On 06.05.22 15:38, zhenwei pi wrote: > > > On 5/6/22 16:59, Naoya Horiguchi wrote: >> On Fri, Apr 29, 2022 at 10:22:05PM +0800, zhenwei pi wrote: >>> In the memory failure procedure, hwpoison_filter has higher priority, >>> if memory_filter() filters the error event, there is no need to do >>> the further work. >> >> Could you clarify what problem you are trying to solve (what does >> "optimize" mean in this context or what is the benefit)? >> > > OK. The background of this work: > As well known, the memory failure mechanism handles memory corrupted > event, and try to send SIGBUS to the user process which uses this > corrupted page. > > For the virtualization case, QEMU catches SIGBUS and tries to inject MCE > into the guest, and the guest handles memory failure again. Thus the > guest gets the minimal effect from hardware memory corruption. > > The further step I'm working on: > 1, try to modify code to decrease poisoned pages in a single place > (mm/memofy-failure.c: simplify num_poisoned_pages_dec in this series). > > 2, try to use page_handle_poison() to handle SetPageHWPoison() and > num_poisoned_pages_inc() together. It would be best to call > num_poisoned_pages_inc() in a single place too. I'm not sure if this is > possible or not, please correct me if I misunderstand. > > 3, introduce memory failure notifier list in memory-failure.c: notify > the corrupted PFN to someone who registers this list. > If I can complete [1] and [2] part, [3] will be quite easy(just call > notifier list after increasing poisoned page). > > 4, introduce memory recover VQ for memory balloon device, and registers > memory failure notifier list. During the guest kernel handles memory > failure, balloon device gets notified by memory failure notifier list, > and tells the host to recover the corrupted PFN(GPA) by the new VQ. Most probably you might want to do that asynchronously, and once the callback succeeds, un-poison the page. > > 5, host side remaps the corrupted page(HVA), and tells the guest side to > unpoison the PFN(GPA). Then the guest fixes the corrupted page(GPA) > dynamically. I think QEMU already does that during reboots. Now it would be triggered by the guest for individual pages. > > Because [4] and [5] are related to balloon device, also CC Michael, > David and Jason. Doesn't sound too crazy for me, although it's a shame that we always have to use virtio-balloon for such fairly balloon-unrelated things. -- Thanks, David / dhildenb _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
