linux-kernel - Re: [PATCH v8 0/8] kvm, mem-hotplug: Do not pin ept identity pagetable and apic access page.

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Message-ID: <5423D015.6090107@cn.fujitsu.com>
Date:	Thu, 25 Sep 2014 16:19:33 +0800
From:	Tang Chen <tangchen@...fujitsu.com>
To:	Paolo Bonzini <pbonzini@...hat.com>, <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 v8 0/8] kvm, mem-hotplug: Do not pin ept identity pagetable
 and apic access page.

Hi Paolo,

I'd like to help to test the patches.
Would you please tell me what is the best way to test this patch-set ?

I think ept page is being used by regular guest.
Is adding "-cpu xxx,-x2apic option" able to make sure guest is using
apic page ?

Thanks.

On 09/24/2014 04:20 PM, Paolo Bonzini wrote:
> Il 24/09/2014 09:57, Tang Chen ha scritto:
>> 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.
>>
>> This patch-set is based on Linux 3.17.0-rc5.
>>
>> 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 v7->v8:
>> 1. Patch 1/9~3/9 were applied to kvm/queue by Paolo Bonzini <pbonzini@...hat.com>.
>>     Just resend them, no changes.
>> 2. Removed previous patch 4/9, which added unnecessary hook has_secondary_apic_access().
>> 3. Set kvm_x86_ops->set_apic_access_page_addr to NULL when hardware had no flexpriority
>>     functionality which actually exists only on x86.
>> 4. Moved declaration of kvm_arch_mmu_notifier_invalidate_page() to arch/*/include/asm/kvm_host.h.
>> 5. Removed useless set_apic_access_page_addr() hook for svm.
>>
>> Tang Chen (8):
>>    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's apic access page in vcpu_enter_guest().
>>    kvm: Rename make_all_cpus_request() to kvm_make_all_cpus_request() and
>>      make it non-static.
>>    kvm, mem-hotplug: Reload L1's apic access page on migration when L2 is
>>      running.
>>    kvm, mem-hotplug: Add arch specific mmu notifier to handle apic access
>>      migration.
>>    kvm, mem-hotplug: Unpin and remove kvm_arch->apic_access_page.
>>
>>   arch/arm/include/asm/kvm_host.h     |   5 ++
>>   arch/arm64/include/asm/kvm_host.h   |   5 ++
>>   arch/ia64/include/asm/kvm_host.h    |   7 ++
>>   arch/mips/include/asm/kvm_host.h    |   6 ++
>>   arch/powerpc/include/asm/kvm_host.h |   5 ++
>>   arch/s390/include/asm/kvm_host.h    |   8 +++
>>   arch/x86/include/asm/kvm_host.h     |   7 +-
>>   arch/x86/kvm/svm.c                  |   3 +-
>>   arch/x86/kvm/vmx.c                  | 130 ++++++++++++++++++++++++------------
>>   arch/x86/kvm/x86.c                  |  45 +++++++++++--
>>   include/linux/kvm_host.h            |   2 +
>>   virt/kvm/kvm_main.c                 |  13 ++--
>>   12 files changed, 180 insertions(+), 56 deletions(-)
>>
> Thanks for your persistence!  The patches look good, I'll test them and
> apply to kvm/queue.
>
> Paolo
> .
>

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