Re: [PATCH v4 5/9] KVM: arm64: vgic: move irq->get_input_level into an ops structure

From: Marc Zyngier <maz@kernel.org>
To: Alexandru Elisei <alexandru.elisei@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org,
	kvmarm@lists.cs.columbia.edu, James Morse <james.morse@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Eric Auger <eric.auger@redhat.com>,
	Hector Martin <marcan@marcan.st>,
	Mark Rutland <mark.rutland@arm.com>,
	Zenghui Yu <yuzenghui@huawei.com>,
	kernel-team@android.com
Subject: Re: [PATCH v4 5/9] KVM: arm64: vgic: move irq->get_input_level into an ops structure
Date: Tue, 22 Jun 2021 16:55:27 +0100	[thread overview]
Message-ID: <87zgvhc2s0.wl-maz@kernel.org> (raw)
In-Reply-To: <da762d7c-9eec-4fb8-ab6f-10bde6d777b3@arm.com>

On Tue, 15 Jun 2021 15:45:03 +0100,
Alexandru Elisei <alexandru.elisei@arm.com> wrote:
> 
> Hi Marc,
> 
> On 6/1/21 11:40 AM, Marc Zyngier wrote:
> > We already have the option to attach a callback to an interrupt
> > to retrieve its pending state. As we are planning to expand this
> > facility, move this callback into its own data structure.
> >
> > This will limit the size of individual interrupts as the ops
> > structures can be shared across multiple interrupts.
> 
> I can't figure out what you mean by that. If you are referring to
> struct vgic_irq, the change I am seeing is a pointer being replaced
> by another pointer, which shouldn't affect its size. Are you
> referring to something else?

Eventually, we have more than just a pointer (we also get flags in the
same structure), so this saves some space.

> 
> >
> > Signed-off-by: Marc Zyngier <maz@kernel.org>
> > ---
> >  arch/arm64/kvm/arch_timer.c |  8 ++++++--
> >  arch/arm64/kvm/vgic/vgic.c  | 14 +++++++-------
> >  include/kvm/arm_vgic.h      | 28 +++++++++++++++++-----------
> >  3 files changed, 30 insertions(+), 20 deletions(-)
> >
> > diff --git a/arch/arm64/kvm/arch_timer.c b/arch/arm64/kvm/arch_timer.c
> > index 74e0699661e9..e2288b6bf435 100644
> > --- a/arch/arm64/kvm/arch_timer.c
> > +++ b/arch/arm64/kvm/arch_timer.c
> > @@ -1116,6 +1116,10 @@ bool kvm_arch_timer_get_input_level(int vintid)
> >  	return kvm_timer_should_fire(timer);
> >  }
> >  
> > +static struct irq_ops arch_timer_irq_ops = {
> > +	.get_input_level = kvm_arch_timer_get_input_level,
> 
> Since kvm_arch_timer_get_input_level() is used only indirectly, through the
> get_input_level field of the static struct, I think we can make
> kvm_arch_timer_get_input_level() static and remove the declaration from
> include/kvm/arm_arch_timer.h.

Ah, good point. I'll stash a patch on top of the existing series (I'm
trying not to change what is currently queued in -next).

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.

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