Re: [Xen-devel] [PATCH] Dont call msi_unmap_pirq() if did not enabled msi

[Joe Jin <joe.jin@xxxxxxxxxx>]

On 2009-11-17 07:59, Jan Beulich wrote:
> >>> Joe Jin <joe.jin@xxxxxxxxxx> 17.11.09 01:19 >>>
> >--- a/drivers/pci/msi-xen.c  Fri Oct 23 10:07:22 2009 +0100
> >+++ b/drivers/pci/msi-xen.c  Tue Nov 17 08:16:42 2009 +0800
> >@@ -673,6 +673,12 @@
> >     if (!pos)
> >             return;
> > 
> >+    if (!(dev->msi_enabled)) {
> >+            printk(KERN_INFO "PCI: %s: Device did not enabled MSI.\n",
> >+                   pci_name(dev));
> >+            return;
> >+    }
> >+ 
> >     pirq = dev->irq;
> >     /* Restore dev->irq to its default pin-assertion vector */
> >     dev->irq = msi_dev_entry->default_irq;
> 
> But shouldn't this happen before the CONFIG_XEN_PCIDEV_FRONTEND
> conditional block? This one also calls evtchn_map_pirq(..., 0), i.e. would
> also result in the storing of no_irq_chip.

However when irq_desc[irq]->chip set to no_irq_chip, if any device try to 
request
the @irq will failed and return -ENOSYS via request_irq()->setup_irq().

According to codes, only when CONFIG_XEN_PCIDEV_FRONTEND and 
!is_initial_xendomain(),
it will called evtchn_map_pirq(), meant only guest OS may call it, Dom0 will 
not.
But during pci_enable_msi(), it never set the flag(dev->msi_enabled), I'm not 
sure if
Guest OS will set it if enabled msi, any suggestion?

Thanks,
Joe


> 
> Jan
> 
> 



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