From: Tom Lendacky thomas.lendacky@amd.com
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@amd.com Signed-off-by: Borislav Petkov bp@suse.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 ab83c22d274e..9f190ec4f953 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 9c80c68d75b5..3fb9f5ebefa4 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 8f4e8fa6ed75..2ff3e600f426 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 000000000000..03bb2f343ddb --- /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@amd.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 ff08dc463634..e29b1418d00c 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>