efi/libstub: Add generic support for parsing mem_encrypt=

commit 7205f06e847422b66c1506eee01b9998ffc75d76 upstream.

Parse the mem_encrypt= command line parameter from the EFI stub if
CONFIG_ARCH_HAS_MEM_ENCRYPT=y, so that it can be passed to the early
boot code by the arch code in the stub.

This avoids the need for the core kernel to do any string parsing very
early in the boot.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lore.kernel.org/r/20240227151907.387873-16-ardb+git@google.com
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c
index bfa30625f5d03167219a0f62ffc437436ff06693..3dc2f9aaf08db020a74201d2462c2fd2efecef46 100644 (file)
--- a/drivers/firmware/efi/libstub/efi-stub-helper.c
+++ b/drivers/firmware/efi/libstub/efi-stub-helper.c
@@ -24,6 +24,8 @@ static bool efi_noinitrd;
 static bool efi_nosoftreserve;
 static bool efi_disable_pci_dma = IS_ENABLED(CONFIG_EFI_DISABLE_PCI_DMA);
 
+int efi_mem_encrypt;
+
 bool __pure __efi_soft_reserve_enabled(void)
 {
        return !efi_nosoftreserve;
@@ -75,6 +77,12 @@ efi_status_t efi_parse_options(char const *cmdline)
                        efi_noinitrd = true;
                } else if (IS_ENABLED(CONFIG_X86_64) && !strcmp(param, "no5lvl")) {
                        efi_no5lvl = true;
+               } else if (IS_ENABLED(CONFIG_ARCH_HAS_MEM_ENCRYPT) &&
+                          !strcmp(param, "mem_encrypt") && val) {
+                       if (parse_option_str(val, "on"))
+                               efi_mem_encrypt = 1;
+                       else if (parse_option_str(val, "off"))
+                               efi_mem_encrypt = -1;
                } else if (!strcmp(param, "efi") && val) {
                        efi_nochunk = parse_option_str(val, "nochunk");
                        efi_novamap |= parse_option_str(val, "novamap");

diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
index c04b82ea40f2169b6764ff69a14ff3acc5a8795d..fc18fd649ed771a9edad143b263bd4f887f5f467 100644 (file)
--- a/drivers/firmware/efi/libstub/efistub.h
+++ b/drivers/firmware/efi/libstub/efistub.h
@@ -37,8 +37,8 @@ extern bool efi_no5lvl;
 extern bool efi_nochunk;
 extern bool efi_nokaslr;
 extern int efi_loglevel;
+extern int efi_mem_encrypt;
 extern bool efi_novamap;
-
 extern const efi_system_table_t *efi_system_table;
 
 typedef union efi_dxe_services_table efi_dxe_services_table_t;