Re: [PATCH v19 023/130] KVM: TDX: Initialize the TDX module when loading the KVM intel kernel module

[Binbin Wu]

On 3/15/2024 12:27 AM, Isaku Yamahata wrote:
> On Thu, Mar 14, 2024 at 10:05:35AM +0800,
> Binbin Wu <binbin.wu@xxxxxxxxxxxxxxx> wrote:
>
> > > diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
> > > index 18cecf12c7c8..18aef6e23aab 100644
> > > --- a/arch/x86/kvm/vmx/main.c
> > > +++ b/arch/x86/kvm/vmx/main.c
> > > @@ -6,6 +6,22 @@
> > >    #include "nested.h"
> > >    #include "pmu.h"
> > > +static bool enable_tdx __ro_after_init;
> > > +module_param_named(tdx, enable_tdx, bool, 0444);
> > > +
> > > +static __init int vt_hardware_setup(void)
> > > +{
> > > +	int ret;
> > > +
> > > +	ret = vmx_hardware_setup();
> > > +	if (ret)
> > > +		return ret;
> > > +
> > > +	enable_tdx = enable_tdx && !tdx_hardware_setup(&vt_x86_ops);
> > > +
> > > +	return 0;
> > > +}
> > > +
> > >    #define VMX_REQUIRED_APICV_INHIBITS				\
> > >    	(BIT(APICV_INHIBIT_REASON_DISABLE)|			\
> > >    	 BIT(APICV_INHIBIT_REASON_ABSENT) |			\
> > > @@ -22,6 +38,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
> > >    	.hardware_unsetup = vmx_hardware_unsetup,
> > > +	/* TDX cpu enablement is done by tdx_hardware_setup(). */
> > How about if there are some LPs that are offline.
> > In tdx_hardware_setup(), only online LPs are initialed for TDX, right?
> Correct.
>
>
> > Then when an offline LP becoming online, it doesn't have a chance to call
> > tdx_cpu_enable()?
> KVM registers kvm_online/offline_cpu() @ kvm_main.c as cpu hotplug callbacks.
> Eventually x86 kvm hardware_enable() is called on online/offline event.

Yes, hardware_enable() will be called when online,
but  hardware_enable() now is vmx_hardware_enable() right?
It doens't call tdx_cpu_enable() during the online path.