linux-kernel - Re: [PATCH v5 4/7] kvm, mem-hotplug: Reload L1' apic access page on migration in vcpu_enter

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Message-ID: <5411B3B3.900@redhat.com>
Date:	Thu, 11 Sep 2014 16:37:39 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Gleb Natapov <gleb@...nel.org>
CC:	Tang Chen <tangchen@...fujitsu.com>, mtosatti@...hat.com,
	nadav.amit@...il.com, jan.kiszka@....de, kvm@...r.kernel.org,
	laijs@...fujitsu.com, isimatu.yasuaki@...fujitsu.com,
	guz.fnst@...fujitsu.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 4/7] kvm, mem-hotplug: Reload L1' apic access page
 on migration in vcpu_enter_guest().

Il 11/09/2014 16:31, Gleb Natapov ha scritto:
>> > What if the page being swapped out is L1's APIC access page?  We don't
>> > run prepare_vmcs12 in that case because it's an L2->L0->L2 entry, so we
>> > need to "do something".
> We will do something on L2->L1 exit. We will call kvm_reload_apic_access_page().
> That is what patch 5 of this series is doing.

Sorry, I meant "the APIC access page prepared by L1" for L2's execution.

You wrote:

> if (!is_guest_mode() || !(vmcs12->secondary_vm_exec_control & ECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES))
>     write(PIC_ACCESS_ADDR)
> 
> In other words if L2 shares L1 apic access page then reload, otherwise do nothing.

but in that case you have to redo nested_get_page, so "do nothing"
doesn't work.

Paolo
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