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Subject[PATCH v7 03/45] x86/mm: Extend cc_attr to include AMD SEV-SNP
Date
The CC_ATTR_SEV_SNP can be used by the guest to query whether the SNP -
Secure Nested Paging feature is active.

Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
arch/x86/include/asm/msr-index.h | 2 ++
arch/x86/kernel/cc_platform.c | 2 ++
arch/x86/mm/mem_encrypt.c | 4 ++++
include/linux/cc_platform.h | 8 ++++++++
4 files changed, 16 insertions(+)

diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 01e2650b9585..98a64b230447 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -481,8 +481,10 @@
#define MSR_AMD64_SEV 0xc0010131
#define MSR_AMD64_SEV_ENABLED_BIT 0
#define MSR_AMD64_SEV_ES_ENABLED_BIT 1
+#define MSR_AMD64_SEV_SNP_ENABLED_BIT 2
#define MSR_AMD64_SEV_ENABLED BIT_ULL(MSR_AMD64_SEV_ENABLED_BIT)
#define MSR_AMD64_SEV_ES_ENABLED BIT_ULL(MSR_AMD64_SEV_ES_ENABLED_BIT)
+#define MSR_AMD64_SEV_SNP_ENABLED BIT_ULL(MSR_AMD64_SEV_SNP_ENABLED_BIT)

#define MSR_AMD64_VIRT_SPEC_CTRL 0xc001011f

diff --git a/arch/x86/kernel/cc_platform.c b/arch/x86/kernel/cc_platform.c
index 03bb2f343ddb..e05310f5ec2f 100644
--- a/arch/x86/kernel/cc_platform.c
+++ b/arch/x86/kernel/cc_platform.c
@@ -50,6 +50,8 @@ static bool amd_cc_platform_has(enum cc_attr attr)
case CC_ATTR_GUEST_STATE_ENCRYPT:
return sev_status & MSR_AMD64_SEV_ES_ENABLED;

+ case CC_ATTR_SEV_SNP:
+ return sev_status & MSR_AMD64_SEV_SNP_ENABLED;
default:
return false;
}
diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
index 23d54b810f08..534c2c82fbec 100644
--- a/arch/x86/mm/mem_encrypt.c
+++ b/arch/x86/mm/mem_encrypt.c
@@ -433,6 +433,10 @@ static void print_mem_encrypt_feature_info(void)
if (cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT))
pr_cont(" SEV-ES");

+ /* Secure Nested Paging */
+ if (cc_platform_has(CC_ATTR_SEV_SNP))
+ pr_cont(" SEV-SNP");
+
pr_cont("\n");
}

diff --git a/include/linux/cc_platform.h b/include/linux/cc_platform.h
index a075b70b9a70..ef5e2209c9b8 100644
--- a/include/linux/cc_platform.h
+++ b/include/linux/cc_platform.h
@@ -61,6 +61,14 @@ enum cc_attr {
* Examples include SEV-ES.
*/
CC_ATTR_GUEST_STATE_ENCRYPT,
+
+ /**
+ * @CC_ATTR_SEV_SNP: Guest SNP is active.
+ *
+ * The platform/OS is running as a guest/virtual machine and actively
+ * using AMD SEV-SNP features.
+ */
+ CC_ATTR_SEV_SNP = 0x100,
};

#ifdef CONFIG_ARCH_HAS_CC_PLATFORM
--
2.25.1
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