2 files changed, 43 insertions, 0 deletions
diff --git a/MdePkg/Include/Library/BaseLib.h b/MdePkg/Include/Library/BaseLib.h
index a2cd134bea..2452c1d92e 100644
--- a/MdePkg/Include/Library/BaseLib.h
+++ b/MdePkg/Include/Library/BaseLib.h
@@ -4861,6 +4861,41 @@ AsmPvalidate (
   IN   BOOLEAN                 Validate,
   IN   PHYSICAL_ADDRESS        Address
   );
+
+//
+// RDX settings for RMPADJUST
+//
+#define RMPADJUST_VMPL_MAX               3
+#define RMPADJUST_VMPL_MASK              0xFF
+#define RMPADJUST_VMPL_SHIFT             0
+#define RMPADJUST_PERMISSION_MASK_MASK   0xFF
+#define RMPADJUST_PERMISSION_MASK_SHIFT  8
+#define RMPADJUST_VMSA_PAGE_BIT          BIT16
+
+/**
+  Adjusts the permissions of an SEV-SNP guest page.
+
+  Executes a RMPADJUST instruction with the register state specified by Rax,
+  Rcx, and Rdx. Returns Eax. This function is only available on X64.
+
+  The instruction is available only when CPUID Fn8000_001F_EAX[SNP]=1.
+
+  @param[in]  Rax   The value to load into RAX before executing the RMPADJUST
+                    instruction.
+  @param[in]  Rcx   The value to load into RCX before executing the RMPADJUST
+                    instruction.
+  @param[in]  Rdx   The value to load into RDX before executing the RMPADJUST
+                    instruction.
+
+  @return     Eax
+**/
+UINT32
+EFIAPI
+AsmRmpAdjust (
+  IN      UINT64                     Rax,
+  IN      UINT64                     Rcx,
+  IN      UINT64                     Rdx
+  );
 #endif
 
 
diff --git a/MdePkg/Include/X64/Nasm.inc b/MdePkg/Include/X64/Nasm.inc
index 528bb33856..cfb14edc94 100644
--- a/MdePkg/Include/X64/Nasm.inc
+++ b/MdePkg/Include/X64/Nasm.inc
@@ -41,6 +41,14 @@
     DB 0xF2, 0x0F, 0x01, 0xFF
 %endmacro
 
+;
+; Macro for the RMPADJUST instruction, defined in AMD APM volume 3.
+; NASM feature request URL: https://bugzilla.nasm.us/show_bug.cgi?id=3392754
+;
+%macro RMPADJUST       0
+    DB 0xF3, 0x0F, 0x01, 0xFE
+%endmacro
+
 ; NASM provides built-in macros STRUC and ENDSTRUC for structure definition.
 ; For example, to define a structure called mytype containing a longword,
 ; a word, a byte and a string of bytes, you might code