Re: "irq/matrix: Spread interrupts on allocation" breaks nouveau in mainline kernel

Lyude Paul
2018-01-24T20:02:05Z

On Wed, 2018-01-24 at 14:56 -0500, Lyude Paul wrote:
> On Wed, 2018-01-24 at 19:13 +0000, Ghannam, Yazen wrote:
> > > -----Original Message-----
> > > From: linux-kernel-owner@vger.kernel.org [mailto:linux-kernel-
> > > owner@vger.kernel.org] On Behalf Of Lyude Paul
> > > Sent: Wednesday, January 24, 2018 12:49 PM
> > > To: Thomas Gleixner <tglx@linutronix.de>
> > > Cc: hpa@zytor.com; keith.busch@intel.com; mingo@kernel.org; linux-
> > > kernel@vger.kernel.org
> > > Subject: Re: "irq/matrix: Spread interrupts on allocation" breaks
> > > nouveau
> > > in
> > > mainline kernel
> > >
> > > Hi, please ignore the warning: it happens before and after the
> > > regressing
> > > commit (I didn't actually mean to include it on the log I gave here,
> > > whoops).
> > > As for how I determined nouveau is getting assigned the same IRQ vector
> > > as
> > > another device, I checked using /sys/kernel/debug/irq. Additionally;
> > > when
> > > nouveau does initialize properly after resume (e.g. after reverting this
> > > patch) I see it get assigned a seperate vector from the other devices.
> > >
> >
> > +Boris. This thread seems to have split.
> >
> > Lyude,
> > Does the warning show on mainline or does it only show when bisecting?
> >
> > Sorry, I'm not sure what you mean by "it happens before and after the
> > regressing commit".
>
> Sorry about that! Let me clarify a little bit: this is a problem that shows
> up
> on mainline. Normally when we suspend the GPU in nouveau, we free the IRQs
> it's using before going into suspend
> (drivers/gpu/drm/nouveau/nvkm/subdev/pci/base.c:88), then reserve IRQs again
> on resume (drivers/gpu/drm/nouveau/nvkm/subdev/pci/base.c:134). Since this
> patch got pushed to mainline, the IRQ we get from request_irq() ends up
> having
> the same MSI vector as another device on the system:
>
> Before suspend, nouveau's IRQ allocation:
>
> handler: handle_edge_irq
> device: 0000:22:00.0
> status: 0x00000000
> istate: 0x00000000
> ddepth: 0
> wdepth: 0
> dstate: 0x01400200
> IRQD_ACTIVATED
> IRQD_IRQ_STARTED
> IRQD_SINGLE_TARGET
> node: 0
> affinity: 0-7
> effectiv: 1
> pending:
> domain: PCI-MSI-2
> hwirq: 0x1100000
> chip: PCI-MSI
> flags: 0x10
> IRQCHIP_SKIP_SET_WAKE
> parent:
> domain: VECTOR
> hwirq: 0x2f
> chip: APIC
> flags: 0x0
> Vector: 35
> Target: 1
>
> After resume and allocating the interrupt for nouveau again, we get a
> message
> from the kernel saying:
>
> [ 217.150787] do_IRQ: 1.35 No irq handler for vector
>
> As well, nouveau ends up getting no interrupts from the card and as a
> result
> fails to come back up:
>
> [ 219.153049] nouveau 0000:22:00.0: DRM: EVO timeout
> [ 220.226254] r8169 0000:1e:00.0 enp30s0: link up
> [ 221.153054] nouveau 0000:22:00.0: DRM: base-0: timeout
> [ 223.153528] nouveau 0000:22:00.0: DRM: base-0: timeout
>
> If we look through all of the other IRQ allocations, we'll find that now
> two
> devices have the MSI vector 35:
>
> nouveau:
> handler: handle_edge_irq
> device: 0000:22:00.0
> status: 0x00000000
> istate: 0x00000000
> ddepth: 0
> wdepth: 0
> dstate: 0x01400200
> IRQD_ACTIVATED
> IRQD_IRQ_STARTED
> IRQD_SINGLE_TARGET
> node: 0
> affinity: 0-7
> effectiv: 1
> pending:
> domain: PCI-MSI-2
> hwirq: 0x1100000
> chip: PCI-MSI
> flags: 0x10
> IRQCHIP_SKIP_SET_WAKE
> parent:
> domain: VECTOR
> hwirq: 0x2f
> chip: APIC
> flags: 0x0
> Vector: 35
> Target: 1
>
> and the PCI bridge (00:01.3 PCI bridge: Advanced Micro Devices, Inc.
> [AMD]
> Family 17h (Models 00h-0fh) PCIe GPP Bridge):
>
> handler: handle_edge_irq
> device: 0000:00:01.3
> status: 0x00000000
> istate: 0x00000000
> ddepth: 0
> wdepth: 0
> dstate: 0x03400200
> IRQD_ACTIVATED
> IRQD_IRQ_STARTED
> IRQD_SINGLE_TARGET
> node: 0
> affinity: 0-7
> effectiv: 0
> pending:
> domain: PCI-MSI-2
> hwirq: 0x5800
> chip: PCI-MSI
> flags: 0x10
> IRQCHIP_SKIP_SET_WAKE
> parent:
> domain: VECTOR
> hwirq: 0x19
> chip: APIC
> flags: 0x0
> Vector: 35
> Target: 0
>
> hope this helps clarify, I will keep looking at this from my end as well
> >
Almost forgot to mention: I came across this patch because reverting it
locally on the mainline kernel makes request_irq() behave normally (it doesn't
attempt to allocate the same vector twice anymore) and nouveau starts doing
suspend/resume correctly again
> >
> > Boris,
> > In any case, I like your idea on saving the block addresses. I can look
> > into
> > this.
> >
> > Thanks,
> > Yazen
--
Cheers,
Lyude Paul