Re: [RFC PATCH v2 65/69] KVM: X86: Introduce initial_tsc_khz in struct kvm_arch

[Sean Christopherson]

On Tue, Jul 06, 2021, Paolo Bonzini wrote:
> On 03/07/21 00:05, isaku.yamahata@xxxxxxxxx wrote:
> > From: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
> > 
> > Introduce a per-vm variable initial_tsc_khz to hold the default tsc_khz
> > for kvm_arch_vcpu_create().
> > 
> > This field is going to be used by TDX since TSC frequency for TD guest
> > is configured at TD VM initialization phase.
> > 
> > Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
> > Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> > ---
> >   arch/x86/include/asm/kvm_host.h | 1 +
> >   arch/x86/kvm/x86.c              | 3 ++-
> >   2 files changed, 3 insertions(+), 1 deletion(-)
> 
> So this means disabling TSC frequency scaling on TDX.  Would it make sense
> to delay VM creation to a separate ioctl, similar to KVM_ARM_VCPU_FINALIZE
> (KVM_VM_FINALIZE)?

There's an equivalent of that in the next mega-patch, the KVM_TDX_INIT_VM sub-ioctl
of KVM_MEMORY_ENCRYPT_OP.  The TSC frequency for the guest gets provided at that
time.