[RFC PATCH 4/4] x86: Invoke pre_restart notifiers

From: Mathieu Desnoyers
Date: Tue Jun 18 2024 - 11:53:17 EST


Invoke the pre_restart notifiers after shutdown, before machine restart.
This allows preserving pmem memory across warm reboots.

Invoke the pre_restart notifiers on emergency_machine_restart to cover
the panic() scenario.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Vishal Verma <vishal.l.verma@xxxxxxxxx>
Cc: Dave Jiang <dave.jiang@xxxxxxxxx>
Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: nvdimm@xxxxxxxxxxxxxxx
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
---
arch/x86/kernel/reboot.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index f3130f762784..222619fa63c6 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -631,8 +631,10 @@ static void native_machine_emergency_restart(void)
int orig_reboot_type = reboot_type;
unsigned short mode;

- if (reboot_emergency)
+ if (reboot_emergency) {
+ do_kernel_pre_restart(NULL);
emergency_reboot_disable_virtualization();
+ }

tboot_shutdown(TB_SHUTDOWN_REBOOT);

@@ -760,12 +762,13 @@ static void __machine_emergency_restart(int emergency)
machine_ops.emergency_restart();
}

-static void native_machine_restart(char *__unused)
+static void native_machine_restart(char *cmd)
{
pr_notice("machine restart\n");

if (!reboot_force)
machine_shutdown();
+ do_kernel_pre_restart(cmd);
__machine_emergency_restart(0);
}

--
2.39.2