be helpful if the KVM_GET_SUPPORTED_CPUID API
> returns the same security information as the host, as long as it is
> harmless.

Not harmless - cpufeatures.h should contain flags which the kernel uses
and not *every* CPUID bit out there.

If you want to advertize flags to guests, see
arch/x86/kvm/reverse_cpuid.h and the KVM-only feature flags. You can add
them there.

> https://documentation.suse.com/sles/15-SP1/html/SLES-all/cha-spectre.html

Well, I was against adding that to the documentation when I was at SUSE
but ...

--
Regards/Gruss,
Boris.