[PATCH v2 03/12] x86/sev: Add an x86 version of prot_guest_has()

Tom Lendacky
2021-08-13T17:00:16Z

Introduce an x86 version of the prot_guest_has() function. This will be
used in the more generic x86 code to replace vendor specific calls like
sev_active(), etc.

While the name suggests this is intended mainly for guests, it will
also be used for host memory encryption checks in place of sme_active().

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Joerg Roedel <jroedel@suse.de>
Co-developed-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Co-developed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
arch/x86/Kconfig | 1 +
arch/x86/include/asm/mem_encrypt.h | 2 ++
arch/x86/include/asm/protected_guest.h | 29 ++++++++++++++++++++++++++
arch/x86/mm/mem_encrypt.c | 25 ++++++++++++++++++++++
include/linux/protected_guest.h | 5 +++++
5 files changed, 62 insertions(+)
create mode 100644 arch/x86/include/asm/protected_guest.h

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 421fa9e38c60..82e5fb713261 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1514,6 +1514,7 @@ config AMD_MEM_ENCRYPT
select ARCH_HAS_FORCE_DMA_UNENCRYPTED
select INSTRUCTION_DECODER
select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
+ select ARCH_HAS_PROTECTED_GUEST
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..a46d47662772 100644
--- a/arch/x86/include/asm/mem_encrypt.h
+++ b/arch/x86/include/asm/mem_encrypt.h
@@ -53,6 +53,7 @@ void __init sev_es_init_vc_handling(void);
bool sme_active(void);
bool sev_active(void);
bool sev_es_active(void);
+bool amd_prot_guest_has(unsigned int attr);

#define __bss_decrypted __section(".bss..decrypted")

@@ -78,6 +79,7 @@ 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_prot_guest_has(unsigned int attr) { return false; }

static inline int __init
early_set_memory_decrypted(unsigned long vaddr, unsigned long size) { return 0; }
diff --git a/arch/x86/include/asm/protected_guest.h b/arch/x86/include/asm/protected_guest.h
new file mode 100644
index 000000000000..51e4eefd9542
--- /dev/null
+++ b/arch/x86/include/asm/protected_guest.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Protected Guest (and Host) Capability checks
+ *
+ * Copyright (C) 2021 Advanced Micro Devices, Inc.
+ *
+ * Author: Tom Lendacky <thomas.lendacky@amd.com>
+ */
+
+#ifndef _X86_PROTECTED_GUEST_H
+#define _X86_PROTECTED_GUEST_H
+
+#include <linux/mem_encrypt.h>
+
+#ifndef __ASSEMBLY__
+
+static inline bool prot_guest_has(unsigned int attr)
+{
+#ifdef CONFIG_AMD_MEM_ENCRYPT
+ if (sme_me_mask)
+ return amd_prot_guest_has(attr);
+#endif
+
+ return false;
+}
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _X86_PROTECTED_GUEST_H */
diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
index ff08dc463634..edc67ddf065d 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/protected_guest.h>

#include <asm/tlbflush.h>
#include <asm/fixmap.h>
@@ -389,6 +390,30 @@ bool noinstr sev_es_active(void)
return sev_status & MSR_AMD64_SEV_ES_ENABLED;
}

+bool amd_prot_guest_has(unsigned int attr)
+{
+ switch (attr) {
+ case PATTR_MEM_ENCRYPT:
+ return sme_me_mask != 0;
+
+ case PATTR_SME:
+ case PATTR_HOST_MEM_ENCRYPT:
+ return sme_active();
+
+ case PATTR_SEV:
+ case PATTR_GUEST_MEM_ENCRYPT:
+ return sev_active();
+
+ case PATTR_SEV_ES:
+ case PATTR_GUEST_PROT_STATE:
+ return sev_es_active();
+
+ default:
+ return false;
+ }
+}
+EXPORT_SYMBOL_GPL(amd_prot_guest_has);
+
/* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */
bool force_dma_unencrypted(struct device *dev)
{
diff --git a/include/linux/protected_guest.h b/include/linux/protected_guest.h
index 43d4dde94793..5ddef1b6a2ea 100644
--- a/include/linux/protected_guest.h
+++ b/include/linux/protected_guest.h
@@ -20,6 +20,11 @@
#define PATTR_GUEST_MEM_ENCRYPT 2 /* Guest encrypted memory */
#define PATTR_GUEST_PROT_STATE 3 /* Guest encrypted state */

+/* 0x800 - 0x8ff reserved for AMD */
+#define PATTR_SME 0x800
+#define PATTR_SEV 0x801
+#define PATTR_SEV_ES 0x802
+
#ifdef CONFIG_ARCH_HAS_PROTECTED_GUEST

#include <asm/protected_guest.h>
--
2.32.0