BACKPORT: ACPI / APEI: Don't wait to serialise with oops messages whe…

…n panic()ing

oops_begin() exists to group printk() messages with the oops message
printed by die(). To reach this caller we know that platform firmware
took this error first, then notified the OS via NMI with a 'panic'
severity.

Don't wait for another CPU to release the die-lock before panic()ing,
our only goal is to print this fatal error and panic().

This code is always called in_nmi(), and since commit 42a0bb3f7138
("printk/nmi: generic solution for safe printk in NMI"), it has been
safe to call printk() from this context. Messages are batched in a
per-cpu buffer and printed via irq-work, or a call back from panic().

This patch is needed because Quicksilver firmware-first error handling
uses the SDEI notification type for communication between trusted
firmware and the OS. This adds needed NMI and SDEI functionality so
that the SDEI path in the kernel through APEI acts as an NMI and is
properly wired up to the APEI interfaces.

Backported from: torvalds/linux@78b0b69

Link: https://patchwork.kernel.org/patch/10313555/
Acked-by: Borislav Petkov <[email protected]>
Signed-off-by: James Morse <[email protected]>
Signed-off-by: Tyler Baicar <[email protected]>

drivers/acpi/apei/ghes.c

@@ -33,7 +33,6 @@
 #include <linux/interrupt.h>
 #include <linux/timer.h>
 #include <linux/cper.h>
-#include <linux/kdebug.h>
 #include <linux/platform_device.h>
 #include <linux/mutex.h>
 #include <linux/ratelimit.h>
@@ -949,7 +948,6 @@ static int ghes_notify_nmi(unsigned int cmd, struct pt_regs *regs)
 
 		sev = ghes_severity(ghes->estatus->error_severity);
 		if (sev >= GHES_SEV_PANIC) {
-			oops_begin();
 			ghes_print_queued_estatus();
 			__ghes_panic(ghes);
 		}