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Date:   Fri, 11 Nov 2022 13:48:26 +0100
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Subject: Re: [RESEND PATCH 5/6] KVM: x86/VMX: add kvm_vmx_reinject_nmi_irq()
 for NMI/IRQ reinjection
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To:     Peter Zijlstra <peterz@infradead.org>
Cc:     "Li, Xin3" <xin3.li@intel.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "x86@kernel.org" <x86@kernel.org>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "tglx@linutronix.de" <tglx@linutronix.de>,
        "mingo@redhat.com" <mingo@redhat.com>,
        "bp@alien8.de" <bp@alien8.de>,
        "dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
        "hpa@zytor.com" <hpa@zytor.com>,
        "Christopherson,, Sean" <seanjc@google.com>,
        "Tian, Kevin" <kevin.tian@intel.com>
References: <20221110061545.1531-1-xin3.li@intel.com>
 <20221110061545.1531-6-xin3.li@intel.com>
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 <6097036e-063f-5175-72b2-8935b12af853@redhat.com>
 <Y24908NWCdzUNqI0@hirez.programming.kicks-ass.net>
From:   Paolo Bonzini <pbonzini@redhat.com>
In-Reply-To: <Y24908NWCdzUNqI0@hirez.programming.kicks-ass.net>
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On 11/11/22 13:19, Peter Zijlstra wrote:
> On Fri, Nov 11, 2022 at 01:04:27PM +0100, Paolo Bonzini wrote:
>> On Intel you can optionally make it hold onto IRQs, but NMIs are always
>> eaten by the VMEXIT and have to be reinjected manually.
> 
> That 'optionally' thing worries me -- as in, KVM is currently
> opting-out?

Yes, because "If the “process posted interrupts” VM-execution control is 
1, the “acknowledge interrupt on exit” VM-exit control is 1" (SDM 
26.2.1.1, checks on VM-Execution Control Fields).  Ipse dixit.  Posted 
interrupts are available and used on all processors since I think Ivy 
Bridge.

(sorry about splitting the replies across two threads)

Paolo