x86/Hyper-V: Trigger crash enlightenment only once during system crash. (73f26e52) · Commits · 戴 / test

When a guest VM panics, Hyper-V should be notified only once via the crash synthetic MSRs. Current Linux code might write these crash MSRs twice during a system panic: 1) hyperv_panic/die_event() calling hyperv_report_panic() 2) hv_kmsg_dump() calling hyperv_report_panic_msg() Fix this by not calling hyperv_report_panic() if a kmsg dump has been successfully registered. The notification will happen later via hyperv_report_panic_msg(). Fixes: ("Drivers: hv: vmbus: Make panic reporting to be more useful") Reviewed-by:

Michael Kelley <mikelley@microsoft.com> Signed-off-by:

Tianyu Lan <Tianyu.Lan@microsoft.com> Link: https://lore.kernel.org/r/20200406155331.2105-4-Tianyu.Lan@microsoft.com Signed-off-by:

Wei Liu <wei.liu@kernel.org>

drivers/hv/vmbus_drv.c

+14 −2

Original line number	Diff line number	Diff line
		@@ -55,7 +55,13 @@ static int hyperv_panic_event(struct notifier_block *nb, unsigned long val,

		vmbus_initiate_unload(true);

		if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {
		/*
		* Hyper-V should be notified only once about a panic. If we will be
		* doing hyperv_report_panic_msg() later with kmsg data, don't do
		* the notification here.
		*/
		if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE
		&& !hv_panic_page) {
		regs = current_pt_regs();
		hyperv_report_panic(regs, val);
		}
		@@ -68,6 +74,12 @@ static int hyperv_die_event(struct notifier_block *nb, unsigned long val,
		struct die_args die = (struct die_args )args;
		struct pt_regs *regs = die->regs;

		/*
		* Hyper-V should be notified only once about a panic. If we will be
		* doing hyperv_report_panic_msg() later with kmsg data, don't do
		* the notification here.
		*/
		if (!hv_panic_page)
		hyperv_report_panic(regs, val);
		return NOTIFY_DONE;
		}

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