Add SecureTSC support

arch/x86/Kconfig

@@ -1552,6 +1552,7 @@ config AMD_MEM_ENCRYPT
 	select ARCH_HAS_CC_PLATFORM
 	select X86_MEM_ENCRYPT
 	select UNACCEPTED_MEMORY
+	select CRYPTO_LIB_AESGCM
 	help
 	  Say yes to enable support for the encryption of system memory.
 	  This requires an AMD processor that supports Secure Memory

arch/x86/boot/compressed/sev.c

@@ -401,7 +401,8 @@ void do_boot_stage2_vc(struct pt_regs *regs, unsigned long exit_code)
  * by the guest kernel. As and when a new feature is implemented in the
  * guest kernel, a corresponding bit should be added to the mask.
  */
-#define SNP_FEATURES_PRESENT	MSR_AMD64_SNP_DEBUG_SWAP
+#define SNP_FEATURES_PRESENT	(MSR_AMD64_SNP_DEBUG_SWAP |	\
+				 MSR_AMD64_SNP_SECURE_TSC)
 
 u64 snp_get_unsupported_features(u64 status)
 {

arch/x86/coco/core.c

@@ -65,7 +65,6 @@ static __maybe_unused __always_inline bool amd_cc_platform_vtom(enum cc_attr att
  * up under SME the trampoline area cannot be encrypted, whereas under SEV
  * the trampoline area must be encrypted.
  */
-
 static bool noinstr amd_cc_platform_has(enum cc_attr attr)
 {
 #ifdef CONFIG_AMD_MEM_ENCRYPT
@@ -97,6 +96,9 @@ static bool noinstr amd_cc_platform_has(enum cc_attr attr)
 	case CC_ATTR_GUEST_SEV_SNP:
 		return sev_status & MSR_AMD64_SEV_SNP_ENABLED;
 
+	case CC_ATTR_GUEST_SNP_SECURE_TSC:
+		return sev_status & MSR_AMD64_SNP_SECURE_TSC;
+
 	case CC_ATTR_HOST_SEV_SNP:
 		return cc_flags.host_sev_snp;