On 05/16/2012 10:13 AM, Sethi Varun-B16395 wrote: >>> Why is MSR[CE] unsafe? >> >> MSR=0 >> * critical interrupt comes in * >> mtmsr(MSR_CE) >> --> MSR == MSR_CE >> * interrupt should be delivered, but host doesn't get notified that >> MSR_CE is changing * >> >> However, we completely ignore critical interrupts in KVM these days, no? Watchdog will use them. > Well, it's least likely that MSR_CE/MSR_ME would get changed directly. They would > mostly get changed via rfci/rfmci, which would trap. It being unlikely means that there's little performance downside to this patch -- it doesn't mean that this patch is unnecessary. FWIW, Topaz directly manipulates MSR[CE] extensively, since it uses critical interrupts as its main interrupts (to distinguish from EE interrupts which are delivered directly to the guest). -Scott -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
