From: Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx> Sent: Monday, March 23, 2020 6:09 AM
>
> When sysctl_record_panic_msg is not set, kmsg will
> not be reported to Hyper-V. Crash register data should
> be reported via hyperv_report_panic() in such case.
Tweaking the wording:
When sysctl_record_panic_msg is not set, the panic will
not be reported to Hyper-V via hyperv_report_panic_msg().
So the crash should be reported via hyperv_report_panic().
>
> Signed-off-by: Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx>
> ---
> drivers/hv/vmbus_drv.c | 23 ++++++++++++++---------
> 1 file changed, 14 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index d73fa8aa00a3..00447175c040 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -48,6 +48,18 @@ static int hyperv_cpuhp_online;
>
> static void *hv_panic_page;
>
> +/*
> + * Boolean to control whether to report panic messages over Hyper-V.
> + *
> + * It can be set via /proc/sys/kernel/hyperv/record_panic_msg
> + */
> +static int sysctl_record_panic_msg = 1;
> +
> +static int hyperv_report_reg(void)
> +{
> + return !sysctl_record_panic_msg || !hv_panic_page;
> +}
> +
> static int hyperv_panic_event(struct notifier_block *nb, unsigned long val,
> void *args)
> {
> @@ -60,7 +72,7 @@ static int hyperv_panic_event(struct notifier_block *nb, unsigned long
> val,
> * message is available, just report kmsg to crash buffer.
> */
> if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE
> - && !hv_panic_page) {
> + && hyperv_report_reg()) {
> regs = current_pt_regs();
> hyperv_report_panic(regs, val);
> }
> @@ -77,7 +89,7 @@ static int hyperv_die_event(struct notifier_block *nb, unsigned long
> val,
> * Crash notify only can be triggered once. If crash notify
> * message is available, just report kmsg to crash buffer.
> */
> - if (!hv_panic_page)
> + if (hyperv_report_reg())
> hyperv_report_panic(regs, val);
> return NOTIFY_DONE;
> }
> @@ -1265,13 +1277,6 @@ static void vmbus_isr(void)
> add_interrupt_randomness(HYPERVISOR_CALLBACK_VECTOR, 0);
> }
>
> -/*
> - * Boolean to control whether to report panic messages over Hyper-V.
> - *
> - * It can be set via /proc/sys/kernel/hyperv/record_panic_msg
> - */
> -static int sysctl_record_panic_msg = 1;
> -
> /*
> * Callback from kmsg_dump. Grab as much as possible from the end of the kmsg
> * buffer and call into Hyper-V to transfer the data.
> --
> 2.14.5
