[3.19.y-ckt stable] Patch "Drivers: hv: vmbus: Add support for VMBus panic notifier handler" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    Drivers: hv: vmbus: Add support for VMBus panic notifier handler

to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue

This patch is scheduled to be released in version 3.19.8-ckt2.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 501f954032a22fef601f2d8514d2222dae4eff13 Mon Sep 17 00:00:00 2001
From: Nick Meier <nmeier at microsoft.com>
Date: Tue, 16 Jun 2015 16:22:12 -0400
Subject: Drivers: hv: vmbus: Add support for VMBus panic notifier handler

commit 96c1d0581d00f7abe033350edb021a9d947d8d81 upstream.

BugLink: http://bugs.launchpad.net/bugs/1463584

Hyper-V allows a guest to notify the Hyper-V host that a panic
condition occured.  This notification can include up to five 64
bit values.  These 64 bit values are written into crash MSRs.
Once the data has been written into the crash MSRs, the host is
then notified by writing into a Crash Control MSR.  On the Hyper-V
host, the panic notification data is captured in the Windows Event
log as a 18590 event.

Crash MSRs are defined in appendix H of the Hypervisor Top Level
Functional Specification.  At the time of this patch, v4.0 is the
current functional spec.  The URL for the v4.0 document is:

http://download.microsoft.com/download/A/B/4/AB43A34E-BDD0-4FA6-BDEF-79EEF16E880B/Hypervisor Top Level Functional Specification v4.0.docx

Signed-off-by: Nick Meier <nmeier at microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys at microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
(Backported from commit 96c1d0581d00f7abe033350edb021a9d947d8d81)
Signed-off-by: Joseph Salisbury <joseph.salisbury at canonical.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/hv/hyperv_vmbus.h | 11 +++++++++++
 drivers/hv/vmbus_drv.c    | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+)

diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index c386d8d..64318c0 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -49,6 +49,17 @@ enum hv_cpuid_function {
 	HVCPUID_IMPLEMENTATION_LIMITS		= 0x40000005,
 };

+#define  HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE   0x400
+
+#define HV_X64_MSR_CRASH_P0   0x40000100
+#define HV_X64_MSR_CRASH_P1   0x40000101
+#define HV_X64_MSR_CRASH_P2   0x40000102
+#define HV_X64_MSR_CRASH_P3   0x40000103
+#define HV_X64_MSR_CRASH_P4   0x40000104
+#define HV_X64_MSR_CRASH_CTL  0x40000105
+
+#define HV_CRASH_CTL_CRASH_NOTIFY 0x8000000000000000
+
 /* Define version of the synthetic interrupt controller. */
 #define HV_SYNIC_VERSION		(1)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 4d6b269..3d2d710 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -35,6 +35,8 @@
 #include <asm/hyperv.h>
 #include <asm/hypervisor.h>
 #include <asm/mshyperv.h>
+#include <linux/notifier.h>
+#include <linux/ptrace.h>
 #include "hyperv_vmbus.h"

 static struct acpi_device  *hv_acpi_dev;
@@ -43,6 +45,31 @@ static struct tasklet_struct msg_dpc;
 static struct completion probe_event;
 static int irq;

+
+int hyperv_panic_event(struct notifier_block *nb,
+			unsigned long event, void *ptr)
+{
+	struct pt_regs *regs;
+
+	regs = current_pt_regs();
+
+	wrmsrl(HV_X64_MSR_CRASH_P0, regs->ip);
+	wrmsrl(HV_X64_MSR_CRASH_P1, regs->ax);
+	wrmsrl(HV_X64_MSR_CRASH_P2, regs->bx);
+	wrmsrl(HV_X64_MSR_CRASH_P3, regs->cx);
+	wrmsrl(HV_X64_MSR_CRASH_P4, regs->dx);
+
+	/*
+	 * Let Hyper-V know there is crash data available
+	 */
+	wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block hyperv_panic_block = {
+	.notifier_call = hyperv_panic_event,
+};
+
 struct resource hyperv_mmio = {
 	.name  = "hyperv mmio",
 	.flags = IORESOURCE_MEM,
@@ -711,6 +738,14 @@ static int vmbus_bus_init(int irq)
 	if (ret)
 		goto err_alloc;

+	/*
+	 * Only register if the crash MSRs are available
+	 */
+	if (ms_hyperv.features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {
+		atomic_notifier_chain_register(&panic_notifier_list,
+					       &hyperv_panic_block);
+	}
+
 	vmbus_request_offers();

 	return 0;
--
1.9.1