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x86/Hyper-V: Trigger crash enlightenment only once during system crash.

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commit 73f26e526f19afb3a06b76b970a76bcac2cafd05 upstream.

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: 7ed4325a44 ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tianyu Lan 2020-04-06 08:53:28 -07:00 committed by Greg Kroah-Hartman
parent 9f38f7b46d
commit 1ed38a9847
1 changed files with 14 additions and 2 deletions
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16
drivers/hv/vmbus_drv.c
View File

@ -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);
}
@ -68,7 +74,13 @@ 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;
hyperv_report_panic(regs, val);
/*
* 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;
}