Re: [Xen-devel] [PATCH] x86/vMSI-X: Fix host crash when shutting down guests with MSI capable devices

[George Dunlap <dunlapg@xxxxxxxxx>]

On Thu, Jul 21, 2016 at 11:18 AM, Andrew Cooper
<andrew.cooper3@xxxxxxxxxx> wrote:
> c/s 74c6dc2d "x86/vMSI-X: defer intercept handler registration" caused MSI-X
> table infrastructure not to always be initialised, but it missed one path
> which needed an is-initialised check.
>
> If a devices is passed through to a domain which is MSI capable but not MSI-X
> capable, the call to msixtbl_init() is omitted, but a XEN_DOMCTL_unbind_pt_irq
> hypercall still calls into msixtbl_pt_unregister().  This follows the linked
> list pointer which is still NULL.
>
> Introduce an is-initalised check to msixtbl_pt_unregister().
>
> Furthermore, the purpose of the open-coded msixtbl_list.next check is rather
> subtle.  Introduce an msixtbl_initialised() predicate instead, which makes its
> purpose far more obvious.

Thanks for this bit.

> Reported-by: Sander Eikelenboom <linux@xxxxxxxxxxxxxx>
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Reviewed-by: George Dunlap <george.dunlap@xxxxxxxxxx>

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