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Message-ID: <163334768930.25758.17620474558044432963.tip-bot2@tip-bot2>
Date: Mon, 04 Oct 2021 11:41:29 -0000
From: "tip-bot2 for Tom Lendacky" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Tom Lendacky <thomas.lendacky@....com>,
Borislav Petkov <bp@...e.de>, x86@...nel.org,
linux-kernel@...r.kernel.org
Subject: [tip: x86/cc] x86/sev: Add an x86 version of cc_platform_has()
The following commit has been merged into the x86/cc branch of tip:
Commit-ID: aa5a461171f98fde0df78c4f6b5018a1e967cf81
Gitweb: https://git.kernel.org/tip/aa5a461171f98fde0df78c4f6b5018a1e967cf81
Author: Tom Lendacky <thomas.lendacky@....com>
AuthorDate: Wed, 08 Sep 2021 17:58:34 -05:00
Committer: Borislav Petkov <bp@...e.de>
CommitterDate: Mon, 04 Oct 2021 11:46:20 +02:00
x86/sev: Add an x86 version of cc_platform_has()
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.
Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Link: https://lkml.kernel.org/r/20210928191009.32551-4-bp@alien8.de
---
arch/x86/Kconfig | 1 +-
arch/x86/include/asm/mem_encrypt.h | 1 +-
arch/x86/kernel/Makefile | 6 +++-
arch/x86/kernel/cc_platform.c | 69 +++++++++++++++++++++++++++++-
arch/x86/mm/mem_encrypt.c | 1 +-
5 files changed, 78 insertions(+)
create mode 100644 arch/x86/kernel/cc_platform.c
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index ab83c22..9f190ec 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1518,6 +1518,7 @@ 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 9c80c68..3fb9f5e 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>
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 8f4e8fa..2ff3e60 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -21,6 +21,7 @@ CFLAGS_REMOVE_ftrace.o = -pg
CFLAGS_REMOVE_early_printk.o = -pg
CFLAGS_REMOVE_head64.o = -pg
CFLAGS_REMOVE_sev.o = -pg
+CFLAGS_REMOVE_cc_platform.o = -pg
endif
KASAN_SANITIZE_head$(BITS).o := n
@@ -29,6 +30,7 @@ KASAN_SANITIZE_dumpstack_$(BITS).o := n
KASAN_SANITIZE_stacktrace.o := n
KASAN_SANITIZE_paravirt.o := n
KASAN_SANITIZE_sev.o := n
+KASAN_SANITIZE_cc_platform.o := n
# With some compiler versions the generated code results in boot hangs, caused
# by several compilation units. To be safe, disable all instrumentation.
@@ -47,6 +49,7 @@ endif
KCOV_INSTRUMENT := n
CFLAGS_head$(BITS).o += -fno-stack-protector
+CFLAGS_cc_platform.o += -fno-stack-protector
CFLAGS_irq.o := -I $(srctree)/$(src)/../include/asm/trace
@@ -147,6 +150,9 @@ 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 0000000..03bb2f3
--- /dev/null
+++ b/arch/x86/kernel/cc_platform.c
@@ -0,0 +1,69 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Confidential Computing Platform Capability checks
+ *
+ * Copyright (C) 2021 Advanced Micro Devices, Inc.
+ *
+ * Author: Tom Lendacky <thomas.lendacky@....com>
+ */
+
+#include <linux/export.h>
+#include <linux/cc_platform.h>
+#include <linux/mem_encrypt.h>
+
+#include <asm/processor.h>
+
+static bool __maybe_unused intel_cc_platform_has(enum cc_attr attr)
+{
+#ifdef CONFIG_INTEL_TDX_GUEST
+ return false;
+#else
+ return false;
+#endif
+}
+
+/*
+ * SME and SEV are very similar but they are not the same, so there are
+ * times that the kernel will need to distinguish between SME and SEV. The
+ * cc_platform_has() function is used for this. When a distinction isn't
+ * needed, the CC_ATTR_MEM_ENCRYPT attribute can be used.
+ *
+ * The trampoline code is a good example for this requirement. Before
+ * paging is activated, SME will access all memory as decrypted, but SEV
+ * will access all memory as encrypted. So, when APs are being brought
+ * up under SME the trampoline area cannot be encrypted, whereas under SEV
+ * the trampoline area must be encrypted.
+ */
+static bool amd_cc_platform_has(enum cc_attr attr)
+{
+#ifdef CONFIG_AMD_MEM_ENCRYPT
+ switch (attr) {
+ case CC_ATTR_MEM_ENCRYPT:
+ return sme_me_mask;
+
+ case CC_ATTR_HOST_MEM_ENCRYPT:
+ return sme_me_mask && !(sev_status & MSR_AMD64_SEV_ENABLED);
+
+ case CC_ATTR_GUEST_MEM_ENCRYPT:
+ return sev_status & MSR_AMD64_SEV_ENABLED;
+
+ case CC_ATTR_GUEST_STATE_ENCRYPT:
+ return sev_status & MSR_AMD64_SEV_ES_ENABLED;
+
+ default:
+ return false;
+ }
+#else
+ return false;
+#endif
+}
+
+
+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 ff08dc4..e29b141 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>
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