linux-kernel - [PATCH v10 04/50] x86/cpufeatures: Add SEV-SNP CPU feature

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Message-ID: <20231016132819.1002933-5-michael.roth@amd.com>
Date:   Mon, 16 Oct 2023 08:27:33 -0500
From:   Michael Roth <michael.roth@....com>
To:     <kvm@...r.kernel.org>
CC:     <linux-coco@...ts.linux.dev>, <linux-mm@...ck.org>,
        <linux-crypto@...r.kernel.org>, <x86@...nel.org>,
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        <nikunj.dadhania@....com>, <pankaj.gupta@....com>,
        <liam.merwick@...cle.com>, <zhi.a.wang@...el.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Jarkko Sakkinen <jarkko@...fian.com>,
        Ashish Kalra <Ashish.Kalra@....com>
Subject: [PATCH v10 04/50] x86/cpufeatures: Add SEV-SNP CPU feature

From: Brijesh Singh <brijesh.singh@....com>

Add CPU feature detection for Secure Encrypted Virtualization with
Secure Nested Paging. This feature adds a strong memory integrity
protection to help prevent malicious hypervisor-based attacks like
data replay, memory re-mapping, and more.

Signed-off-by: Brijesh Singh <brijesh.singh@....com>
Signed-off-by: Jarkko Sakkinen <jarkko@...fian.com>
Signed-off-by: Ashish Kalra <Ashish.Kalra@....com>
Signed-off-by: Michael Roth <michael.roth@....com>
---
 arch/x86/include/asm/cpufeatures.h       | 1 +
 arch/x86/kernel/cpu/amd.c                | 5 +++--
 tools/arch/x86/include/asm/cpufeatures.h | 1 +
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 58cb9495e40f..1640cedd77f1 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -437,6 +437,7 @@
 #define X86_FEATURE_SEV			(19*32+ 1) /* AMD Secure Encrypted Virtualization */
 #define X86_FEATURE_VM_PAGE_FLUSH	(19*32+ 2) /* "" VM Page Flush MSR is supported */
 #define X86_FEATURE_SEV_ES		(19*32+ 3) /* AMD Secure Encrypted Virtualization - Encrypted State */
+#define X86_FEATURE_SEV_SNP		(19*32+ 4) /* AMD Secure Encrypted Virtualization - Secure Nested Paging */
 #define X86_FEATURE_V_TSC_AUX		(19*32+ 9) /* "" Virtual TSC_AUX */
 #define X86_FEATURE_SME_COHERENT	(19*32+10) /* "" AMD hardware-enforced cache coherency */
 #define X86_FEATURE_DEBUG_SWAP		(19*32+14) /* AMD SEV-ES full debug state swap support */
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index dd8379d84445..14ee7f750cc7 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -630,8 +630,8 @@ static void early_detect_mem_encrypt(struct cpuinfo_x86 *c)
 	 *	      SME feature (set in scattered.c).
 	 *	      If the kernel has not enabled SME via any means then
 	 *	      don't advertise the SME feature.
-	 *   For SEV: If BIOS has not enabled SEV then don't advertise the
-	 *            SEV and SEV_ES feature (set in scattered.c).
+	 *   For SEV: If BIOS has not enabled SEV then don't advertise SEV and
+	 *	      any additional functionality based on it.
 	 *
 	 *   In all cases, since support for SME and SEV requires long mode,
 	 *   don't advertise the feature under CONFIG_X86_32.
@@ -666,6 +666,7 @@ static void early_detect_mem_encrypt(struct cpuinfo_x86 *c)
 clear_sev:
 		setup_clear_cpu_cap(X86_FEATURE_SEV);
 		setup_clear_cpu_cap(X86_FEATURE_SEV_ES);
+		setup_clear_cpu_cap(X86_FEATURE_SEV_SNP);
 	}
 }
 
diff --git a/tools/arch/x86/include/asm/cpufeatures.h b/tools/arch/x86/include/asm/cpufeatures.h
index 798e60b5454b..669f45eefa0c 100644
--- a/tools/arch/x86/include/asm/cpufeatures.h
+++ b/tools/arch/x86/include/asm/cpufeatures.h
@@ -432,6 +432,7 @@
 #define X86_FEATURE_SEV			(19*32+ 1) /* AMD Secure Encrypted Virtualization */
 #define X86_FEATURE_VM_PAGE_FLUSH	(19*32+ 2) /* "" VM Page Flush MSR is supported */
 #define X86_FEATURE_SEV_ES		(19*32+ 3) /* AMD Secure Encrypted Virtualization - Encrypted State */
+#define X86_FEATURE_SEV_SNP		(19*32+ 4) /* AMD Secure Encrypted Virtualization - Secure Nested Paging */
 #define X86_FEATURE_V_TSC_AUX		(19*32+ 9) /* "" Virtual TSC_AUX */
 #define X86_FEATURE_SME_COHERENT	(19*32+10) /* "" AMD hardware-enforced cache coherency */
 #define X86_FEATURE_DEBUG_SWAP		(19*32+14) /* AMD SEV-ES full debug state swap support */
-- 
2.25.1