linux-kernel - [PATCH 61/62] x86/cpufeature: Add SEV_ES

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Date:   Tue, 11 Feb 2020 14:52:55 +0100
From:   Joerg Roedel <joro@...tes.org>
To:     x86@...nel.org
Cc:     hpa@...or.com, Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Hellstrom <thellstrom@...are.com>,
        Jiri Slaby <jslaby@...e.cz>,
        Dan Williams <dan.j.williams@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Juergen Gross <jgross@...e.com>,
        Kees Cook <keescook@...omium.org>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        Joerg Roedel <joro@...tes.org>, Joerg Roedel <jroedel@...e.de>
Subject: [PATCH 61/62] x86/cpufeature: Add SEV_ES_GUEST CPU Feature

From: Joerg Roedel <jroedel@...e.de>

The feature bit will indicate whether the kernel runs as an SEV-ES
guest. This can be used to apply alternatives at boot for SEV-ES guests
and provides a way for user-space to detect whether it runs as an SEV-ES
guest.

Signed-off-by: Joerg Roedel <jroedel@...e.de>
---
 arch/x86/include/asm/cpufeatures.h | 1 +
 arch/x86/kernel/cpu/amd.c          | 6 +++++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 26e4ee209f7b..e864327812e2 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -234,6 +234,7 @@
 #define X86_FEATURE_EPT_AD		( 8*32+17) /* Intel Extended Page Table access-dirty bit */
 #define X86_FEATURE_VMCALL		( 8*32+18) /* "" Hypervisor supports the VMCALL instruction */
 #define X86_FEATURE_VMW_VMMCALL		( 8*32+19) /* "" VMware prefers VMMCALL hypercall instruction */
+#define X86_FEATURE_SEV_ES_GUEST	( 8*32+20) /* SEV-ES Guest */
 
 /* Intel-defined CPU features, CPUID level 0x00000007:0 (EBX), word 9 */
 #define X86_FEATURE_FSGSBASE		( 9*32+ 0) /* RDFSBASE, WRFSBASE, RDGSBASE, WRGSBASE instructions*/
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index aad2223862ef..a1eb39153771 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -484,7 +484,6 @@ static void early_init_amd_mc(struct cpuinfo_x86 *c)
 
 static void bsp_init_amd(struct cpuinfo_x86 *c)
 {
-
 #ifdef CONFIG_X86_64
 	if (c->x86 >= 0xf) {
 		unsigned long long tseg;
@@ -614,6 +613,11 @@ static void early_detect_mem_encrypt(struct cpuinfo_x86 *c)
 		setup_clear_cpu_cap(X86_FEATURE_SEV);
 		setup_clear_cpu_cap(X86_FEATURE_SEV_ES);
 	}
+
+	if (!rdmsrl_safe(MSR_AMD64_SEV, &msr)) {
+		if (msr & MSR_AMD64_SEV_ES_ENABLED)
+			set_cpu_cap(c, X86_FEATURE_SEV_ES_GUEST);
+	}
 }
 
 static void early_init_amd(struct cpuinfo_x86 *c)
-- 
2.17.1