From: Tianyu Lan <Tianyu.Lan@microsoft.com>
Date: Mon, 6 Apr 2020 08:53:31 -0700
Patch-mainline: v5.7-rc2
Subject: x86/Hyper-V: Report crash data in die() when panic_on_oops is set
Git-commit: f3a99e761efa616028b255b4de58e9b5b87c5545
References: bsc#1170617, bsc#1170618

When oops happens with panic_on_oops unset, the oops
thread is killed by die() and system continues to run.
In such case, guest should not report crash register
data to host since system still runs. Check panic_on_oops
and return directly in hyperv_report_panic() when the function
is called in the die() and panic_on_oops is unset. Fix it.

Fixes: 7ed4325a44ea ("Drivers: hv: vmbus: Make panic reporting to be more useful")
Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20200406155331.2105-7-Tianyu.Lan@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Acked-by: Olaf Hering <ohering@suse.de>
---
 arch/x86/hyperv/hv_init.c      | 6 +++++-
 drivers/hv/vmbus_drv.c         | 5 +++--
 arch/x86/include/asm/mshyperv.h | 2 +-
 3 files changed, 9 insertions(+), 4 deletions(-)

--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -29,6 +29,7 @@
 #include <linux/mm.h>
 #include <linux/hyperv.h>
 #include <linux/slab.h>
+#include <linux/kernel.h>
 #include <linux/cpuhotplug.h>
 #include <clocksource/hyperv_timer.h>
 
@@ -432,6 +433,11 @@ void hyperv_report_panic(struct pt_regs
 {
 	static bool panic_reported;
 	u64 guest_id;
+	bool in_die = !!(err & (1 << 10));
+	err = err & ~(1 << 10);
+
+	if (in_die && !panic_on_oops)
+		return;
 
 	/*
 	 * We prefer to report panic on 'die' chain as we have proper
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -43,6 +43,7 @@
 #include <linux/kdebug.h>
 #include <linux/efi.h>
 #include <linux/random.h>
+#include <linux/kernel.h>
 #include <clocksource/hyperv_timer.h>
 #include "hyperv_vmbus.h"
 
@@ -85,7 +86,7 @@ static int hyperv_panic_event(struct not
 	if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE
 	    && hyperv_report_reg()) {
 		regs = current_pt_regs();
-		hyperv_report_panic(regs, val);
+		hyperv_report_panic(regs, val | (false << 10));
 	}
 	return NOTIFY_DONE;
 }
@@ -102,7 +103,7 @@ static int hyperv_die_event(struct notif
 	 * the notification here.
 	 */
 	if (hyperv_report_reg())
-		hyperv_report_panic(regs, val);
+		hyperv_report_panic(regs, val | (true << 10));
 	return NOTIFY_DONE;
 }