On 2013-03-11 18:23, Gleb Natapov wrote: > On Mon, Mar 11, 2013 at 04:36:33PM +0100, Jan Kiszka wrote: >> On 2013-03-11 15:23, Paolo Bonzini wrote: >>> Il 11/03/2013 15:05, Gleb Natapov ha scritto: >>>> On Mon, Mar 11, 2013 at 03:01:40PM +0100, Jan Kiszka wrote: >>>>>> We are not moving away from mp_state, we are moving away from using >>>>>> mp_state for signaling because with nested virt INIT does not always >>>>>> change mp_state, not only that it can change mp_state long after signal >>>>>> is received after vmx off is done. >>>>> >>>>> Right. >>>>> >>>>> BTW, for that to happen, we will also need to influence the INIT level. >>>>> Unless I misread the spec, INIT is blocked while in root mode, and if >>>>> you deassert INIT before leaving root (vmxoff, vmenter), nothing >>>>> actually happens. So what matters is the INIT signal level at the exit >>>>> of root mode. >>>>> >>>> You are talking about INIT# signal received via CPU pin, right? I think >>>> INIT send by IPI cannot go away. >>> >>> Neither can go away. For INIT sent by IPI, 10.4.7 says: >>> >>> Only the Pentium and P6 family processors support the INIT-deassert IPI. >>> An INIT-disassert IPI has no affect on the state of the APIC, other than >>> to reload the arbitration ID register with the value in the APIC ID >>> register. >>> >>> 18.27.1 also says that "In the local APIC, NMI and INIT (except for INIT >>> deassert) are always treated as edge triggered interrupts". >>> >>> >>> For INIT#, the ICH9 chipset says that "INIT# is driven low for 16 PCI >>> clocks" when a soft reset is requested. So we can guess that INIT# is >>> also edge-triggered. >> >> Ah, ok. So, virtually, INIT stays asserted until it can be delivered in >> form of a reset or a vmexit. >> > vmexit clears it? It has to. Otherwise, it would hit the host on vmxoff. The spec says: "The INIT signal is blocked whenever a logical processor is in VMX root operation. It is not blocked in VMX non-root operation. Instead, INITs cause VM exits [...]." Jan -- Siemens AG, Corporate Technology, CT RTC ITP SDP-DE Corporate Competence Center Embedded Linux -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
