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[78.94.0.50]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3a561a3ce6bsm2078875f8f.49.2025.06.12.07.06.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Jun 2025 07:06:27 -0700 (PDT) From: Michal Gorlas To: Tzung-Bi Shih , Brian Norris , Julius Werner Cc: marcello.bauer@9elements.com, Michal Gorlas , chrome-platform@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [PATCH v1 1/3] firmware: coreboot: support for parsing SMM related informations from coreboot tables Date: Thu, 12 Jun 2025 16:05:48 +0200 Message-ID: <815080fae73a4e879bae4851367ac7c0ad2cd551.1749734094.git.michal.gorlas@9elements.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" coreboot exposes (S)MM related data in the coreboot table. Extends existing= interface, with structure corresponding to (S)MM data, and adds parser. Parser exposes= this data to the modules executed later. Signed-off-by: Michal Gorlas --- drivers/firmware/google/Kconfig | 12 +++++ drivers/firmware/google/Makefile | 3 ++ drivers/firmware/google/coreboot_table.h | 34 ++++++++----- drivers/firmware/google/mm_info.c | 63 ++++++++++++++++++++++++ drivers/firmware/google/mm_payload.h | 58 ++++++++++++++++++++++ 5 files changed, 158 insertions(+), 12 deletions(-) create mode 100644 drivers/firmware/google/mm_info.c create mode 100644 drivers/firmware/google/mm_payload.h diff --git a/drivers/firmware/google/Kconfig b/drivers/firmware/google/Kcon= fig index 41b78f5cb735..5d918c076f25 100644 --- a/drivers/firmware/google/Kconfig +++ b/drivers/firmware/google/Kconfig @@ -81,4 +81,16 @@ config GOOGLE_VPD This option enables the kernel to expose the content of Google VPD under /sys/firmware/vpd. =20 +config COREBOOT_PAYLOAD_MM + tristate "SMI handling in Linux (LinuxBootSMM)" + depends on GOOGLE_COREBOOT_TABLE + help + Enables support for SMI handling by Linux-owned code. + coreboot reserves region for payload-owned SMI handler, the Linux + driver prepares its SMI handler outside of SMRAM, and lets coreboot + know where the handler is placed by issuing an SMI. On this SMI, the + handler is being placed in SMRAM and all supported SMIs from that point + on are handled by Linux-owned SMI handler. + If in doubt, say N. + endif # GOOGLE_FIRMWARE diff --git a/drivers/firmware/google/Makefile b/drivers/firmware/google/Mak= efile index 8151e323cc43..d2a690e8379d 100644 --- a/drivers/firmware/google/Makefile +++ b/drivers/firmware/google/Makefile @@ -12,3 +12,6 @@ obj-$(CONFIG_GOOGLE_CBMEM) +=3D cbmem.o =20 vpd-sysfs-y :=3D vpd.o vpd_decode.o obj-$(CONFIG_GOOGLE_VPD) +=3D vpd-sysfs.o + +# LinuxBootSMM related. +obj-$(CONFIG_COREBOOT_PAYLOAD_MM) +=3D mm_info.o diff --git a/drivers/firmware/google/coreboot_table.h b/drivers/firmware/go= ogle/coreboot_table.h index bb6f0f7299b4..e0b087933c5a 100644 --- a/drivers/firmware/google/coreboot_table.h +++ b/drivers/firmware/google/coreboot_table.h @@ -41,7 +41,6 @@ struct lb_cbmem_ref { }; =20 #define LB_TAG_CBMEM_ENTRY 0x31 - /* Corresponds to LB_TAG_CBMEM_ENTRY */ struct lb_cbmem_entry { u32 tag; @@ -52,6 +51,16 @@ struct lb_cbmem_entry { u32 id; }; =20 +/* Corresponds to LB_TAG_PLD_MM_INTERFACE_INFO */ +#define LB_TAG_PLD_MM_INTERFACE_INFO 0x3b +struct lb_pld_mm_interface_info { + u32 tag; + u32 size; + u8 revision; + u8 requires_long_mode_call; + u8 register_mm_entry_command; +}; + /* Describes framebuffer setup by coreboot */ struct lb_framebuffer { u32 tag; @@ -61,15 +70,15 @@ struct lb_framebuffer { u32 x_resolution; u32 y_resolution; u32 bytes_per_line; - u8 bits_per_pixel; - u8 red_mask_pos; - u8 red_mask_size; - u8 green_mask_pos; - u8 green_mask_size; - u8 blue_mask_pos; - u8 blue_mask_size; - u8 reserved_mask_pos; - u8 reserved_mask_size; + u8 bits_per_pixel; + u8 red_mask_pos; + u8 red_mask_size; + u8 green_mask_pos; + u8 green_mask_size; + u8 blue_mask_pos; + u8 blue_mask_size; + u8 reserved_mask_pos; + u8 reserved_mask_size; }; =20 /* A device, additionally with information from coreboot. */ @@ -80,6 +89,7 @@ struct coreboot_device { struct lb_cbmem_ref cbmem_ref; struct lb_cbmem_entry cbmem_entry; struct lb_framebuffer framebuffer; + struct lb_pld_mm_interface_info mm_info; DECLARE_FLEX_ARRAY(u8, raw); }; }; @@ -112,8 +122,8 @@ void coreboot_driver_unregister(struct coreboot_driver = *driver); * boilerplate. Each module may only use this macro once, and * calling it replaces module_init() and module_exit() */ -#define module_coreboot_driver(__coreboot_driver) \ +#define module_coreboot_driver(__coreboot_driver) \ module_driver(__coreboot_driver, coreboot_driver_register, \ - coreboot_driver_unregister) + coreboot_driver_unregister) =20 #endif /* __COREBOOT_TABLE_H */ diff --git a/drivers/firmware/google/mm_info.c b/drivers/firmware/google/mm= _info.c new file mode 100644 index 000000000000..55bcdc8b8d53 --- /dev/null +++ b/drivers/firmware/google/mm_info.c @@ -0,0 +1,63 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * mm_info.c + * + * Driver for exporting MM payload information from coreboot table. + * + * Copyright 2025 9elements gmbh + * Copyright 2025 Michal Gorlas + */ + +#include +#include +#include + +#include "coreboot_table.h" +#include "mm_payload.h" + +static struct lb_pld_mm_interface_info *mm_cbtable_info; +struct mm_info *mm_info; + +static int mm_driver_probe(struct coreboot_device *dev) +{ + mm_cbtable_info =3D &dev->mm_info; + if (mm_cbtable_info->tag !=3D LB_TAG_PLD_MM_INTERFACE_INFO) + return -ENXIO; + + mm_info =3D kmalloc(sizeof(*mm_info), GFP_KERNEL); + mm_info->revision =3D mm_cbtable_info->revision; + mm_info->requires_long_mode_call =3D + mm_cbtable_info->requires_long_mode_call; + mm_info->register_mm_entry_command =3D + mm_cbtable_info->register_mm_entry_command; + return 0; +} +EXPORT_SYMBOL(mm_info); + +static void mm_driver_remove(struct coreboot_device *dev) +{ + if (mm_info) + kfree(mm_info); +} + +static const struct coreboot_device_id mm_info_ids[] =3D { + { .tag =3D LB_TAG_PLD_MM_INTERFACE_INFO }, + { /* sentinel */ } +}; + +MODULE_DEVICE_TABLE(coreboot, mm_info_ids); + +static struct coreboot_driver mm_driver =3D { + .probe =3D mm_driver_probe, + .remove =3D mm_driver_remove, + .drv =3D { + .name =3D "mm_info", + }, + .id_table =3D mm_info_ids, +}; + +module_coreboot_driver(mm_driver); + +MODULE_AUTHOR("Michal Gorlas "); +MODULE_DESCRIPTION("Driver for exporting MM info from coreboot table"); +MODULE_LICENSE("GPL v2"); diff --git a/drivers/firmware/google/mm_payload.h b/drivers/firmware/google= /mm_payload.h new file mode 100644 index 000000000000..bb2f55c4f240 --- /dev/null +++ b/drivers/firmware/google/mm_payload.h @@ -0,0 +1,58 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * mm_payload.h + * + * Internal header for MM payload driver. + * + * Copyright 2025 9elements gmbh + * Copyright 2025 Michal Gorlas + */ + +#ifndef __MM_PAYLOAD_H +#define __MM_PAYLOAD_H + +#define PAYLOAD_MM_RET_SUCCESS 0 +#define PAYLOAD_MM_RET_FAILURE 1 +#define PAYLOAD_MM_REGISTER_ENTRY 2 + +#define REALMODE_END_SIGNATURE 0x65a22c82 + +struct mm_info { + u8 revision; + u8 requires_long_mode_call; + u8 register_mm_entry_command; +}; + +extern struct mm_info *mm_info; + +#ifndef __ASSEMBLY__ + +#include + +/* This must match data at mm_handler/mm_header.S */ +struct mm_header { + u32 text_start; + u32 mm_entry_32; + u32 mm_entry_64; + u32 mm_signature; + u32 mm_blob_size; +}; + +extern struct mm_header *mm_header; +extern unsigned char mm_blob_end[]; + +extern unsigned char mm_blob[]; +extern unsigned char mm_relocs[]; + +/* + * This has to be under 1MB (see tseg_region.c in coreboot source tree). + * The actual check for this is made in coreboot after we fill the header + * (see above) with the blob size. + */ +static inline size_t mm_payload_size_needed(void) +{ + return mm_blob_end - mm_blob; +} + +#endif /* __ASSEMBLER__ */ +#endif /* __MM_PAYLOAD_H */ --=20 2.49.0