* Re: discuss about pvpanic [not found] <2feff896-21fe-2bbe-6f68-9edfb476a110@bytedance.com> @ 2020-01-08 9:36 ` Paolo Bonzini 2020-01-08 9:58 ` Michal Privoznik 0 siblings, 1 reply; 4+ messages in thread From: Paolo Bonzini @ 2020-01-08 9:36 UTC (permalink / raw) To: zhenwei pi Cc: yelu, Greg KH, qemu-devel, linux-kernel, Michal Privoznik, libvir-list On 08/01/20 09:25, zhenwei pi wrote: > Hey, Paolo > > Currently, pvpapic only supports bit 0(PVPANIC_PANICKED). > We usually expect that guest writes ioport (typical 0x505) in panic_notifier_list callback > during handling panic, then we can handle pvpapic event PVPANIC_PANICKED in QEMU. > > On the other hand, guest wants to handle the crash by kdump-tools, and reboots without any > panic_notifier_list callback. So QEMU only knows that guest has rebooted (because guest > write 0xcf9 ioport for RCR request), but QEMU can't identify why guest resets. > > In production environment, we hit about 100+ guest reboot event everyday, sadly we > can't separate the abnormal reboot from normal operation. > > We want to add a new bit for pvpanic event(maybe PVPANIC_CRASHLOADED) to represent the guest has crashed, > and the panic is handled by the guest kernel. (here is the previous patch https://lkml.org/lkml/2019/12/14/265) > > What do you think about this solution? Or do you have any other suggestions? Hi Zhenwei, the kernel-side patch certainly makes sense. I assume that you want the event to propagate up from QEMU to Libvirt and so on? The QEMU patch would need to declare a new event (qapi/misc.json) and send it in handle_event (hw/misc/pvpanic.c). For Libvirt I'm not familiar, so I'm adding the respective list. Another possibility is to simply not write to pvpanic if kexec_crash_loaded() returns true; this would match what xen_panic_event does for example. The kexec kernel would then log the panic normally, without the need for MMIO at all. However, I have no problem with adding a new bit to the pvpanic I/O port so once you post the QEMU patch I will certainly ack the kernel side. Thanks, Paolo ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: discuss about pvpanic 2020-01-08 9:36 ` discuss about pvpanic Paolo Bonzini @ 2020-01-08 9:58 ` Michal Privoznik 2020-01-08 10:05 ` Paolo Bonzini 0 siblings, 1 reply; 4+ messages in thread From: Michal Privoznik @ 2020-01-08 9:58 UTC (permalink / raw) To: Paolo Bonzini, zhenwei pi Cc: yelu, Greg KH, qemu-devel, linux-kernel, libvir-list On 1/8/20 10:36 AM, Paolo Bonzini wrote: > On 08/01/20 09:25, zhenwei pi wrote: >> Hey, Paolo >> >> Currently, pvpapic only supports bit 0(PVPANIC_PANICKED). >> We usually expect that guest writes ioport (typical 0x505) in panic_notifier_list callback >> during handling panic, then we can handle pvpapic event PVPANIC_PANICKED in QEMU. >> >> On the other hand, guest wants to handle the crash by kdump-tools, and reboots without any >> panic_notifier_list callback. So QEMU only knows that guest has rebooted (because guest >> write 0xcf9 ioport for RCR request), but QEMU can't identify why guest resets. >> >> In production environment, we hit about 100+ guest reboot event everyday, sadly we >> can't separate the abnormal reboot from normal operation. >> >> We want to add a new bit for pvpanic event(maybe PVPANIC_CRASHLOADED) to represent the guest has crashed, >> and the panic is handled by the guest kernel. (here is the previous patch https://lkml.org/lkml/2019/12/14/265) >> >> What do you think about this solution? Or do you have any other suggestions? > > Hi Zhenwei, > > the kernel-side patch certainly makes sense. I assume that you want the > event to propagate up from QEMU to Libvirt and so on? The QEMU patch > would need to declare a new event (qapi/misc.json) and send it in > handle_event (hw/misc/pvpanic.c). For Libvirt I'm not familiar, so I'm > adding the respective list. Adding an event is fairly easy, if everything you want libvirt to do is report the event to upper layers. I volunteer to do it. Question is, how qemu is going to report this, whether some attributes to GUEST_PANICKED event or some new event. But more important is to merge the change into kernel. Michal ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: discuss about pvpanic 2020-01-08 9:58 ` Michal Privoznik @ 2020-01-08 10:05 ` Paolo Bonzini [not found] ` <d915c9e6-1ad7-4f8f-a66a-c418d43e977f@bytedance.com> 0 siblings, 1 reply; 4+ messages in thread From: Paolo Bonzini @ 2020-01-08 10:05 UTC (permalink / raw) To: Michal Privoznik, zhenwei pi Cc: yelu, Greg KH, qemu-devel, linux-kernel, libvir-list On 08/01/20 10:58, Michal Privoznik wrote: >> the kernel-side patch certainly makes sense. I assume that you want the >> event to propagate up from QEMU to Libvirt and so on? The QEMU patch >> would need to declare a new event (qapi/misc.json) and send it in >> handle_event (hw/misc/pvpanic.c). For Libvirt I'm not familiar, so I'm >> adding the respective list. > > Adding an event is fairly easy, if everything you want libvirt to do is > report the event to upper layers. I volunteer to do it. Question is, how > qemu is going to report this, whether some attributes to GUEST_PANICKED > event or some new event. I think it should be a new event, using GUEST_PANICKED could cause upper layers to react by shutting down or rebooting the guest. Thanks, Paolo ^ permalink raw reply [flat|nested] 4+ messages in thread
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* Re: [External] Re: discuss about pvpanic [not found] ` <d915c9e6-1ad7-4f8f-a66a-c418d43e977f@bytedance.com> @ 2020-01-08 12:14 ` Paolo Bonzini 0 siblings, 0 replies; 4+ messages in thread From: Paolo Bonzini @ 2020-01-08 12:14 UTC (permalink / raw) To: zhenwei pi, Michal Privoznik Cc: yelu, Greg KH, qemu-devel, linux-kernel, libvir-list On 08/01/20 11:33, zhenwei pi wrote: > In previous patch(https://lkml.org/lkml/2019/12/14/265), I defined a new bit (bit 1) > PVPANIC_CRASH_LOADED for guest crash loaded event. And suggested by KH Greg, I moved > the bit definition to an uapi header file. > Then QEMU could include the header file from linux header and handle the new event. Sure; QEMU has already got a mechanism to import files from Linux (scripts/update-linux-headers.sh). Paolo ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2020-01-08 12:14 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- [not found] <2feff896-21fe-2bbe-6f68-9edfb476a110@bytedance.com> 2020-01-08 9:36 ` discuss about pvpanic Paolo Bonzini 2020-01-08 9:58 ` Michal Privoznik 2020-01-08 10:05 ` Paolo Bonzini [not found] ` <d915c9e6-1ad7-4f8f-a66a-c418d43e977f@bytedance.com> 2020-01-08 12:14 ` [External] " Paolo Bonzini
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