Hi, Stefano,
Here is the calling graph that cause the bug:
unregister_real_device (ioemu)
|
+----> pt_msix_disable (ioemu)
|
+----> xc_domain_unbind_msi_irq (ioemu)
| |
| +----> do_domctl (xen) ----> arch_do_domctl (xen) ---->
pt_irq_destroy_bind_vtd (xen)
| |
| +----> unmap_domain_pirq_emuirq (xen) //freed
pirq_to_emuirq
|
+----> xc_physdev_unmap_pirq (ioemu)
|
+----> do_physdev_op (xen)
|
+----> physdev_unmap_pirq (xen)
|
+----> unmap_domain_pirq_emuirq (xen)
//found pirq_to_emuirq already freed, abort
|
+----> unmap_domain_pirq (xen) //not
called
The code path you mentioned is not taken for VF dev as its ptdev->machine_irq
is 0.
-----Original Message-----
From: Stefano Stabellini [mailto:stefano.stabellini@xxxxxxxxxxxxx]
Sent: Wednesday, January 26, 2011 7:11 PM
To: Zhang, Fengzhe
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-devel] [PATCH]vtd: Fix for irq bind failure after PCI
attaching 32 times
On Wed, 26 Jan 2011, Zhang, Fengzhe wrote:
> vtd: Fix for irq bind failure after PCI attaching 32 times
>
> Originally when detaching a PCI device, pirq_to_emuirq and pirq_to_irq are
> freed via hypercall do_physdev_op. Now in function pt_irq_destroy_bind_vtd,
> duplicated logic is added to free pirq_to_emuirq, but not pirq_to_irq. This
> causes do_physdev_op fail to free both emuirq and irq. After attaching a PCI
> device for 32 times, irq resources run out. This patch removes the redundant
> logic.
>
> Signed-off-by: Fengzhe Zhang <fengzhe.zhang@xxxxxxxxx>
>
It looks OK in principle, but if the theory is that we should always
call xc_physdev_unmap_pirq after xc_domain_unbind_pt_irq, I can find an
instance of xc_domain_unbind_pt_irq without any corresponding
xc_physdev_unmap_pirq.
Take a look at hw/pass-through.c:pt_reset_interrupt_and_io_mapping in
qemu:
if (ptdev->msi_trans_en == 0 && ptdev->machine_irq)
{
if (xc_domain_unbind_pt_irq(xc_handle, domid, ptdev->machine_irq,
PT_IRQ_TYPE_PCI, 0, e_device, e_intx, 0))
PT_LOG("Error: Unbinding of interrupt failed!\n");
}
but there is no following xc_physdev_unmap_pirq if MSI and MSIX are
disabled.
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