Re: [PATCH v19 087/130] KVM: TDX: handle vcpu migration over logical processor

[Binbin Wu]

On 4/13/2024 12:15 AM, Reinette Chatre wrote:
> Hi Isaku,
>
> On 2/26/2024 12:26 AM, isaku.yamahata@xxxxxxxxx wrote:
> > From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> ...
>
> > @@ -218,6 +257,87 @@ static void tdx_reclaim_control_page(unsigned long td_page_pa)
> >   	free_page((unsigned long)__va(td_page_pa));
> >   }
> >   
> > +struct tdx_flush_vp_arg {
> > +	struct kvm_vcpu *vcpu;
> > +	u64 err;
> > +};
> > +
> > +static void tdx_flush_vp(void *arg_)
> > +{
> > +	struct tdx_flush_vp_arg *arg = arg_;
> > +	struct kvm_vcpu *vcpu = arg->vcpu;
> > +	u64 err;
> > +
> > +	arg->err = 0;
> > +	lockdep_assert_irqs_disabled();
> > +
> > +	/* Task migration can race with CPU offlining. */
> > +	if (unlikely(vcpu->cpu != raw_smp_processor_id()))
> > +		return;
> > +
> > +	/*
> > +	 * No need to do TDH_VP_FLUSH if the vCPU hasn't been initialized.  The
> > +	 * list tracking still needs to be updated so that it's correct if/when
> > +	 * the vCPU does get initialized.
> > +	 */
> > +	if (is_td_vcpu_created(to_tdx(vcpu))) {
> > +		/*
> > +		 * No need to retry.  TDX Resources needed for TDH.VP.FLUSH are,
> > +		 * TDVPR as exclusive, TDR as shared, and TDCS as shared.  This
> > +		 * vp flush function is called when destructing vcpu/TD or vcpu
> > +		 * migration.  No other thread uses TDVPR in those cases.
> > +		 */
Is it possible that other thread uses TDR or TDCS as exclusive?

> >