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Message-Id: <20211007061838.1381129-4-dovmurik@linux.ibm.com>
Date: Thu, 7 Oct 2021 06:18:37 +0000
From: Dov Murik <dovmurik@...ux.ibm.com>
To: linux-efi@...r.kernel.org
Cc: Dov Murik <dovmurik@...ux.ibm.com>, Borislav Petkov <bp@...e.de>,
Ashish Kalra <ashish.kalra@....com>,
Brijesh Singh <brijesh.singh@....com>,
Tom Lendacky <thomas.lendacky@....com>,
Ard Biesheuvel <ardb@...nel.org>,
James Morris <jmorris@...ei.org>,
"Serge E. Hallyn" <serge@...lyn.com>,
Andi Kleen <ak@...ux.intel.com>,
Greg KH <gregkh@...uxfoundation.org>,
Andrew Scull <ascull@...gle.com>,
"Dr. David Alan Gilbert" <dgilbert@...hat.com>,
James Bottomley <jejb@...ux.ibm.com>,
Tobin Feldman-Fitzthum <tobin@...ux.ibm.com>,
Jim Cadden <jcadden@....com>,
Daniele Buono <dbuono@...ux.vnet.ibm.com>,
linux-coco@...ts.linux.dev, linux-security-module@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v2 3/4] efi: Reserve confidential computing secret area
When efi-stub copies an EFI-provided confidential computing (coco)
secret area, reserve that memory block for future use within the kernel.
Signed-off-by: Dov Murik <dovmurik@...ux.ibm.com>
---
arch/x86/platform/efi/efi.c | 1 +
drivers/firmware/efi/Makefile | 2 +-
drivers/firmware/efi/coco.c | 41 +++++++++++++++++++++++++++++++++++
drivers/firmware/efi/efi.c | 3 +++
include/linux/efi.h | 3 +++
5 files changed, 49 insertions(+), 1 deletion(-)
create mode 100644 drivers/firmware/efi/coco.c
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 147c30a81f15..35e082e5f603 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -93,6 +93,7 @@ static const unsigned long * const efi_tables[] = {
#ifdef CONFIG_LOAD_UEFI_KEYS
&efi.mokvar_table,
#endif
+ &efi.coco_secret,
};
u64 efi_setup; /* efi setup_data physical address */
diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
index c02ff25dd477..bfd35294703e 100644
--- a/drivers/firmware/efi/Makefile
+++ b/drivers/firmware/efi/Makefile
@@ -12,7 +12,7 @@ KASAN_SANITIZE_runtime-wrappers.o := n
obj-$(CONFIG_ACPI_BGRT) += efi-bgrt.o
obj-$(CONFIG_EFI) += efi.o vars.o reboot.o memattr.o tpm.o
-obj-$(CONFIG_EFI) += memmap.o
+obj-$(CONFIG_EFI) += memmap.o coco.o
ifneq ($(CONFIG_EFI_CAPSULE_LOADER),)
obj-$(CONFIG_EFI) += capsule.o
endif
diff --git a/drivers/firmware/efi/coco.c b/drivers/firmware/efi/coco.c
new file mode 100644
index 000000000000..42f477d6188c
--- /dev/null
+++ b/drivers/firmware/efi/coco.c
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Confidential computing (coco) secret area handling
+ *
+ * Copyright (C) 2021 IBM Corporation
+ * Author: Dov Murik <dovmurik@...ux.ibm.com>
+ */
+
+#define pr_fmt(fmt) "efi: " fmt
+
+#include <linux/efi.h>
+#include <linux/init.h>
+#include <linux/memblock.h>
+#include <asm/early_ioremap.h>
+
+/*
+ * Reserve the confidential computing secret area memory
+ */
+int __init efi_coco_secret_area_reserve(void)
+{
+ struct linux_efi_coco_secret_area *secret_area;
+ unsigned long secret_area_size;
+
+ if (efi.coco_secret == EFI_INVALID_TABLE_ADDR)
+ return 0;
+
+ secret_area = early_memremap(efi.coco_secret, sizeof(*secret_area));
+ if (!secret_area) {
+ pr_err("Failed to map confidential computing secret area\n");
+ efi.coco_secret = EFI_INVALID_TABLE_ADDR;
+ return -ENOMEM;
+ }
+
+ secret_area_size = sizeof(*secret_area) + secret_area->size;
+ memblock_reserve(efi.coco_secret, secret_area_size);
+
+ pr_info("Reserved memory of EFI-provided confidential computing secret area");
+
+ early_memunmap(secret_area, sizeof(*secret_area));
+ return 0;
+}
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 847f33ffc4ae..07e17ad225a6 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -526,6 +526,7 @@ static const efi_config_table_type_t common_tables[] __initconst = {
#ifdef CONFIG_LOAD_UEFI_KEYS
{LINUX_EFI_MOK_VARIABLE_TABLE_GUID, &efi.mokvar_table, "MOKvar" },
#endif
+ {LINUX_EFI_COCO_SECRET_AREA_GUID, &efi.coco_secret, "CocoSecret" },
{},
};
@@ -613,6 +614,8 @@ int __init efi_config_parse_tables(const efi_config_table_t *config_tables,
efi_tpm_eventlog_init();
+ efi_coco_secret_area_reserve();
+
if (mem_reserve != EFI_INVALID_TABLE_ADDR) {
unsigned long prsv = mem_reserve;
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 9021dd521302..e86600af5dfd 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -550,6 +550,7 @@ extern struct efi {
unsigned long tpm_log; /* TPM2 Event Log table */
unsigned long tpm_final_log; /* TPM2 Final Events Log table */
unsigned long mokvar_table; /* MOK variable config table */
+ unsigned long coco_secret; /* Confidential computing secret table */
efi_get_time_t *get_time;
efi_set_time_t *set_time;
@@ -1189,6 +1190,8 @@ extern int efi_tpm_final_log_size;
extern unsigned long rci2_table_phys;
+extern int efi_coco_secret_area_reserve(void);
+
/*
* efi_runtime_service() function identifiers.
* "NONE" is used by efi_recover_from_page_fault() to check if the page
--
2.25.1
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