linux-kernel - Re: [PATCH v2 12/13] iommu/vt-d: Add an irq

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Message-ID: <20240416151546.31a539e8@jacob-builder>
Date: Tue, 16 Apr 2024 15:15:46 -0700
From: Jacob Pan <jacob.jun.pan@...ux.intel.com>
To: "Tian, Kevin" <kevin.tian@...el.com>
Cc: LKML <linux-kernel@...r.kernel.org>, X86 Kernel <x86@...nel.org>, Peter
 Zijlstra <peterz@...radead.org>, "iommu@...ts.linux.dev"
 <iommu@...ts.linux.dev>, Thomas Gleixner <tglx@...utronix.de>, Lu Baolu
 <baolu.lu@...ux.intel.com>, "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
 "Hansen, Dave" <dave.hansen@...el.com>, Joerg Roedel <joro@...tes.org>, "H.
 Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>, Ingo Molnar
 <mingo@...hat.com>, "Luse, Paul E" <paul.e.luse@...el.com>, "Williams, Dan
 J" <dan.j.williams@...el.com>, Jens Axboe <axboe@...nel.dk>, "Raj, Ashok"
 <ashok.raj@...el.com>, "maz@...nel.org" <maz@...nel.org>,
 "seanjc@...gle.com" <seanjc@...gle.com>, Robin Murphy
 <robin.murphy@....com>, "jim.harris@...sung.com" <jim.harris@...sung.com>,
 "a.manzanares@...sung.com" <a.manzanares@...sung.com>, Bjorn Helgaas
 <helgaas@...nel.org>, "Zeng, Guang" <guang.zeng@...el.com>,
 "robert.hoo.linux@...il.com" <robert.hoo.linux@...il.com>,
 jacob.jun.pan@...ux.intel.com
Subject: Re: [PATCH v2 12/13] iommu/vt-d: Add an irq_chip for posted MSIs

Hi Kevin,

On Fri, 12 Apr 2024 09:36:10 +0000, "Tian, Kevin" <kevin.tian@...el.com>
wrote:

> > From: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> > Sent: Saturday, April 6, 2024 6:31 AM
> > 
> > + *
> > + * For the example below, 3 MSIs are coalesced into one CPU
> > notification. Only
> > + * one apic_eoi() is needed.
> > + *
> > + * __sysvec_posted_msi_notification()
> > + *	irq_enter();
> > + *		handle_edge_irq()
> > + *			irq_chip_ack_parent()
> > + *				dummy(); // No EOI
> > + *			handle_irq_event()
> > + *				driver_handler()
> > + *	irq_enter();
> > + *		handle_edge_irq()
> > + *			irq_chip_ack_parent()
> > + *				dummy(); // No EOI
> > + *			handle_irq_event()
> > + *				driver_handler()
> > + *	irq_enter();
> > + *		handle_edge_irq()
> > + *			irq_chip_ack_parent()
> > + *				dummy(); // No EOI
> > + *			handle_irq_event()
> > + *				driver_handler()  
> 
> typo: you added three irq_enter()'s here
right, will remove the middle two.

> 
> > + *	apic_eoi()
> > + * irq_exit()
> > + */
> > +static struct irq_chip intel_ir_chip_post_msi = {
> > +	.name			= "INTEL-IR-POST",
> > +	.irq_ack		= dummy,
> > +	.irq_set_affinity	= intel_ir_set_affinity,
> > +	.irq_compose_msi_msg	= intel_ir_compose_msi_msg,
> > +	.irq_set_vcpu_affinity	= intel_ir_set_vcpu_affinity,
> > +};  
> 
> What about putting this patch at end of the series (combining the
> change in intel_irq_remapping_alloc()) to finally enable this
> feature?
> 
> It reads slightly better to me to first get those callbacks extended
> to deal with the new mechanism (i.e. most changes in patch13)
> before using them in the new irqchip. 😊

makes sense, will do.

Thanks,

Jacob