x86/cpufeatures: Add SEV-ES CPU feature

Add CPU feature detection for Secure Encrypted Virtualization with
Encrypted State. This feature enhances SEV by also encrypting the
guest register state, making it in-accessible to the hypervisor.
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200907131613.12703-6-joro@8bytes.org

arch/x86/include/asm/cpufeatures.h

@@ -236,6 +236,7 @@
 #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		( 8*32+20) /* AMD Secure Encrypted Virtualization - Encrypted State */
 
 /* Intel-defined CPU features, CPUID level 0x00000007:0 (EBX), word 9 */
 #define X86_FEATURE_FSGSBASE		( 9*32+ 0) /* RDFSBASE, WRFSBASE, RDGSBASE, WRGSBASE instructions*/

arch/x86/kernel/cpu/amd.c

@@ -614,7 +614,7 @@ static void early_detect_mem_encrypt(struct cpuinfo_x86 *c)
 	 *	      If BIOS has not enabled SME then don't advertise the
 	 *	      SME feature (set in scattered.c).
 	 *   For SEV: If BIOS has not enabled SEV then don't advertise the
-	 *            SEV feature (set in scattered.c).
+	 *            SEV and SEV_ES feature (set in scattered.c).
 	 *
 	 *   In all cases, since support for SME and SEV requires long mode,
 	 *   don't advertise the feature under CONFIG_X86_32.
@@ -645,6 +645,7 @@ static void early_detect_mem_encrypt(struct cpuinfo_x86 *c)
 		setup_clear_cpu_cap(X86_FEATURE_SME);
 clear_sev:
 		setup_clear_cpu_cap(X86_FEATURE_SEV);
+		setup_clear_cpu_cap(X86_FEATURE_SEV_ES);
 	}
 }
 

arch/x86/kernel/cpu/scattered.c

@@ -41,6 +41,7 @@ static const struct cpuid_bit cpuid_bits[] = {
 	{ X86_FEATURE_MBA,		CPUID_EBX,  6, 0x80000008, 0 },
 	{ X86_FEATURE_SME,		CPUID_EAX,  0, 0x8000001f, 0 },
 	{ X86_FEATURE_SEV,		CPUID_EAX,  1, 0x8000001f, 0 },
+	{ X86_FEATURE_SEV_ES,		CPUID_EAX,  3, 0x8000001f, 0 },
 	{ 0, 0, 0, 0, 0 }
 };