[MODERATED] Re: [PATCH v7 06/10] TAAv7 6

On Thu, Oct 24, 2019 at 10:53:16PM +0200, speck for Paolo Bonzini wrote:
> On the other hand, removing bits from CPUID or MSRs can cause issues
> even if TSX is not enabled in VMs.  Since most VMs won't have MDS_NO
> set, I think we should drop this patch for now.  After the embargo lifts
> we can add code to pass TSX_CTRL to the VM just like we do for
> SPEC_CTRL, including disabling TSX on vmentry/vmexit depending on guest
> CPUID.

TSX_CTRL is a slow MSR ... so if you do go this path you may also
want some heuristic to avoid switching a thread between guests that
have different settings for TSX.

-Tony