[Qemu-devel] [Bug 1465935] Re: kvm_irqchip_commit_routes: Assertion `ret == 0' failed

[Li Chengyuan]

-----Original Message-----
From: Paolo Bonzini [mailto:address@hidden 
Sent: 2015年7月1日 21:39
To: Li, Chengyuan
Cc: address@hidden
Subject: Re: [Qemu-devel] [PATCH] Fix irq route entries exceed 
KVM_MAX_IRQ_ROUTES

On 30/06/2015 05:47, Li, Chengyuan wrote:
> Here is my understanding,
> 
> 1) why isn't the existing check in kvm_irqchip_get_virq enough to fix 
> the bug?
> 
> From kvm_pc_setup_irq_routing() function, we can see that 15 routes 
> from PIC and 23 routes from IOAPIC are added into irq route table, but 
> only
> 23 irq(gsi) are reserved. This leads to irq route table has been full 
> but there are still 15 free gsi. So the "retry" part of
> kvm_irqchip_get_virq() shall never have chance to be executed.
> 
> 2) If you introduce this extra call to kvm_flush_dynamic_msi_routes, 
> does the existing check become obsolete?
> 
> As gsi_count is the max number of irq route table, if below code is 
> merged, then existing check is obsolete and can be removed.
> 
> +    if (!s->direct_msi && s->irq_routes->nr == s->gsi_count) {
> +        kvm_flush_dynamic_msi_routes(s);
> +    }
> 
> Please let me know if you have some other comments for the patch? Thanks!

Thanks for finally clearing up my doubts about the patch!  I'll apply it
soon.

Paolo

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https://bugs.launchpad.net/bugs/1465935

Title:
  kvm_irqchip_commit_routes: Assertion `ret == 0' failed

Status in QEMU:
  New
Status in qemu package in Ubuntu:
  Incomplete

Bug description:
  Several my QEMU instances crashed, and in the  qemu log, I can see
  this assertion failure,

     qemu-system-x86_64: /build/buildd/qemu-2.0.0+dfsg/kvm-all.c:984:
  kvm_irqchip_commit_routes: Assertion `ret == 0' failed.

  The QEMU version is 2.0.0, HV OS is ubuntu 12.04, kernel 3.2.0-38.
  Guest OS is RHEL 6.3.

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