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Message-ID: <20220128171804.569796-33-brijesh.singh@amd.com>
Date: Fri, 28 Jan 2022 11:17:53 -0600
From: Brijesh Singh <brijesh.singh@....com>
To: <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
<kvm@...r.kernel.org>, <linux-efi@...r.kernel.org>,
<platform-driver-x86@...r.kernel.org>,
<linux-coco@...ts.linux.dev>, <linux-mm@...ck.org>
CC: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Joerg Roedel <jroedel@...e.de>,
Tom Lendacky <thomas.lendacky@....com>,
"H. Peter Anvin" <hpa@...or.com>, Ard Biesheuvel <ardb@...nel.org>,
Paolo Bonzini <pbonzini@...hat.com>,
Sean Christopherson <seanjc@...gle.com>,
"Vitaly Kuznetsov" <vkuznets@...hat.com>,
Jim Mattson <jmattson@...gle.com>,
"Andy Lutomirski" <luto@...nel.org>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Sergio Lopez <slp@...hat.com>, Peter Gonda <pgonda@...gle.com>,
"Peter Zijlstra" <peterz@...radead.org>,
Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
David Rientjes <rientjes@...gle.com>,
Dov Murik <dovmurik@...ux.ibm.com>,
Tobin Feldman-Fitzthum <tobin@....com>,
Borislav Petkov <bp@...en8.de>,
Michael Roth <michael.roth@....com>,
Vlastimil Babka <vbabka@...e.cz>,
"Kirill A . Shutemov" <kirill@...temov.name>,
Andi Kleen <ak@...ux.intel.com>,
"Dr . David Alan Gilbert" <dgilbert@...hat.com>,
<brijesh.ksingh@...il.com>, <tony.luck@...el.com>,
<marcorr@...gle.com>, <sathyanarayanan.kuppuswamy@...ux.intel.com>,
Brijesh Singh <brijesh.singh@....com>
Subject: [PATCH v9 32/43] x86/boot: Add a pointer to Confidential Computing blob in bootparams
From: Michael Roth <michael.roth@....com>
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 SEV-SNP CPUID enforcement for the run-time kernel,
similar early 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 uglyness.
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.
Signed-off-by: Michael Roth <michael.roth@....com>
Signed-off-by: Brijesh Singh <brijesh.singh@....com>
---
arch/x86/include/asm/bootparam_utils.h | 1 +
arch/x86/include/uapi/asm/bootparam.h | 3 ++-
2 files changed, 3 insertions(+), 1 deletion(-)
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 */
--
2.25.1
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