linux-kernel - [PATCH Part1 RFC v4 28/36] x86/compressed/64: store Confidential Computing blob address in bootparams

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed,  7 Jul 2021 13:14:58 -0500
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,
        linux-crypto@...r.kernel.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>,
        Wanpeng Li <wanpengli@...cent.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>, tony.luck@...el.com,
        npmccallum@...hat.com, brijesh.ksingh@...il.com,
        Brijesh Singh <brijesh.singh@....com>
Subject: [PATCH Part1 RFC v4 28/36] x86/compressed/64: store Confidential Computing blob address in bootparams

From: Michael Roth <michael.roth@....com>

When the Confidential Computing blob is located by the boot/compressed
kernel, store a pointer to it in bootparams->cc_blob_address to avoid
the need for the run-time kernel to rescan the EFI config table to find
it again.

Since this function is also shared by the run-time kernel, this patch
also adds the logic to make use of bootparams->cc_blob_address when it
has been initialized.

Signed-off-by: Michael Roth <michael.roth@....com>
Signed-off-by: Brijesh Singh <brijesh.singh@....com>
---
 arch/x86/kernel/sev-shared.c | 38 +++++++++++++++++++++++++-----------
 1 file changed, 27 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c
index 5e0e8e208a8c..23328727caf4 100644
--- a/arch/x86/kernel/sev-shared.c
+++ b/arch/x86/kernel/sev-shared.c
@@ -820,7 +820,6 @@ static enum es_result vc_handle_rdtsc(struct ghcb *ghcb,
 	return ES_OK;
 }
 
-#ifdef BOOT_COMPRESSED
 static struct setup_data *get_cc_setup_data(struct boot_params *bp)
 {
 	struct setup_data *hdr = (struct setup_data *)bp->hdr.setup_data;
@@ -840,6 +839,16 @@ static struct setup_data *get_cc_setup_data(struct boot_params *bp)
  *   1) Search for CC blob in the following order/precedence:
  *      - via linux boot protocol / setup_data entry
  *      - via EFI configuration table
+ *   2) If found, initialize boot_params->cc_blob_address to point to the
+ *      blob so that uncompressed kernel can easily access it during very
+ *      early boot without the need to re-parse EFI config table
+ *   3) Return a pointer to the CC blob, NULL otherwise.
+ *
+ * For run-time/uncompressed kernel:
+ *
+ *   1) Search for CC blob in the following order/precedence:
+ *      - via linux boot protocol / setup_data entry
+ *      - via boot_params->cc_blob_address
  *   2) Return a pointer to the CC blob, NULL otherwise.
  */
 static struct cc_blob_sev_info *sev_snp_probe_cc_blob(struct boot_params *bp)
@@ -857,27 +866,34 @@ static struct cc_blob_sev_info *sev_snp_probe_cc_blob(struct boot_params *bp)
 		goto out_verify;
 	}
 
+#ifdef __BOOT_COMPRESSED
 	/* CC blob isn't in setup_data, see if it's in the EFI config table */
 	(void)efi_bp_find_vendor_table(bp, EFI_CC_BLOB_GUID,
 				       (unsigned long *)&cc_info);
+#else
+	/*
+	 * CC blob isn't in setup_data, see if boot kernel passed it via
+	 * boot_params.
+	 */
+	if (bp->cc_blob_address)
+		cc_info = (struct cc_blob_sev_info *)(unsigned long)bp->cc_blob_address;
+#endif
 
 out_verify:
 	/* CC blob should be either valid or not present. Fail otherwise. */
 	if (cc_info && cc_info->magic != CC_BLOB_SEV_HDR_MAGIC)
 		sev_es_terminate(1, GHCB_SNP_UNSUPPORTED);
 
+#ifdef __BOOT_COMPRESSED
+	/*
+	 * Pass run-time kernel a pointer to CC info via boot_params for easier
+	 * access during early boot.
+	 */
+	bp->cc_blob_address = (u32)(unsigned long)cc_info;
+#endif
+
 	return cc_info;
 }
-#else
-/*
- * Probing for CC blob for run-time kernel will be enabled in a subsequent
- * patch. For now we need to stub this out.
- */
-static struct cc_blob_sev_info *sev_snp_probe_cc_blob(struct boot_params *bp)
-{
-	return NULL;
-}
-#endif
 
 /*
  * Initial set up of CPUID table when running identity-mapped.
-- 
2.17.1