Re: IRQ SMP affinity problems in domU with vcpus > 4 on HP ProLiant G6 with dual Xeon 5540 (Nehalem)

[Qing He <qing.he@intel.com>]

On Fri, 2009-10-16 at 17:41 +0800, Keir Fraser wrote:
> On 16/10/2009 09:35, "Zhang, Xiantao" <xiantao.zhang@intel.com> wrote:
> 
> >>> That maybe a problem if so. If a malicious/buggy guest won't EOI the
> >>> MSI vector, so host may hang due to lack of timeout mechanism?
> >> 
> >> Why does host hang? Only the assigned interrupt will block, and that's
> >> exactly what the guest wants :-)
> > 
> > Hypervisor shouldn't EOI the real vector until guest EOI the corresponding
> > virtual vector , right ?  Not sure.:-)
> 
> If the EOI is via the local APIC, which I suppose it must be, then a timeout
> fallback probably is required. This is because priorities are assigned
> arbitrarily to guest interrupts, and a non-EOIed interrupt blocks any
> lower-priority interrupts. In particular, some of those could be owned by
> dom0 for example, and be quite critical to forward progress of the entire
> system.

Yeah, I just come to realized it.

Thanks,
Qing