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Date: Fri, 18 Jul 2014 17:05:20 +0800 From: Tang Chen <tangchen@...fujitsu.com> To: Gleb Natapov <gleb@...nel.org> CC: Jan Kiszka <jan.kiszka@....de>, <mtosatti@...hat.com>, <nadav.amit@...il.com>, <kvm@...r.kernel.org>, <laijs@...fujitsu.com>, <isimatu.yasuaki@...fujitsu.com>, <guz.fnst@...fujitsu.com>, <linux-kernel@...r.kernel.org> Subject: Re: [PATCH v2 5/5] kvm, mem-hotplug: Do not pin apic access page in memory. Hi Gleb, On 07/17/2014 09:57 PM, Gleb Natapov wrote: > On Thu, Jul 17, 2014 at 09:34:20PM +0800, Tang Chen wrote: >> Hi Gleb, >> >> On 07/15/2014 08:40 PM, Gleb Natapov wrote: >> ...... >>>> >>>> And yes, we have the problem you said here. We can migrate the page while L2 >>>> vm is running. >>>> So I think we should enforce L2 vm to exit to L1. Right ? >>>> >>> We can request APIC_ACCESS_ADDR reload during L2->L1 vmexit emulation, so >>> if APIC_ACCESS_ADDR changes while L2 is running it will be reloaded for L1 too. >>> >> >> Sorry, I think I don't quite understand the procedure you are talking about >> here. >> >> Referring to the code, I think we have three machines: L0(host), L1 and L2. >> And we have two types of vmexit: L2->L1 and L2->L0. Right ? >> >> We are now talking about this case: L2 and L1 shares the apic page. >> >> Using patch 5/5, when apic page is migrated on L0, mmu_notifier will notify >> L1, >> and update L1's VMCS. At this time, we are in L0, not L2. Why cannot we > Using patch 5/5, when apic page is migrated on L0, mmu_notifier will notify > L1 or L2 VMCS depending on which one happens to be running right now. > If it is L1 then L2's VMCS will be updated during vmentry emulation, OK, this is easy to understand. >if it is > L2 we need to request reload during vmexit emulation to make sure L1's VMCS is > updated. > I'm a little confused here. In patch 5/5, I called make_all_cpus_request() to force all vcpus exit to host. If we are in L2, where will the vcpus exit to ? L1 or L0 ? Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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