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Message-ID: <5470a429-cbbd-4946-b11a-ab86380d9b68@linux.intel.com>
Date: Fri, 15 Mar 2024 12:44:46 +0800
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Subject: Re: [PATCH v19 023/130] KVM: TDX: Initialize the TDX module when
 loading the KVM intel kernel module
To: Isaku Yamahata <isaku.yamahata@intel.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
 isaku.yamahata@gmail.com, Paolo Bonzini <pbonzini@redhat.com>,
 erdemaktas@google.com, Sean Christopherson <seanjc@google.com>,
 Sagi Shahar <sagis@google.com>, Kai Huang <kai.huang@intel.com>,
 chen.bo@intel.com, hang.yuan@intel.com, tina.zhang@intel.com,
 isaku.yamahata@linux.intel.com
References: <cover.1708933498.git.isaku.yamahata@intel.com>
 <f028d43abeadaa3134297d28fb99f283445c0333.1708933498.git.isaku.yamahata@intel.com>
 <f5da22e3-55fd-4e8b-8112-ccf1468012c8@linux.intel.com>
 <20240314162712.GO935089@ls.amr.corp.intel.com>
From: Binbin Wu <binbin.wu@linux.intel.com>
In-Reply-To: <20240314162712.GO935089@ls.amr.corp.intel.com>
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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.