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

Binbin Wu
2024-03-15T04:44:53Z

On 3/15/2024 12:27 AM, Isaku Yamahata wrote:
> On Thu, Mar 14, 2024 at 10:05:35AM +0800,
> Binbin Wu <binbin.wu@linux.intel.com> 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.