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From: Gleb Natapov <gleb@kernel.org>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>,
	mtosatti@redhat.com, nadav.amit@gmail.com, jan.kiszka@web.de,
	kvm@vger.kernel.org, laijs@cn.fujitsu.com,
	isimatu.yasuaki@jp.fujitsu.com, guz.fnst@cn.fujitsu.com,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 4/7] kvm, mem-hotplug: Reload L1' apic access page on migration in vcpu_enter_guest().
Date: Thu, 11 Sep 2014 17:47:16 +0300	[thread overview]
Message-ID: <20140911144716.GF26540@minantech.com> (raw)
In-Reply-To: <5411B3B3.900@redhat.com>

On Thu, Sep 11, 2014 at 04:37:39PM +0200, Paolo Bonzini wrote:
> 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.
> 
Ah, 7/7 is new in this submission. Before that this page was still
pinned.  Looking at 7/7 now I do not see how it can work since it has no
code for mmu notifier to detect that it deals with such page and call
kvm_reload_apic_access_page().  I said to Tang previously that nested
kvm has a bunch of pinned page that are hard to deal with and suggested
to iron out non nested case first :(

--
			Gleb.

  reply	other threads:[~2014-09-11 14:53 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-11  5:37 [PATCH v5 0/7] kvm, mem-hotplug: Do not pin ept identity pagetable and apic access page Tang Chen
2014-09-11  5:38 ` [PATCH v5 1/7] kvm: Use APIC_DEFAULT_PHYS_BASE macro as the apic access page address Tang Chen
2014-09-11  9:10   ` Paolo Bonzini
2014-09-11  5:38 ` [PATCH v5 2/7] kvm: Remove ept_identity_pagetable from struct kvm_arch Tang Chen
2014-09-11  9:14   ` Paolo Bonzini
2014-09-11  5:38 ` [PATCH v5 3/7] kvm: Make init_rmode_identity_map() return 0 on success Tang Chen
2014-09-11  9:17   ` Paolo Bonzini
2014-09-11 10:26     ` tangchen
2014-09-11  5:38 ` [PATCH v5 4/7] kvm, mem-hotplug: Reload L1' apic access page on migration in vcpu_enter_guest() Tang Chen
2014-09-11  9:21   ` Paolo Bonzini
2014-09-11 10:12     ` Gleb Natapov
2014-09-11 10:47       ` Paolo Bonzini
2014-09-11 11:30         ` Gleb Natapov
2014-09-11 13:05           ` Paolo Bonzini
2014-09-11 13:59             ` Gleb Natapov
2014-09-11 14:06               ` Paolo Bonzini
2014-09-11 14:21                 ` Gleb Natapov
2014-09-11 14:24                   ` Paolo Bonzini
2014-09-11 14:31                     ` Gleb Natapov
2014-09-11 14:37                       ` Paolo Bonzini
2014-09-11 14:47                         ` Gleb Natapov [this message]
2014-09-12  3:32                           ` tangchen
2014-09-12  3:36                     ` tangchen
2014-09-11 10:20     ` tangchen
2014-09-11 10:39       ` Paolo Bonzini
2014-09-11  5:38 ` [PATCH v5 5/7] kvm, mem-hotplug: Reload L1's apic access page on migration when L2 is running Tang Chen
2014-09-11  9:28   ` Paolo Bonzini
2014-09-11  5:38 ` [PATCH v5 6/7] kvm, mem-hotplug: Unpin and remove kvm_arch->apic_access_page Tang Chen
2014-09-11  9:34   ` Paolo Bonzini
2014-09-11  5:38 ` [PATCH v5 7/7] kvm, mem-hotplug: Unpin and remove nested_vmx->apic_access_page Tang Chen
2014-09-11  9:33   ` Paolo Bonzini
2014-09-11  9:43     ` tangchen

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