linux-kernel - Re: [PATCH 0/4] kvm, mem-hotplug: Do not pin ept identity pagetable and apic access page.

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Message-ID: <20140703060409.GL18167@minantech.com>
Date:	Thu, 3 Jul 2014 09:04:10 +0300
From:	Gleb Natapov <gleb@...nel.org>
To:	Tang Chen <tangchen@...fujitsu.com>
Cc:	mtosatti@...hat.com, kvm@...r.kernel.org, laijs@...fujitsu.com,
	isimatu.yasuaki@...fujitsu.com, guz.fnst@...fujitsu.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/4] kvm, mem-hotplug: Do not pin ept identity pagetable
 and apic access page.

On Thu, Jul 03, 2014 at 09:17:59AM +0800, Tang Chen wrote:
> Hi Gleb,
> 
> On 07/02/2014 05:00 PM, Tang Chen wrote:
> >Hi Gleb, Marcelo,
> >
> >Please help to review this patch-set.
> >
> >NOTE: This patch-set doesn't work properly.
> >
> >
> >ept identity pagetable and apic access page in kvm are pinned in memory.
> >As a result, they cannot be migrated/hot-removed.
> >
> >But actually they don't need to be pinned in memory.
> >
> >This patch-set introduces two new vcpu requests: KVM_REQ_MIGRATE_EPT and KVM_REQ_MIGRATE_APIC.
> >These two requests are made when the two pages are migrated by the mmu_notifier
> >to reset the related variable to unusable value. And will also be made when
> >ept violation happens to reset new pages.
> >
> >
> >[Known problem]
> >After this patch-set applied, the two pages can be migrated/hot-removed.
> >But after migrating apic access page, the guest died.
> >
> >The host physical address of apic access page is stored in VMCS. I reset
> >it to 0 to stop guest from accessing it when it is unmapped by
> >kvm_mmu_notifier_invalidate_page(). And reset it to new page's host physical
> >address in tdp_page_fault(). But it seems that guest will access apic page
> >directly by the host physical address.
> 
> Would you please to give some advice about this problem ?
> 
I haven't reviewed third patch yet, will do ASAP.

--
			Gleb.
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