Re: [PATCH] KVM: x86: Fix the initial value of mcg_cap

[Sean Christopherson]

On Thu, Oct 20, 2022, Xiaoyao Li wrote:
> vcpu->arch.mcg_cap represents the value of MSR_IA32_MCG_CAP. It's
> set via ioctl(KVM_X86_SETUP_MCE) from userspace when exposing and
> configuring MCE to guest.
> 
> It's wrong to leave the default value as KVM_MAX_MCE_BANKS.

Why?  I agree it's an odd default, but the whole MCE API is odd.  Functionally,
I don't see anything that's broken by allowing the guest to access the MCx_CTL MSRs
by default.