Re: [PATCH v4 2/3] efi: Reserve confidential computing secret area
From: Greg KH <gregkh@linuxfoundation.org>
Date: 2021-10-20 06:44:13
Also in:
linux-efi, linux-security-module, lkml
On Wed, Oct 20, 2021 at 06:14:07AM +0000, Dov Murik wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- arch/x86/platform/efi/efi.c | 3 +++ drivers/firmware/efi/Makefile | 1 + drivers/firmware/efi/coco.c | 41 +++++++++++++++++++++++++++++++++++ drivers/firmware/efi/efi.c | 8 +++++++ include/linux/efi.h | 10 +++++++++ 5 files changed, 63 insertions(+) create mode 100644 drivers/firmware/efi/coco.cdiff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index 147c30a81f15..1591d67e0bcd 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c@@ -93,6 +93,9 @@ static const unsigned long * const efi_tables[] = { #ifdef CONFIG_LOAD_UEFI_KEYS &efi.mokvar_table, #endif +#ifdef CONFIG_EFI_COCO_SECRET + &efi.coco_secret, +#endif }; u64 efi_setup; /* efi setup_data physical address */diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile index c02ff25dd477..49c4a8c0bfc4 100644 --- a/drivers/firmware/efi/Makefile +++ b/drivers/firmware/efi/Makefile@@ -32,6 +32,7 @@ obj-$(CONFIG_APPLE_PROPERTIES) += apple-properties.o obj-$(CONFIG_EFI_RCI2_TABLE) += rci2-table.o obj-$(CONFIG_EFI_EMBEDDED_FIRMWARE) += embedded-firmware.o obj-$(CONFIG_LOAD_UEFI_KEYS) += mokvar-table.o +obj-$(CONFIG_EFI_COCO_SECRET) += coco.o fake_map-y += fake_mem.o fake_map-$(CONFIG_X86) += x86_fake_mem.odiff --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@linux.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");
When kernel code works properly, it is quiet. Why do you need to print this out at every boot?
+ + early_memunmap(secret_area, sizeof(*secret_area)); + return 0; +}
And again, when is this memory freed when shutting down? thanks, greg k-h