This is a note to let you know that I've just added the patch titled
x86/Hyper-V: Trigger crash enlightenment only once during system crash.
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-hyper-v-trigger-crash-enlightenment-only-once-during-system-crash.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 73f26e526f19afb3a06b76b970a76bcac2cafd05 Mon Sep 17 00:00:00 2001
From: Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx>
Date: Mon, 6 Apr 2020 08:53:28 -0700
Subject: x86/Hyper-V: Trigger crash enlightenment only once during system crash.
From: Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx>
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: 7ed4325a44ea ("Drivers: hv: vmbus: Make panic reporting to be more useful")
Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
Signed-off-by: Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20200406155331.2105-4-Tianyu.Lan@xxxxxxxxxxxxx
Signed-off-by: Wei Liu <wei.liu@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/hv/vmbus_drv.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -55,7 +55,13 @@ static int hyperv_panic_event(struct not
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 notif
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;
}
Patches currently in stable-queue which might be from Tianyu.Lan@xxxxxxxxxxxxx are
queue-5.4/x86-hyper-v-unload-vmbus-channel-in-hv-panic-callback.patch
queue-5.4/x86-hyper-v-trigger-crash-enlightenment-only-once-during-system-crash.patch
queue-5.4/x86-hyper-v-report-crash-register-data-or-kmsg-before-running-crash-kernel.patch
queue-5.4/x86-hyper-v-report-crash-register-data-when-sysctl_record_panic_msg-is-not-set.patch
queue-5.4/x86-hyper-v-report-crash-data-in-die-when-panic_on_oops-is-set.patch
