From 8c9c509baf660f1062bc758c26008b7f9bbc39f3 Mon Sep 17 00:00:00 2001 From: Michael Roth Date: Thu, 24 Feb 2022 10:56:13 -0600 Subject: [PATCH] x86/boot: Add a pointer to Confidential Computing blob in bootparams The previously defined Confidential Computing blob is provided to the kernel via a setup_data structure or EFI config table entry. Currently, these are both checked for by boot/compressed kernel to access the CPUID table address within it for use with SEV-SNP CPUID enforcement. To also enable that enforcement for the run-time kernel, similar access to the CPUID table is needed early on while it's still using the identity-mapped page table set up by boot/compressed, where global pointers need to be accessed via fixup_pointer(). This isn't much of an issue for accessing setup_data, and the EFI config table helper code currently used in boot/compressed *could* be used in this case as well since they both rely on identity-mapping. However, it has some reliance on EFI helpers/string constants that would need to be accessed via fixup_pointer(), and fixing it up while making it shareable between boot/compressed and run-time kernel is fragile and introduces a good bit of ugliness. Instead, add a boot_params->cc_blob_address pointer that the boot/compressed kernel can initialize so that the run-time kernel can access the CC blob from there instead of re-scanning the EFI config table. Also document these in Documentation/x86/zero-page.rst. While there, add missing documentation for the acpi_rsdp_addr field, which serves a similar purpose in providing the run-time kernel a pointer to the ACPI RSDP table so that it does not need to [re-]scan the EFI configuration table. [ bp: Fix typos, massage commit message. ] Signed-off-by: Michael Roth Signed-off-by: Brijesh Singh Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/20220307213356.2797205-34-brijesh.singh@amd.com --- Documentation/x86/zero-page.rst | 2 ++ arch/x86/include/asm/bootparam_utils.h | 1 + arch/x86/include/uapi/asm/bootparam.h | 3 ++- 3 files changed, 5 insertions(+), 1 deletion(-) diff --git a/Documentation/x86/zero-page.rst b/Documentation/x86/zero-page.rst index f088f5881666..45aa9cceb4f1 100644 --- a/Documentation/x86/zero-page.rst +++ b/Documentation/x86/zero-page.rst @@ -19,6 +19,7 @@ Offset/Size Proto Name Meaning 058/008 ALL tboot_addr Physical address of tboot shared page 060/010 ALL ist_info Intel SpeedStep (IST) BIOS support information (struct ist_info) +070/008 ALL acpi_rsdp_addr Physical address of ACPI RSDP table 080/010 ALL hd0_info hd0 disk parameter, OBSOLETE!! 090/010 ALL hd1_info hd1 disk parameter, OBSOLETE!! 0A0/010 ALL sys_desc_table System description table (struct sys_desc_table), @@ -27,6 +28,7 @@ Offset/Size Proto Name Meaning 0C0/004 ALL ext_ramdisk_image ramdisk_image high 32bits 0C4/004 ALL ext_ramdisk_size ramdisk_size high 32bits 0C8/004 ALL ext_cmd_line_ptr cmd_line_ptr high 32bits +13C/004 ALL cc_blob_address Physical address of Confidential Computing blob 140/080 ALL edid_info Video mode setup (struct edid_info) 1C0/020 ALL efi_info EFI 32 information (struct efi_info) 1E0/004 ALL alt_mem_k Alternative mem check, in KB diff --git a/arch/x86/include/asm/bootparam_utils.h b/arch/x86/include/asm/bootparam_utils.h index 981fe923a59f..53e9b0620d96 100644 --- a/arch/x86/include/asm/bootparam_utils.h +++ b/arch/x86/include/asm/bootparam_utils.h @@ -74,6 +74,7 @@ static void sanitize_boot_params(struct boot_params *boot_params) BOOT_PARAM_PRESERVE(hdr), BOOT_PARAM_PRESERVE(e820_table), BOOT_PARAM_PRESERVE(eddbuf), + BOOT_PARAM_PRESERVE(cc_blob_address), }; memset(&scratch, 0, sizeof(scratch)); diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h index 1ac5acca72ce..bea5cdcdf532 100644 --- a/arch/x86/include/uapi/asm/bootparam.h +++ b/arch/x86/include/uapi/asm/bootparam.h @@ -188,7 +188,8 @@ struct boot_params { __u32 ext_ramdisk_image; /* 0x0c0 */ __u32 ext_ramdisk_size; /* 0x0c4 */ __u32 ext_cmd_line_ptr; /* 0x0c8 */ - __u8 _pad4[116]; /* 0x0cc */ + __u8 _pad4[112]; /* 0x0cc */ + __u32 cc_blob_address; /* 0x13c */ struct edid_info edid_info; /* 0x140 */ struct efi_info efi_info; /* 0x1c0 */ __u32 alt_mem_k; /* 0x1e0 */