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Message-ID: <d41bf9f8-9ea2-e4be-7e96-d69d2e4ec5f2@bytedance.com>
Date:   Fri, 27 May 2022 11:47:04 +0800
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Subject: Re: [PATCH 0/3] recover hardware corrupted page by virtio balloon
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To:     akpm@linux-foundation.org, naoya.horiguchi@nec.com
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org, mst@redhat.com,
        david@redhat.com, jasowang@redhat.com,
        virtualization@lists.linux-foundation.org, pbonzini@redhat.com,
        peterx@redhat.com, qemu-devel@nongnu.org
References: <20220520070648.1794132-1-pizhenwei@bytedance.com>
From:   zhenwei pi <pizhenwei@bytedance.com>
In-Reply-To: <20220520070648.1794132-1-pizhenwei@bytedance.com>
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Hi, Andrew & Naoya

I would appreciate it if you could give me any hint about the changes of 
memory/memory-failure!

On 5/20/22 15:06, zhenwei pi wrote:
> Hi,
> 
> I'm trying to recover hardware corrupted page by virtio balloon, the
> workflow of this feature like this:
> 
> Guest              5.MF -> 6.RVQ FE    10.Unpoison page
>                      /           \            /
> -------------------+-------------+----------+-----------
>                     |             |          |
>                  4.MCE        7.RVQ BE   9.RVQ Event
>   QEMU             /               \       /
>               3.SIGBUS              8.Remap
>                  /
> ----------------+------------------------------------
>                  |
>              +--2.MF
>   Host       /
>         1.HW error
> 
> 1, HardWare page error occurs randomly.
> 2, host side handles corrupted page by Memory Failure mechanism, sends
>     SIGBUS to the user process if early-kill is enabled.
> 3, QEMU handles SIGBUS, if the address belongs to guest RAM, then:
> 4, QEMU tries to inject MCE into guest.
> 5, guest handles memory failure again.
> 
> 1-5 is already supported for a long time, the next steps are supported
> in this patch(also related driver patch):
> 
> 6, guest balloon driver gets noticed of the corrupted PFN, and sends
>     request to host side by Recover VQ FrontEnd.
> 7, QEMU handles request from Recover VQ BackEnd, then:
> 8, QEMU remaps the corrupted HVA fo fix the memory failure, then:
> 9, QEMU acks the guest side the result by Recover VQ.
> 10, guest unpoisons the page if the corrupted page gets recoverd
>      successfully.
> 
> Test:
> This patch set can be tested with QEMU(also in developing):
> https://github.com/pizhenwei/qemu/tree/balloon-recover
> 
> Emulate MCE by QEMU(guest RAM normal page only, hugepage is not supported):
> virsh qemu-monitor-command vm --hmp mce 0 9 0xbd000000000000c0 0xd 0x61646678 0x8c
> 
> The guest works fine(on Intel Platinum 8260):
>   mce: [Hardware Error]: Machine check events logged
>   Memory failure: 0x61646: recovery action for dirty LRU page: Recovered
>   virtio_balloon virtio5: recovered pfn 0x61646
>   Unpoison: Unpoisoned page 0x61646 by virtio-balloon
>   MCE: Killing stress:24502 due to hardware memory corruption fault at 7f5be2e5a010
> 
> And the 'HardwareCorrupted' in /proc/meminfo also shows 0 kB.
> 
> About the protocol of virtio balloon recover VQ, it's undefined and in
> developing currently:
> - 'struct virtio_balloon_recover' defines the structure which is used to
>    exchange message between guest and host.
> - '__le32 corrupted_pages' in struct virtio_balloon_config is used in the next
>    step:
>    1, a VM uses RAM of 2M huge page, once a MCE occurs, the 2M becomes
>       unaccessible. Reporting 512 * 4K 'corrupted_pages' to the guest, the guest
>       has a chance to isolate the 512 pages ahead of time.
> 
>    2, after migrating to another host, the corrupted pages are actually recovered,
>       once the guest gets the 'corrupted_pages' with 0, then the guest could
>       unpoison all the poisoned pages which are recorded in the balloon driver.
> 
> zhenwei pi (3):
>    memory-failure: Introduce memory failure notifier
>    mm/memory-failure.c: support reset PTE during unpoison
>    virtio_balloon: Introduce memory recover
> 
>   drivers/virtio/virtio_balloon.c     | 243 ++++++++++++++++++++++++++++
>   include/linux/mm.h                  |   4 +-
>   include/uapi/linux/virtio_balloon.h |  16 ++
>   mm/hwpoison-inject.c                |   2 +-
>   mm/memory-failure.c                 |  59 ++++++-
>   5 files changed, 315 insertions(+), 9 deletions(-)
> 

-- 
zhenwei pi