@@ -25,7 +25,6 @@
#include <linux/sched/task_stack.h>
#include <linux/delay.h>
-#include <linux/notifier.h>
#include <linux/panic_notifier.h>
#include <linux/ptrace.h>
#include <linux/screen_info.h>
@@ -69,53 +68,74 @@ 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,
+/*
+ * The panic notifier below is responsible solely for unloading the
+ * vmbus connection, which is necessary in a panic event.
+ *
+ * Notice an intrincate relation of this notifier with Hyper-V
+ * framebuffer panic notifier exists - we need vmbus connection alive
+ * there in order to succeed, so we need to order both with each other
+ * [see hvfb_on_panic()] - this is done using notifiers' priorities.
+ */
+static int hv_panic_vmbus_unload(struct notifier_block *nb, unsigned long val,
void *args)
+{
+ vmbus_initiate_unload(true);
+ return NOTIFY_DONE;
+}
+static struct notifier_block hyperv_panic_vmbus_unload_block = {
+ .notifier_call = hv_panic_vmbus_unload,
+ .priority = INT_MIN + 1, /* almost the latest one to execute */
+};
+
+static int hv_die_panic_notify_crash(struct notifier_block *self,
+ unsigned long val, void *args);
+
+static struct notifier_block hyperv_die_report_block = {
+ .notifier_call = hv_die_panic_notify_crash,
+};
+static struct notifier_block hyperv_panic_report_block = {
+ .notifier_call = hv_die_panic_notify_crash,
+};
+
+/*
+ * The following callback works both as die and panic notifier; its
+ * goal is to provide panic information to the hypervisor unless the
+ * kmsg dumper is used [see hv_kmsg_dump()], which provides more
+ * information but isn't always available.
+ *
+ * Notice that both the panic/die report notifiers are registered only
+ * if we have the capability HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE set.
+ */
+static int hv_die_panic_notify_crash(struct notifier_block *self,
+ unsigned long val, void *args)
{
struct pt_regs *regs;
+ bool is_die;
- vmbus_initiate_unload(true);
-
- /*
- * Hyper-V should be notified only once about a panic. If we will be
- * doing hv_kmsg_dump() with kmsg data later, don't do the notification
- * here.
- */
- if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE
- && hyperv_report_reg()) {
+ /* Don't notify Hyper-V unless we have a die oops event or panic. */
+ if (self == &hyperv_panic_report_block) {
+ is_die = false;
regs = current_pt_regs();
- hyperv_report_panic(regs, val, false);
+ } else { /* die event */
+ if (val != DIE_OOPS)
+ return NOTIFY_DONE;
+
+ is_die = true;
+ regs = ((struct die_args *)args)->regs;
}
- return NOTIFY_DONE;
-}
-
-static int hyperv_die_event(struct notifier_block *nb, unsigned long val,
- void *args)
-{
- struct die_args *die = args;
- struct pt_regs *regs = die->regs;
-
- /* Don't notify Hyper-V if the die event is other than oops */
- if (val != DIE_OOPS)
- return NOTIFY_DONE;
/*
- * Hyper-V should be notified only once about a panic. If we will be
- * doing hv_kmsg_dump() with kmsg data later, don't do the notification
- * here.
+ * Hyper-V should be notified only once about a panic/die. If we will
+ * be calling hv_kmsg_dump() later with kmsg data, don't do the
+ * notification here.
*/
if (hyperv_report_reg())
- hyperv_report_panic(regs, val, true);
+ hyperv_report_panic(regs, val, is_die);
+
return NOTIFY_DONE;
}
-static struct notifier_block hyperv_die_block = {
- .notifier_call = hyperv_die_event,
-};
-static struct notifier_block hyperv_panic_block = {
- .notifier_call = hyperv_panic_event,
-};
-
static const char *fb_mmio_name = "fb_range";
static struct resource *fb_mmio;
static struct resource *hyperv_mmio;
@@ -1534,16 +1554,17 @@ static int vmbus_bus_init(void)
if (hyperv_crash_ctl & HV_CRASH_CTL_CRASH_NOTIFY_MSG)
hv_kmsg_dump_register();
- register_die_notifier(&hyperv_die_block);
+ register_die_notifier(&hyperv_die_report_block);
+ atomic_notifier_chain_register(&panic_notifier_list,
+ &hyperv_panic_report_block);
}
/*
- * Always register the panic notifier because we need to unload
- * the VMbus channel connection to prevent any VMbus
- * activity after the VM panics.
+ * Always register the vmbus unload panic notifier because we
+ * need to shut the VMbus channel connection on panic.
*/
atomic_notifier_chain_register(&panic_notifier_list,
- &hyperv_panic_block);
+ &hyperv_panic_vmbus_unload_block);
vmbus_request_offers();
@@ -2765,15 +2786,17 @@ static void __exit vmbus_exit(void)
if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {
kmsg_dump_unregister(&hv_kmsg_dumper);
- unregister_die_notifier(&hyperv_die_block);
+ unregister_die_notifier(&hyperv_die_report_block);
+ atomic_notifier_chain_unregister(&panic_notifier_list,
+ &hyperv_panic_report_block);
}
/*
- * The panic notifier is always registered, hence we should
+ * The vmbus panic notifier is always registered, hence we should
* also unconditionally unregister it here as well.
*/
atomic_notifier_chain_unregister(&panic_notifier_list,
- &hyperv_panic_block);
+ &hyperv_panic_vmbus_unload_block);
free_page((unsigned long)hv_panic_page);
unregister_sysctl_table(hv_ctl_table_hdr);
@@ -1216,7 +1216,15 @@ static int hvfb_probe(struct hv_device *hdev,
par->fb_ready = true;
par->synchronous_fb = false;
+
+ /*
+ * We need to be sure this panic notifier runs _before_ the
+ * vmbus disconnect, so order it by priority. It must execute
+ * before the function hv_panic_vmbus_unload() [drivers/hv/vmbus_drv.c],
+ * which is almost at the end of list, with priority = INT_MIN + 1.
+ */
par->hvfb_panic_nb.notifier_call = hvfb_on_panic;
+ par->hvfb_panic_nb.priority = INT_MIN + 10,
atomic_notifier_chain_register(&panic_notifier_list,
&par->hvfb_panic_nb);