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Date: Tue, 23 Apr 2024 21:15:34 +0800
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Subject: Re: [PATCH v19 085/130] KVM: TDX: Complete interrupts after tdexit
To: Reinette Chatre <reinette.chatre@intel.com>, 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
References: <cover.1708933498.git.isaku.yamahata@intel.com>
 <aa6a927214a5d29d5591a0079f4374b05a82a03f.1708933498.git.isaku.yamahata@intel.com>
 <7d19f693-d8e9-4a9d-8cfa-3ec9c388622f@intel.com>
From: Binbin Wu <binbin.wu@linux.intel.com>
In-Reply-To: <7d19f693-d8e9-4a9d-8cfa-3ec9c388622f@intel.com>
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On 4/17/2024 2:23 AM, Reinette Chatre wrote:
> Hi Isaku,
>
> (In shortlog "tdexit" can be "TD exit" to be consistent with
> documentation.)
>
> On 2/26/2024 12:26 AM, isaku.yamahata@intel.com wrote:
>> From: Isaku Yamahata <isaku.yamahata@intel.com>
>>
>> This corresponds to VMX __vmx_complete_interrupts().  Because TDX
>> virtualize vAPIC, KVM only needs to care NMI injection.
> This seems to be the first appearance of NMI and the changelog
> is very brief. How about expending it with:
>
> "This corresponds to VMX __vmx_complete_interrupts().  Because TDX
>   virtualize vAPIC, KVM only needs to care about NMI injection.
   ^
   virtualizes

Also, does it need to mention that non-NMI interrupts are handled by 
posted-interrupt mechanism?

For example:

"This corresponds to VMX __vmx_complete_interrupts().  Because TDX
  virtualizes vAPIC, and non-NMI interrupts are delivered using 
posted-interrupt
  mechanism, KVM only needs to care about NMI injection.
..
"

>
>   KVM can request TDX to inject an NMI into a guest TD vCPU when the
>   vCPU is not active. TDX will attempt to inject an NMI as soon as
>   possible on TD entry. NMI injection is managed by writing to (to
>   inject NMI) and reading from (to get status of NMI injection)
>   the PEND_NMI field within the TDX vCPU scope metadata (Trust
>   Domain Virtual Processor State (TDVPS)).
>
>   Update KVM's NMI status on TD exit by checking whether a requested
>   NMI has been injected into the TD. Reading the metadata via SEAMCALL
>   is expensive so only perform the check if an NMI was injected.
>
>   This is the first need to access vCPU scope metadata in the
>   "management" class. Ensure that needed accessor is available.
> "
>