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authorMichael Roth <michael.roth@amd.com>2022-02-24 10:56:13 -0600
committerBorislav Petkov <bp@suse.de>2022-04-07 16:47:11 +0200
commit8c9c509baf660f1062bc758c26008b7f9bbc39f3 (patch)
treed9c9432e6c0810e8cc9a1ec677d55cb8745c1a6b /Documentation/x86
parentee0bfa08a345370df28c07288e886abcbaac481f (diff)
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 <michael.roth@amd.com> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/20220307213356.2797205-34-brijesh.singh@amd.com
Diffstat (limited to 'Documentation/x86')
-rw-r--r--Documentation/x86/zero-page.rst2
1 files changed, 2 insertions, 0 deletions
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