Messages in this thread | | | Date | Thu, 12 Dec 2019 14:35:39 +0100 | From | Greg KH <> | Subject | Re: [External] Re: [PATCH] misc: pvpanic: add crash loaded event |
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On Thu, Dec 12, 2019 at 09:26:22PM +0800, zhenwei pi wrote: > On 12/12/19 9:01 PM, Greg KH wrote: > > > On Thu, Dec 12, 2019 at 08:32:26PM +0800, zhenwei pi wrote: > > > Some users prefer kdump tools to generate guest kernel dumpfile, > > > at the same time, need a out-of-band kernel panic event. > > > > > > Currently if booting guest kernel with 'crash_kexec_post_notifiers', > > > QEMU will recieve PVPANIC_PANICKED event and stop VM. If booting > > > guest kernel without 'crash_kexec_post_notifiers', guest will not > > > call notifier chain. > > > > > > Add PVPANIC_CRASH_LOADED bit for pvpanic event, it means that guest > > > actually hit a kernel panic, but kernel wants to handle by itself. > > > > > > Signed-off-by: zhenwei pi <pizhenwei@bytedance.com> > > > --- > > > drivers/misc/pvpanic.c | 10 +++++++++- > > > 1 file changed, 9 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/misc/pvpanic.c b/drivers/misc/pvpanic.c > > > index 95ff7c5a1dfb..a8cc96c90550 100644 > > > --- a/drivers/misc/pvpanic.c > > > +++ b/drivers/misc/pvpanic.c > > > @@ -10,6 +10,7 @@ > > > #include <linux/acpi.h> > > > #include <linux/kernel.h> > > > +#include <linux/kexec.h> > > > #include <linux/module.h> > > > #include <linux/of.h> > > > #include <linux/of_address.h> > > > @@ -19,6 +20,7 @@ > > > static void __iomem *base; > > > #define PVPANIC_PANICKED (1 << 0) > > > +#define PVPANIC_CRASH_LOADED (1 << 1) > > BIT(1)? > > zhenwei: yes, define PVPANIC_CRASH_LOADED as BIT(1)? > > > > > > MODULE_AUTHOR("Hu Tao <hutao@cn.fujitsu.com>"); > > > MODULE_DESCRIPTION("pvpanic device driver"); > > > @@ -34,7 +36,13 @@ static int > > > pvpanic_panic_notify(struct notifier_block *nb, unsigned long code, > > > void *unused) > > > { > > > - pvpanic_send_event(PVPANIC_PANICKED); > > > + unsigned int event = PVPANIC_PANICKED; > > > + > > > + if (kexec_crash_loaded()) > > > + event = PVPANIC_CRASH_LOADED; > > > + > > > + pvpanic_send_event(event); > > Who gets this event to know that the above new bit is set or not? > > Hypervisor will catch this event. A typical case maybe like this: guest os triggers > pvpanic PVPANIC_CRASH_LOADED event, QEMU gets this event by handling vm-exit reason, > then QEMU posts event to libvirt. Monotor agent gets domain lifecycle event from > libvirt. Bingo, we can know that the guest has crashed but it handle error by > kexec crash loaded image.
But as you have burried this user api value in a random .c file, how does anything outside of the kernel know what the value really is for?
Shouldn't the #define be in a uapi file?
thanks,
greg k-h-
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