linux-kernel - [PATCH 5.4 022/118] x86/Hyper-V: Report crash register data when sysctl_record_panic

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Date:   Wed, 22 Apr 2020 11:56:23 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Michael Kelley <mikelley@...rosoft.com>,
        Tianyu Lan <Tianyu.Lan@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>
Subject: [PATCH 5.4 022/118] x86/Hyper-V: Report crash register data when sysctl_record_panic_msg is not set

From: Tianyu Lan <Tianyu.Lan@...rosoft.com>

commit 040026df7088c56ccbad28f7042308f67bde63df upstream.

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@...rosoft.com>
Signed-off-by: Tianyu Lan <Tianyu.Lan@...rosoft.com>
Link: https://lore.kernel.org/r/20200406155331.2105-6-Tianyu.Lan@microsoft.com
Signed-off-by: Wei Liu <wei.liu@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/hv/vmbus_drv.c |   23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

--- 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 not
 	 * 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 notif
 	 * 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;
 }
@@ -1262,13 +1274,6 @@ static void vmbus_isr(void)
 }
 
 /*
- * 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.
  */