linux-kernel - Re: [PATCH v4 0/6] kvm, mem-hotplug: Do not pin ept identity pagetable and apic access page.

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Message-ID: <540400B4.5050006@cn.fujitsu.com>
Date:	Mon, 1 Sep 2014 13:14:28 +0800
From:	tangchen <tangchen@...fujitsu.com>
To:	<gleb@...nel.org>, <mtosatti@...hat.com>, <nadav.amit@...il.com>,
	<jan.kiszka@....de>
CC:	<kvm@...r.kernel.org>, <laijs@...fujitsu.com>,
	<isimatu.yasuaki@...fujitsu.com>, <guz.fnst@...fujitsu.com>,
	<linux-kernel@...r.kernel.org>, <tangchen@...fujitsu.com>
Subject: Re: [PATCH v4 0/6] kvm, mem-hotplug: Do not pin ept identity pagetable
 and apic access page.

Hi Gleb,

Would you please help to review these patches ?

Thanks.

On 08/27/2014 06:17 PM, Tang Chen wrote:
> 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.
>
> [For ept identity page]
> Just do not pin it. When it is migrated, guest will be able to find the
> new page in the next ept violation.
>
> [For apic access page]
> The hpa of apic access page is stored in VMCS APIC_ACCESS_ADDR pointer.
> When apic access page is migrated, we update VMCS APIC_ACCESS_ADDR pointer
> for each vcpu in addition.
>
> NOTE: Tested with -cpu xxx,-x2apic option.
>        But since nested vm pins some other pages in memory, if user uses nested
>        vm, memory hot-remove will not work.
>
> Change log v3 -> v4:
> 1. The original patch 6 is now patch 5. ( by Jan Kiszka <jan.kiszka@....de> )
> 2. The original patch 1 is now patch 6 since we should unpin apic access page
>     at the very last moment.
>
>
> Tang Chen (6):
>    kvm: Use APIC_DEFAULT_PHYS_BASE macro as the apic access page address.
>    kvm: Remove ept_identity_pagetable from struct kvm_arch.
>    kvm: Make init_rmode_identity_map() return 0 on success.
>    kvm, mem-hotplug: Reload L1' apic access page on migration in
>      vcpu_enter_guest().
>    kvm, mem-hotplug: Reload L1's apic access page on migration when L2 is
>      running.
>    kvm, mem-hotplug: Do not pin apic access page in memory.
>
>   arch/x86/include/asm/kvm_host.h |   3 +-
>   arch/x86/kvm/svm.c              |  15 +++++-
>   arch/x86/kvm/vmx.c              | 103 +++++++++++++++++++++++++++-------------
>   arch/x86/kvm/x86.c              |  22 +++++++--
>   include/linux/kvm_host.h        |   3 ++
>   virt/kvm/kvm_main.c             |  30 +++++++++++-
>   6 files changed, 135 insertions(+), 41 deletions(-)
>

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