linux-kernel - Re: [PATCH v2 3/3] KVM: x86: Add a module param to control and enumerate device posted IRQs

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Message-ID: <Z9xWVkDx6hnpFw5Z@google.com>
Date: Thu, 20 Mar 2025 10:54:30 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Jim Mattson <jmattson@...gle.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Yosry Ahmed <yosry.ahmed@...ux.dev>
Subject: Re: [PATCH v2 3/3] KVM: x86: Add a module param to control and
 enumerate device posted IRQs

On Thu, Mar 20, 2025, Jim Mattson wrote:
> On Thu, Mar 20, 2025 at 7:31 AM Sean Christopherson <seanjc@...gle.com> wrote:
> >
> > Add a module param to allow disabling device posted interrupts without
> > having to sacrifice all of APICv/AVIC, and to also effectively enumerate
> > to userspace whether or not KVM may be utilizing device posted IRQs.
> > Disabling device posted interrupts is very desirable for testing, and can
> > even be desirable for production environments, e.g. if the host kernel
> > wants to interpose on device interrupts.
> 
> Are you referring to CONFIG_X86_POSTED_MSI, or something else that
> doesn't exist yet?

Yeah, that, and/or out-of-tree hackery to do similar coalescing (or ratelimiting).