linux-kernel - Re: [RESEND PATCH 4/6] x86/traps: add external_interrupt() to dispatch external interrupts

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Message-ID: <Y21a0f8V5rxkJiXQ@google.com>
Date:   Thu, 10 Nov 2022 20:10:57 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     "Li, Xin3" <xin3.li@...el.com>
Cc:     "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>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "Tian, Kevin" <kevin.tian@...el.com>
Subject: Re: [RESEND PATCH 4/6] x86/traps: add external_interrupt() to
 dispatch external interrupts

On Thu, Nov 10, 2022, Li, Xin3 wrote:
> > > +__visible noinstr void external_interrupt(struct pt_regs *regs,
> > > +					  unsigned int vector)
> > > +{
> > > +	unsigned int sysvec = vector - FIRST_SYSTEM_VECTOR;
> > > +
> > > +	BUG_ON(vector < FIRST_EXTERNAL_VECTOR);
> > 
> > Why not return an error up the stack?  KVM and/or CPU bugs aren't unheard
> > of.
> > Dropping an IRQ obviously isn't ideal, but there's a non-zero chance that letting
> > KVM WARN and kill the VM will keep the host alive and thus other VMs
> > running.  A somewhat sophisticated setup might even react to the VM being
> > killed by migrating other VMs off the system and initiating host maintenance.
> 
> Make sense.
> 
> What about having it return a signed integer?

Ya, the standard 0/-errno will do nicely.