linux-kernel - [PATCH V2 5/6] x86/Hyper-V: Report crash register data when sysctl_record_panic

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Message-Id: <20200323130924.2968-6-Tianyu.Lan@microsoft.com>
Date:   Mon, 23 Mar 2020 06:09:23 -0700
From:   ltykernel@...il.com
To:     kys@...rosoft.com, haiyangz@...rosoft.com, sthemmin@...rosoft.com,
        liuwe@...rosoft.com, michael.h.kelley@...rosoft.com
Cc:     Tianyu Lan <Tianyu.Lan@...rosoft.com>,
        linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org,
        vkuznets@...hat.com
Subject: [PATCH V2 5/6] x86/Hyper-V: Report crash register data when sysctl_record_panic_msg is not set

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

When sysctl_record_panic_msg is not set, kmsg will
not be reported to Hyper-V. Crash register data should
be reported via hyperv_report_panic() in such case.

Signed-off-by: Tianyu Lan <Tianyu.Lan@...rosoft.com>
---
 drivers/hv/vmbus_drv.c | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index d73fa8aa00a3..00447175c040 100644
--- 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)
 {
@@ -60,7 +72,7 @@ static int hyperv_panic_event(struct notifier_block *nb, unsigned long val,
 	 * message is available, just report kmsg to crash buffer.
 	 */
 	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);
 	}
@@ -77,7 +89,7 @@ static int hyperv_die_event(struct notifier_block *nb, unsigned long val,
 	 * Crash notify only can be triggered once. If crash notify
 	 * message is available, just report kmsg to crash buffer.
 	 */
-	if (!hv_panic_page)
+	if (hyperv_report_reg())
 		hyperv_report_panic(regs, val);
 	return NOTIFY_DONE;
 }
@@ -1265,13 +1277,6 @@ static void vmbus_isr(void)
 	add_interrupt_randomness(HYPERVISOR_CALLBACK_VECTOR, 0);
 }
 
-/*
- * 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.
-- 
2.14.5