[PATCH v3 3/8] x86/sev: Add an x86 version of cc_platform_has()

[Tom Lendacky <thomas.lendacky@xxxxxxx>]

Introduce an x86 version of the cc_platform_has() function. This will be
used to replace vendor specific calls like sme_active(), sev_active(),
etc.

Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Co-developed-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Co-developed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
---
 arch/x86/Kconfig                   |  1 +
 arch/x86/include/asm/mem_encrypt.h |  3 +++
 arch/x86/kernel/Makefile           |  3 +++
 arch/x86/kernel/cc_platform.c      | 21 +++++++++++++++++++++
 arch/x86/mm/mem_encrypt.c          | 21 +++++++++++++++++++++
 5 files changed, 49 insertions(+)
 create mode 100644 arch/x86/kernel/cc_platform.c

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 4e001bbbb425..2b2a9639d8ae 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1513,6 +1513,7 @@ config AMD_MEM_ENCRYPT
 	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
 	select INSTRUCTION_DECODER
 	select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
+	select ARCH_HAS_CC_PLATFORM
 	help
 	  Say yes to enable support for the encryption of system memory.
 	  This requires an AMD processor that supports Secure Memory
diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h
index 9c80c68d75b5..3d8a5e8b2e3f 100644
--- a/arch/x86/include/asm/mem_encrypt.h
+++ b/arch/x86/include/asm/mem_encrypt.h
@@ -13,6 +13,7 @@
 #ifndef __ASSEMBLY__
 
 #include <linux/init.h>
+#include <linux/cc_platform.h>
 
 #include <asm/bootparam.h>
 
@@ -53,6 +54,7 @@ void __init sev_es_init_vc_handling(void);
 bool sme_active(void);
 bool sev_active(void);
 bool sev_es_active(void);
+bool amd_cc_platform_has(enum cc_attr attr);
 
 #define __bss_decrypted __section(".bss..decrypted")
 
@@ -78,6 +80,7 @@ static inline void sev_es_init_vc_handling(void) { }
 static inline bool sme_active(void) { return false; }
 static inline bool sev_active(void) { return false; }
 static inline bool sev_es_active(void) { return false; }
+static inline bool amd_cc_platform_has(enum cc_attr attr) { return false; }
 
 static inline int __init
 early_set_memory_decrypted(unsigned long vaddr, unsigned long size) { return 0; }
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 8f4e8fa6ed75..f91403a78594 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -147,6 +147,9 @@ obj-$(CONFIG_UNWINDER_FRAME_POINTER)	+= unwind_frame.o
 obj-$(CONFIG_UNWINDER_GUESS)		+= unwind_guess.o
 
 obj-$(CONFIG_AMD_MEM_ENCRYPT)		+= sev.o
+
+obj-$(CONFIG_ARCH_HAS_CC_PLATFORM)	+= cc_platform.o
+
 ###
 # 64 bit specific files
 ifeq ($(CONFIG_X86_64),y)
diff --git a/arch/x86/kernel/cc_platform.c b/arch/x86/kernel/cc_platform.c
new file mode 100644
index 000000000000..3c9bacd3c3f3
--- /dev/null
+++ b/arch/x86/kernel/cc_platform.c
@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Confidential Computing Platform Capability checks
+ *
+ * Copyright (C) 2021 Advanced Micro Devices, Inc.
+ *
+ * Author: Tom Lendacky <thomas.lendacky@xxxxxxx>
+ */
+
+#include <linux/export.h>
+#include <linux/cc_platform.h>
+#include <linux/mem_encrypt.h>
+
+bool cc_platform_has(enum cc_attr attr)
+{
+	if (sme_me_mask)
+		return amd_cc_platform_has(attr);
+
+	return false;
+}
+EXPORT_SYMBOL_GPL(cc_platform_has);
diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
index ff08dc463634..18fe19916bc3 100644
--- a/arch/x86/mm/mem_encrypt.c
+++ b/arch/x86/mm/mem_encrypt.c
@@ -20,6 +20,7 @@
 #include <linux/bitops.h>
 #include <linux/dma-mapping.h>
 #include <linux/virtio_config.h>
+#include <linux/cc_platform.h>
 
 #include <asm/tlbflush.h>
 #include <asm/fixmap.h>
@@ -389,6 +390,26 @@ bool noinstr sev_es_active(void)
 	return sev_status & MSR_AMD64_SEV_ES_ENABLED;
 }
 
+bool amd_cc_platform_has(enum cc_attr attr)
+{
+	switch (attr) {
+	case CC_ATTR_MEM_ENCRYPT:
+		return sme_me_mask != 0;
+
+	case CC_ATTR_HOST_MEM_ENCRYPT:
+		return sme_active();
+
+	case CC_ATTR_GUEST_MEM_ENCRYPT:
+		return sev_active();
+
+	case CC_ATTR_GUEST_STATE_ENCRYPT:
+		return sev_es_active();
+
+	default:
+		return false;
+	}
+}
+
 /* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */
 bool force_dma_unencrypted(struct device *dev)
 {
-- 
2.33.0