[PATCH] efistub: add efi=quiet parameter to selectively silence efistub alone

[Hendrik 'T4cC0re' Meyer <linux@t4c.dev>]

While the general `quiet` kernel parameter is available to silence
output from the efistub, setting this comes with side-effects.
This patch adds a parameter efi=quiet to selectively set the loglevel
for the stub alone to quiet, as the polar oppoosite to efi=debug.

Signed-off-by: Hendrik 'T4cC0re' Meyer <linux@t4c.dev>
---
 Documentation/admin-guide/kernel-parameters.txt | 3 ++-
 drivers/firmware/efi/libstub/efi-stub-helper.c  | 2 ++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 3872bc6ec..94a2f6ae7 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1454,7 +1454,7 @@
 	efi=		[EFI,EARLY]
 			Format: { "debug", "disable_early_pci_dma",
 				  "nochunk", "noruntime", "nosoftreserve",
-				  "novamap", "no_disable_early_pci_dma" }
+				  "novamap", "no_disable_early_pci_dma", "quiet" }
 			debug: enable misc debug output.
 			disable_early_pci_dma: disable the busmaster bit on all
 			PCI bridges while in the EFI boot stub.
@@ -1471,6 +1471,7 @@
 			novamap: do not call SetVirtualAddressMap().
 			no_disable_early_pci_dma: Leave the busmaster bit set
 			on all PCI bridges while in the EFI boot stub
+			quiet: disable most log messages.
 
 	efi_no_storage_paranoia [EFI,X86,EARLY]
 			Using this parameter you can use more than 50% of
diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c
index c0c81ca42..b8ad629cc 100644
--- a/drivers/firmware/efi/libstub/efi-stub-helper.c
+++ b/drivers/firmware/efi/libstub/efi-stub-helper.c
@@ -97,6 +97,8 @@ efi_status_t efi_parse_options(char const *cmdline)
 				efi_disable_pci_dma = false;
 			if (parse_option_str(val, "debug"))
 				efi_loglevel = CONSOLE_LOGLEVEL_DEBUG;
+			if (parse_option_str(val, "quiet"))
+				efi_loglevel = CONSOLE_LOGLEVEL_QUIET;
 		} else if (!strcmp(param, "video") &&
 			   val && strstarts(val, "efifb:")) {
 			efi_parse_option_graphics(val + strlen("efifb:"));
-- 
2.47.1