linux-kernel - Re: [PATCH] x86, irq: Keep IRQ assignment for PCI devices during suspend/hibernation, bisected

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Date:	Fri, 01 Aug 2014 20:27:23 +0800
From:	Jiang Liu <jiang.liu@...ux.intel.com>
To:	Borislav Petkov <bp@...en8.de>
CC:	"Rafael J . Wysocki" <rjw@...ysocki.net>,
	Thomas Gleixner <tglx@...utronix.de>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	linux-pci@...r.kernel.org, lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86, irq: Keep IRQ assignment for PCI devices during
 suspend/hibernation, bisected


On 2014/8/1 18:56, Borislav Petkov wrote:
> Ok,
> 
> so I went and looked at tip and which branches could be the usual
> suspects. And whaddya know, tip/x86/apic was the first to pick and it
> contained the culprit:
> 
> 6a38fa0e3c94 ("x86, irq, ACPI: Release IOAPIC pin when PCI device is disabled")
Hi Borislav,
	The above commit may cause failure of suspend/hiberrnation.
The reason is:
1) With recent changers, we dynamically allocate irq number for IOAPIC
   pins.
2) The allocated irq will be released when suspending/hibernating.
	pci_disable_device()->pcibios_disable_irq()
3) When resuming, a different irq may be assigned to the PCI device.
	pci_enable_device()->pcibios_enable_irq()
4) Now the hardware will deliver interrupt to the new allocated irq
   but the interrupt handler is still registered on old irq, so it
   breaks the driver and causes failure of hibernation.

The patch sent out by me is to fix this issue by keeping the allocated
irq when suspend/hibernate. And seems it works as expected.

But I still don't know why it causes IOMMU related warnings as:
AMD-Vi: Event logged [IO_PAGE_FAULT device=00:12.0 domain=0x0009
address=0x0000000000000000 flags=0x0000]

Regards!
Gerry
> 
> It seems like my machine doesn't like releasing the IOAPIC pin. Or,
> maybe it is IOMMU-related and the IOMMU doesn't like this releasing of
> the pin *after* the device gets suspended and *before* the IOMMU.
> 
> Strange.
> 
> Oh well, a well deserved lunch now :)
> 
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