Re: [PATCH 1/5] KVM: x86: fix presentation of TSX feature in ARCH_CAPABILITIES

[Jim Mattson]

On Mon, Nov 18, 2019 at 10:17 AM Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:
>
> KVM does not implement MSR_IA32_TSX_CTRL, so it must not be presented
> to the guests.  It is also confusing to have !ARCH_CAP_TSX_CTRL_MSR &&
> !RTM && ARCH_CAP_TAA_NO: lack of MSR_IA32_TSX_CTRL suggests TSX was not
> hidden (it actually was), yet the value says that TSX is not vulnerable
> to microarchitectural data sampling.  Fix both.

I actually think kvm should virtualize IA32_TSX_CTRL for VMs that have
exclusive use of their cores (i.e. the same VMs for which we disable
MWAIT and HLT exiting).