RE: [PATCH V4 6/6] x86/Hyper-V: Report crash data in die() when panic_on_oops is set

Michael Kelley
2020-03-31T13:51:56Z

From: Tianyu Lan <Tianyu.Lan@microsoft.com> Sent: Tuesday, March 31, 2020 12:39 AM
>
> When oops happens with panic_on_oops unset, the oops
> thread is killed by die() and system continues to run.
> In such case, guest should not report crash register
> data to host since system still runs. Fix it.
>
> Reviewed-by: Michael Kelley <mikelley@microsoft.com>
> Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
> ---
> Change since v3:
> Fix compile error
> ---
> drivers/hv/vmbus_drv.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index 172ceae69abb..4bc02aea2098 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -31,6 +31,7 @@
> #include <linux/kdebug.h>
> #include <linux/efi.h>
> #include <linux/random.h>
> +#include <linux/kernel.h>

Unfortunately, adding the #include doesn't solve the problem. The error occurs when
CONFIG_HYPERV=m, because panic_on_oops is not exported. I haven't thought it
through, but hopefully there's a solution where panic_on_oops can be tested in
hyperv_report_panic() or some other Hyper-V specific function that's never in a
module, so that we don't need to export panic_on_oops.

Michael

> #include <linux/syscore_ops.h>
> #include <clocksource/hyperv_timer.h>
> #include "hyperv_vmbus.h"
> @@ -91,7 +92,7 @@ static int hyperv_die_event(struct notifier_block *nb, unsigned long
> val,
> * doing hyperv_report_panic_msg() later with kmsg data, don't do
> * the notification here.
> */
> - if (hyperv_report_reg())
> + if (hyperv_report_reg() && panic_on_oops)
> hyperv_report_panic(regs, val);
> return NOTIFY_DONE;
> }
> --
> 2.14.5