linux-kernel - Re: [RESEND PATCH 5/6] KVM: x86/VMX: add kvm_vmx_reinject_nmi

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Message-ID: <Y35yGltCxrwueOqn@google.com>
Date:   Wed, 23 Nov 2022 19:18:50 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     "Li, Xin3" <xin3.li@...el.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "bp@...en8.de" <bp@...en8.de>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "hpa@...or.com" <hpa@...or.com>,
        "Tian, Kevin" <kevin.tian@...el.com>
Subject: Re: [RESEND PATCH 5/6] KVM: x86/VMX: add kvm_vmx_reinject_nmi_irq()
 for NMI/IRQ reinjection

On Wed, Nov 23, 2022, Peter Zijlstra wrote:
> On Tue, Nov 22, 2022 at 08:52:35PM +0000, Sean Christopherson wrote:
> 
> > Another wart that needs to be addressed is trace_kvm_exit().  IIRC, tracepoints
> > must be outside of noinstr, though maybe I'm misremembering that.
> 
> You are not, that is correct. Another point to be careful with is usage
> of jump_label and static_call, both can be used in noinstr *provided*
> they don't actually ever change -- so boot time setup only.
> 
> If either of them were to change, text_poke_bp() has a clue in the name.

I think we're mostly ok on that front.  kvm_wait_lapic_expire() consumes multiple
static keys that can change at will, but that can be kept outside of the noinstr
section.  

Thanks!