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Subject[PATCH v3 04/11] x86: Introduce generic protected guest abstraction
Date
Add a generic way to check if we run with an encrypted guest,
without requiring x86 specific ifdefs. This can then be used in
non architecture specific code. 

prot_guest_has() is used to check for protected guest feature
flags.

Originally-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
---

Change since v1:
* Introduced PR_GUEST_TDX and PR_GUEST_SEV vendor flags as per
Boris suggestion.
* Replaced is_tdx_guest() with if (boot_cpu_data.x86_vendor ==
X86_VENDOR_INTEL) in prot_guest_has().
* Modified tdx_protected_guest_has() and sev_protected_guest_has()
to support vendor flags.

arch/Kconfig | 3 +++
arch/x86/Kconfig | 2 ++
arch/x86/include/asm/protected_guest.h | 20 +++++++++++++++++
arch/x86/include/asm/sev.h | 3 +++
arch/x86/include/asm/tdx.h | 4 ++++
arch/x86/kernel/sev.c | 17 +++++++++++++++
arch/x86/kernel/tdx.c | 17 +++++++++++++++
include/linux/protected_guest.h | 30 ++++++++++++++++++++++++++
8 files changed, 96 insertions(+)
create mode 100644 arch/x86/include/asm/protected_guest.h
create mode 100644 include/linux/protected_guest.h

diff --git a/arch/Kconfig b/arch/Kconfig
index c45b770d3579..3c5bf55ee752 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -1011,6 +1011,9 @@ config HAVE_ARCH_NVRAM_OPS
config ISA_BUS_API
def_bool ISA

+config ARCH_HAS_PROTECTED_GUEST
+ bool
+
#
# ABI hall of shame
#
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index ff79263aebd1..d506aae29dd9 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -883,6 +883,7 @@ config INTEL_TDX_GUEST
select PARAVIRT_XL
select X86_X2APIC
select SECURITY_LOCKDOWN_LSM
+ select ARCH_HAS_PROTECTED_GUEST
help
Provide support for running in a trusted domain on Intel processors
equipped with Trusted Domain eXtenstions. TDX is a new Intel
@@ -1539,6 +1540,7 @@ 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/protected_guest.h b/arch/x86/include/asm/protected_guest.h
new file mode 100644
index 000000000000..d47668dee6c2
--- /dev/null
+++ b/arch/x86/include/asm/protected_guest.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Copyright (C) 2020 Intel Corporation */
+#ifndef _ASM_PROTECTED_GUEST_H
+#define _ASM_PROTECTED_GUEST_H 1
+
+#include <asm/processor.h>
+#include <asm/tdx.h>
+#include <asm/sev.h>
+
+static inline bool prot_guest_has(unsigned long flag)
+{
+ if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
+ return tdx_protected_guest_has(flag);
+ else if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
+ return sev_protected_guest_has(flag);
+
+ return false;
+}
+
+#endif /* _ASM_PROTECTED_GUEST_H */
diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index fa5cd05d3b5b..e9b0b93a3157 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -81,12 +81,15 @@ static __always_inline void sev_es_nmi_complete(void)
__sev_es_nmi_complete();
}
extern int __init sev_es_efi_map_ghcbs(pgd_t *pgd);
+bool sev_protected_guest_has(unsigned long flag);
+
#else
static inline void sev_es_ist_enter(struct pt_regs *regs) { }
static inline void sev_es_ist_exit(void) { }
static inline int sev_es_setup_ap_jump_table(struct real_mode_header *rmh) { return 0; }
static inline void sev_es_nmi_complete(void) { }
static inline int sev_es_efi_map_ghcbs(pgd_t *pgd) { return 0; }
+static inline bool sev_protected_guest_has(unsigned long flag) { return false; }
#endif

#endif
diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index c738bde944d1..1c17c9080a2c 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -11,10 +11,14 @@

void __init tdx_early_init(void);

+bool tdx_protected_guest_has(unsigned long flag);
+
#else

static inline void tdx_early_init(void) { };

+static inline bool tdx_protected_guest_has(unsigned long flag) { return false; }
+
#endif /* CONFIG_INTEL_TDX_GUEST */

#endif /* _ASM_X86_TDX_H */
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 651b81cd648e..3e88576555d2 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -19,6 +19,7 @@
#include <linux/memblock.h>
#include <linux/kernel.h>
#include <linux/mm.h>
+#include <linux/protected_guest.h>

#include <asm/cpu_entry_area.h>
#include <asm/stacktrace.h>
@@ -1493,3 +1494,19 @@ bool __init handle_vc_boot_ghcb(struct pt_regs *regs)
while (true)
halt();
}
+
+bool sev_protected_guest_has(unsigned long flag)
+{
+ switch (flag) {
+ case PR_GUEST_MEM_ENCRYPT:
+ case PR_GUEST_MEM_ENCRYPT_ACTIVE:
+ case PR_GUEST_UNROLL_STRING_IO:
+ case PR_GUEST_HOST_MEM_ENCRYPT:
+ return true;
+ case PR_GUEST_SEV:
+ return sev_active();
+ }
+
+ return false;
+}
+EXPORT_SYMBOL_GPL(sev_protected_guest_has);
diff --git a/arch/x86/kernel/tdx.c b/arch/x86/kernel/tdx.c
index b1492e076168..ae3334a2b29d 100644
--- a/arch/x86/kernel/tdx.c
+++ b/arch/x86/kernel/tdx.c
@@ -4,6 +4,8 @@
#undef pr_fmt
#define pr_fmt(fmt) "x86/tdx: " fmt

+#include <linux/protected_guest.h>
+
#include <asm/tdx.h>

static inline bool cpuid_has_tdx_guest(void)
@@ -18,6 +20,21 @@ static inline bool cpuid_has_tdx_guest(void)
return !memcmp("IntelTDX ", sig, 12);
}

+bool tdx_protected_guest_has(unsigned long flag)
+{
+ switch (flag) {
+ case PR_GUEST_MEM_ENCRYPT:
+ case PR_GUEST_MEM_ENCRYPT_ACTIVE:
+ case PR_GUEST_UNROLL_STRING_IO:
+ case PR_GUEST_SHARED_MAPPING_INIT:
+ case PR_GUEST_TDX:
+ return static_cpu_has(X86_FEATURE_TDX_GUEST);
+ }
+
+ return false;
+}
+EXPORT_SYMBOL_GPL(tdx_protected_guest_has);
+
void __init tdx_early_init(void)
{
if (!cpuid_has_tdx_guest())
diff --git a/include/linux/protected_guest.h b/include/linux/protected_guest.h
new file mode 100644
index 000000000000..c5b7547e5a68
--- /dev/null
+++ b/include/linux/protected_guest.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _LINUX_PROTECTED_GUEST_H
+#define _LINUX_PROTECTED_GUEST_H 1
+
+/* Protected Guest Feature Flags (leave 0-0xfff for vendor specific flags) */
+
+/* 0-ff is reserved for Intel specific flags */
+#define PR_GUEST_TDX 0x0000
+
+/* 100-1ff is reserved for AMD specific flags */
+#define PR_GUEST_SEV 0x0100
+
+/* Support for guest encryption */
+#define PR_GUEST_MEM_ENCRYPT 0x1000
+/* Encryption support is active */
+#define PR_GUEST_MEM_ENCRYPT_ACTIVE 0x1001
+/* Support for unrolled string IO */
+#define PR_GUEST_UNROLL_STRING_IO 0x1002
+/* Support for host memory encryption */
+#define PR_GUEST_HOST_MEM_ENCRYPT 0x1003
+/* Support for shared mapping initialization (after early init) */
+#define PR_GUEST_SHARED_MAPPING_INIT 0x1004
+
+#ifdef CONFIG_ARCH_HAS_PROTECTED_GUEST
+#include <asm/protected_guest.h>
+#else
+static inline bool prot_guest_has(unsigned long flag) { return false; }
+#endif
+
+#endif /* _LINUX_PROTECTED_GUEST_H */
--
2.25.1
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