On 20.05.22 09:06, 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. > Hi, I'm still on vacation this week, I'll try to have a look when I'm back (and flushed out my overflowing inbox :D). -- Thanks, David / dhildenb
