[RFC PATCH 2/4] panic: run the pre kdump list before crash kexec

Call the new list unconditionally in vpanic, right before the
early crash kexec. The legacy list, crash_kexec_post_notifiers
and the cpu shutdown sequence are untouched. Also note in the
kernel parameters entry that the option has no effect on the
pre kdump list.

Signed-off-by: Bradley Morgan <[email protected]>
---
 Documentation/admin-guide/kernel-parameters.txt | 3 +++
 kernel/panic.c                                  | 7 +++++++
 2 files changed, 10 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index b5493a7f8f22..a77ecf3bd564 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1042,6 +1042,9 @@ Kernel parameters
 			or extra data dumped by panic_print. Note that some
 			configurations enable this option unconditionally,
 			like Hyper-V, PowerPC (fadump) and AMD SEV-SNP.
+			This option does not affect the pre kdump notifier
+			list (see include/linux/panic_notifier.h), which
+			always runs before the jump to the kdump kernel.
 
 	crashkernel=size[KMG][@offset[KMG]]
 			[KNL,EARLY] Using kexec, Linux can switch to a 'crash kernel'
diff --git a/kernel/panic.c b/kernel/panic.c
index 94ce7a94f118..f9ad0250da67 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -664,6 +664,13 @@ void vpanic(const char *fmt, va_list args)
 	 */
 	kgdb_panic(buf);
 
+	/*
+	 * Tell the hypervisor or firmware about the panic. This runs on
+	 * every panic, before a potential crash kexec, so the upcall is
+	 * not lost when a crash kernel is loaded.
+	 */
+	panic_pre_kdump_notify(buf);
+
 	/*
 	 * If we have crashed and we have a crash kernel loaded let it handle
 	 * everything else.
-- 
2.53.0