The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 040026df7088c56ccbad28f7042308f67bde63df Mon Sep 17 00:00:00 2001
From: Tianyu Lan Tianyu.Lan@microsoft.com Date: Mon, 6 Apr 2020 08:53:30 -0700 Subject: [PATCH] x86/Hyper-V: Report crash register data when sysctl_record_panic_msg is not set
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().
Fixes: 81b18bce48af ("Drivers: HV: Send one page worth of kmsg dump over Hyper-V during panic") Reviewed-by: Michael Kelley mikelley@microsoft.com Signed-off-by: Tianyu Lan Tianyu.Lan@microsoft.com Link: https://lore.kernel.org/r/20200406155331.2105-6-Tianyu.Lan@microsoft.com Signed-off-by: Wei Liu wei.liu@kernel.org
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c index 333dad39b1c1..172ceae69abb 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) { @@ -61,7 +73,7 @@ static int hyperv_panic_event(struct notifier_block *nb, unsigned long val, * the notification here. */ 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); } @@ -79,7 +91,7 @@ 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 (!hv_panic_page) + if (hyperv_report_reg()) hyperv_report_panic(regs, val); return NOTIFY_DONE; } @@ -1267,13 +1279,6 @@ 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.