diff --git a/OvmfPkg/Include/Library/MemEncryptSevLib.h b/OvmfPkg/Include/Library/MemEncryptSevLib.h
index 3c77d71df7..4fa9c0d700 100644
--- a/OvmfPkg/Include/Library/MemEncryptSevLib.h
+++ b/OvmfPkg/Include/Library/MemEncryptSevLib.h
@@ -214,4 +214,18 @@ MemEncryptSevClearMmioPageEncMask (
   IN UINTN             NumPages
   );
 
+/**
+  Pre-validate the system RAM when SEV-SNP is enabled in the guest VM.
+
+  @param[in]  BaseAddress             Base address
+  @param[in]  NumPages                Number of pages starting from the base address
+
+**/
+VOID
+EFIAPI
+MemEncryptSevSnpPreValidateSystemRam (
+  IN PHYSICAL_ADDRESS  BaseAddress,
+  IN UINTN             NumPages
+  );
+
 #endif // _MEM_ENCRYPT_SEV_LIB_H_
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/DxeMemEncryptSevLib.inf b/OvmfPkg/Library/BaseMemEncryptSevLib/DxeMemEncryptSevLib.inf
index f2e162d680..f613bb314f 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/DxeMemEncryptSevLib.inf
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/DxeMemEncryptSevLib.inf
@@ -34,8 +34,10 @@
   PeiDxeMemEncryptSevLibInternal.c
 
 [Sources.X64]
+  X64/DxeSnpSystemRamValidate.c
   X64/MemEncryptSevLib.c
   X64/PeiDxeVirtualMemory.c
+  X64/SnpPageStateChangeInternal.c
   X64/VirtualMemory.c
   X64/VirtualMemory.h
 
@@ -49,6 +51,7 @@
   DebugLib
   MemoryAllocationLib
   PcdLib
+  VmgExitLib
 
 [FeaturePcd]
   gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/Ia32/MemEncryptSevLib.c b/OvmfPkg/Library/BaseMemEncryptSevLib/Ia32/MemEncryptSevLib.c
index 9bd66301fc..f92299fc77 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/Ia32/MemEncryptSevLib.c
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/Ia32/MemEncryptSevLib.c
@@ -136,3 +136,20 @@ MemEncryptSevClearMmioPageEncMask (
   //
   return RETURN_UNSUPPORTED;
 }
+
+/**
+  Pre-validate the system RAM when SEV-SNP is enabled in the guest VM.
+
+  @param[in]  BaseAddress             Base address
+  @param[in]  NumPages                Number of pages starting from the base address
+
+**/
+VOID
+EFIAPI
+MemEncryptSevSnpPreValidateSystemRam (
+  IN PHYSICAL_ADDRESS  BaseAddress,
+  IN UINTN             NumPages
+  )
+{
+  ASSERT (FALSE);
+}
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf b/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf
index 03a78c32df..0402e49a10 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf
@@ -36,6 +36,8 @@
 [Sources.X64]
   X64/MemEncryptSevLib.c
   X64/PeiDxeVirtualMemory.c
+  X64/PeiSnpSystemRamValidate.c
+  X64/SnpPageStateChangeInternal.c
   X64/VirtualMemory.c
   X64/VirtualMemory.h
 
@@ -49,6 +51,7 @@
   DebugLib
   MemoryAllocationLib
   PcdLib
+  VmgExitLib
 
 [FeaturePcd]
   gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/SecMemEncryptSevLib.inf b/OvmfPkg/Library/BaseMemEncryptSevLib/SecMemEncryptSevLib.inf
index 279c38bfbc..939af0a91e 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/SecMemEncryptSevLib.inf
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/SecMemEncryptSevLib.inf
@@ -35,6 +35,8 @@
 [Sources.X64]
   X64/MemEncryptSevLib.c
   X64/SecVirtualMemory.c
+  X64/SecSnpSystemRamValidate.c
+  X64/SnpPageStateChangeInternal.c
   X64/VirtualMemory.c
   X64/VirtualMemory.h
 
@@ -46,6 +48,7 @@
   CpuLib
   DebugLib
   PcdLib
+  VmgExitLib
 
 [FixedPcd]
   gUefiCpuPkgTokenSpaceGuid.PcdSevEsWorkAreaBase
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/DxeSnpSystemRamValidate.c b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/DxeSnpSystemRamValidate.c
new file mode 100644
index 0000000000..d3a95e4913
--- /dev/null
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/DxeSnpSystemRamValidate.c
@@ -0,0 +1,40 @@
+/** @file
+
+  SEV-SNP Page Validation functions.
+
+  Copyright (c) 2021 AMD Incorporated. All rights reserved.<BR>
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include <Uefi/UefiBaseType.h>
+#include <Library/BaseLib.h>
+#include <Library/DebugLib.h>
+#include <Library/MemEncryptSevLib.h>
+
+#include "SnpPageStateChange.h"
+
+/**
+  Pre-validate the system RAM when SEV-SNP is enabled in the guest VM.
+
+  @param[in]  BaseAddress             Base address
+  @param[in]  NumPages                Number of pages starting from the base address
+
+**/
+VOID
+EFIAPI
+MemEncryptSevSnpPreValidateSystemRam (
+  IN PHYSICAL_ADDRESS  BaseAddress,
+  IN UINTN             NumPages
+  )
+{
+  if (!MemEncryptSevSnpIsEnabled ()) {
+    return;
+  }
+
+  //
+  // All the pre-validation must be completed in the PEI phase.
+  //
+  ASSERT (FALSE);
+}
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiSnpSystemRamValidate.c b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiSnpSystemRamValidate.c
new file mode 100644
index 0000000000..bc891c2636
--- /dev/null
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiSnpSystemRamValidate.c
@@ -0,0 +1,36 @@
+/** @file
+
+  SEV-SNP Page Validation functions.
+
+  Copyright (c) 2021 AMD Incorporated. All rights reserved.<BR>
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include <Uefi/UefiBaseType.h>
+#include <Library/BaseLib.h>
+#include <Library/MemEncryptSevLib.h>
+
+#include "SnpPageStateChange.h"
+
+/**
+  Pre-validate the system RAM when SEV-SNP is enabled in the guest VM.
+
+  @param[in]  BaseAddress             Base address
+  @param[in]  NumPages                Number of pages starting from the base address
+
+**/
+VOID
+EFIAPI
+MemEncryptSevSnpPreValidateSystemRam (
+  IN PHYSICAL_ADDRESS  BaseAddress,
+  IN UINTN             NumPages
+  )
+{
+  if (!MemEncryptSevSnpIsEnabled ()) {
+    return;
+  }
+
+  InternalSetPageState (BaseAddress, NumPages, SevSnpPagePrivate, TRUE);
+}
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SecSnpSystemRamValidate.c b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SecSnpSystemRamValidate.c
new file mode 100644
index 0000000000..bc891c2636
--- /dev/null
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SecSnpSystemRamValidate.c
@@ -0,0 +1,36 @@
+/** @file
+
+  SEV-SNP Page Validation functions.
+
+  Copyright (c) 2021 AMD Incorporated. All rights reserved.<BR>
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include <Uefi/UefiBaseType.h>
+#include <Library/BaseLib.h>
+#include <Library/MemEncryptSevLib.h>
+
+#include "SnpPageStateChange.h"
+
+/**
+  Pre-validate the system RAM when SEV-SNP is enabled in the guest VM.
+
+  @param[in]  BaseAddress             Base address
+  @param[in]  NumPages                Number of pages starting from the base address
+
+**/
+VOID
+EFIAPI
+MemEncryptSevSnpPreValidateSystemRam (
+  IN PHYSICAL_ADDRESS  BaseAddress,
+  IN UINTN             NumPages
+  )
+{
+  if (!MemEncryptSevSnpIsEnabled ()) {
+    return;
+  }
+
+  InternalSetPageState (BaseAddress, NumPages, SevSnpPagePrivate, TRUE);
+}
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChange.h b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChange.h
new file mode 100644
index 0000000000..b396f0ffbd
--- /dev/null
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChange.h
@@ -0,0 +1,30 @@
+/** @file
+
+  SEV-SNP Page Validation functions.
+
+  Copyright (c) 2021 AMD Incorporated. All rights reserved.<BR>
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#ifndef SNP_PAGE_STATE_INTERNAL_H_
+#define SNP_PAGE_STATE_INTERNAL_H_
+
+//
+// SEV-SNP Page states
+//
+typedef enum {
+  SevSnpPagePrivate,
+  SevSnpPageShared,
+} SEV_SNP_PAGE_STATE;
+
+VOID
+InternalSetPageState (
+  IN EFI_PHYSICAL_ADDRESS  BaseAddress,
+  IN UINTN                 NumPages,
+  IN SEV_SNP_PAGE_STATE    State,
+  IN BOOLEAN               UseLargeEntry
+  );
+
+#endif
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c
new file mode 100644
index 0000000000..9c552ef5c7
--- /dev/null
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c
@@ -0,0 +1,301 @@
+/** @file
+
+  SEV-SNP Page Validation functions.
+
+  Copyright (c) 2021 AMD Incorporated. All rights reserved.<BR>
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include <Uefi/UefiBaseType.h>
+#include <Library/BaseLib.h>
+#include <Library/BaseMemoryLib.h>
+#include <Library/MemEncryptSevLib.h>
+#include <Library/DebugLib.h>
+#include <Library/VmgExitLib.h>
+
+#include <Register/Amd/Ghcb.h>
+#include <Register/Amd/Msr.h>
+
+#include "SnpPageStateChange.h"
+
+#define IS_ALIGNED(x, y)  ((((x) & (y - 1)) == 0))
+#define PAGES_PER_LARGE_ENTRY  512
+
+STATIC
+UINTN
+MemoryStateToGhcbOp (
+  IN SEV_SNP_PAGE_STATE  State
+  )
+{
+  UINTN  Cmd;
+
+  switch (State) {
+    case SevSnpPageShared: Cmd = SNP_PAGE_STATE_SHARED;
+      break;
+    case SevSnpPagePrivate: Cmd = SNP_PAGE_STATE_PRIVATE;
+      break;
+    default: ASSERT (0);
+  }
+
+  return Cmd;
+}
+
+STATIC
+VOID
+SnpPageStateFailureTerminate (
+  VOID
+  )
+{
+  MSR_SEV_ES_GHCB_REGISTER  Msr;
+
+  //
+  // Use the GHCB MSR Protocol to request termination by the hypervisor
+  //
+  Msr.GhcbPhysicalAddress         = 0;
+  Msr.GhcbTerminate.Function      = GHCB_INFO_TERMINATE_REQUEST;
+  Msr.GhcbTerminate.ReasonCodeSet = GHCB_TERMINATE_GHCB;
+  Msr.GhcbTerminate.ReasonCode    = GHCB_TERMINATE_GHCB_GENERAL;
+  AsmWriteMsr64 (MSR_SEV_ES_GHCB, Msr.GhcbPhysicalAddress);
+
+  AsmVmgExit ();
+
+  ASSERT (FALSE);
+  CpuDeadLoop ();
+}
+
+/**
+ This function issues the PVALIDATE instruction to validate or invalidate the memory
+ range specified. If PVALIDATE returns size mismatch then it retry validating with
+ smaller page size.
+
+ */
+STATIC
+VOID
+PvalidateRange (
+  IN  SNP_PAGE_STATE_CHANGE_INFO  *Info,
+  IN  UINTN                       StartIndex,
+  IN  UINTN                       EndIndex,
+  IN  BOOLEAN                     Validate
+  )
+{
+  UINTN  Address, RmpPageSize, Ret, i;
+
+  for ( ; StartIndex <= EndIndex; StartIndex++) {
+    //
+    // Get the address and the page size from the Info.
+    //
+    Address     = Info->Entry[StartIndex].GuestFrameNumber << EFI_PAGE_SHIFT;
+    RmpPageSize = Info->Entry[StartIndex].PageSize;
+
+    Ret = AsmPvalidate (RmpPageSize, Validate, Address);
+
+    //
+    // If we fail to validate due to size mismatch then try with the
+    // smaller page size. This senario will occur if the backing page in
+    // the RMP entry is 4K and we are validating it as a 2MB.
+    //
+    if ((Ret == PVALIDATE_RET_SIZE_MISMATCH) && (RmpPageSize == PvalidatePageSize2MB)) {
+      for (i = 0; i < PAGES_PER_LARGE_ENTRY; i++) {
+        Ret = AsmPvalidate (PvalidatePageSize4K, Validate, Address);
+        if (Ret) {
+          break;
+        }
+
+        Address = Address + EFI_PAGE_SIZE;
+      }
+    }
+
+    //
+    // If validation failed then do not continue.
+    //
+    if (Ret) {
+      DEBUG ((
+        DEBUG_ERROR,
+        "%a:%a: Failed to %a address 0x%Lx Error code %d\n",
+        gEfiCallerBaseName,
+        __FUNCTION__,
+        Validate ? "Validate" : "Invalidate",
+        Address,
+        Ret
+        ));
+      SnpPageStateFailureTerminate ();
+    }
+  }
+}
+
+STATIC
+EFI_PHYSICAL_ADDRESS
+BuildPageStateBuffer (
+  IN EFI_PHYSICAL_ADDRESS        BaseAddress,
+  IN EFI_PHYSICAL_ADDRESS        EndAddress,
+  IN SEV_SNP_PAGE_STATE          State,
+  IN BOOLEAN                     UseLargeEntry,
+  IN SNP_PAGE_STATE_CHANGE_INFO  *Info
+  )
+{
+  EFI_PHYSICAL_ADDRESS  NextAddress;
+  UINTN                 i, RmpPageSize;
+
+  // Clear the page state structure
+  SetMem (Info, sizeof (*Info), 0);
+
+  i           = 0;
+  NextAddress = EndAddress;
+
+  //
+  // Populate the page state entry structure
+  //
+  while ((BaseAddress < EndAddress) && (i < SNP_PAGE_STATE_MAX_ENTRY)) {
+    //
+    // Is this a 2MB aligned page? Check if we can use the Large RMP entry.
+    //
+    if (UseLargeEntry && IS_ALIGNED (BaseAddress, SIZE_2MB) &&
+        ((EndAddress - BaseAddress) >= SIZE_2MB))
+    {
+      RmpPageSize = PvalidatePageSize2MB;
+      NextAddress = BaseAddress + SIZE_2MB;
+    } else {
+      RmpPageSize = PvalidatePageSize4K;
+      NextAddress = BaseAddress + EFI_PAGE_SIZE;
+    }
+
+    Info->Entry[i].GuestFrameNumber = BaseAddress >> EFI_PAGE_SHIFT;
+    Info->Entry[i].PageSize         = RmpPageSize;
+    Info->Entry[i].Operation        = MemoryStateToGhcbOp (State);
+    Info->Entry[i].CurrentPage      = 0;
+    Info->Header.EndEntry           = (UINT16)i;
+
+    BaseAddress = NextAddress;
+    i++;
+  }
+
+  return NextAddress;
+}
+
+STATIC
+VOID
+PageStateChangeVmgExit (
+  IN GHCB                        *Ghcb,
+  IN SNP_PAGE_STATE_CHANGE_INFO  *Info
+  )
+{
+  EFI_STATUS  Status;
+
+  //
+  // As per the GHCB specification, the hypervisor can resume the guest before
+  // processing all the entries. Checks whether all the entries are processed.
+  //
+  // The stragtegy here is to wait for the hypervisor to change the page
+  // state in the RMP table before guest access the memory pages. If the
+  // page state was not successful, then later memory access will result
+  // in the crash.
+  //
+  while (Info->Header.CurrentEntry <= Info->Header.EndEntry) {
+    Ghcb->SaveArea.SwScratch = (UINT64)Ghcb->SharedBuffer;
+    VmgSetOffsetValid (Ghcb, GhcbSwScratch);
+
+    Status = VmgExit (Ghcb, SVM_EXIT_SNP_PAGE_STATE_CHANGE, 0, 0);
+
+    //
+    // The Page State Change VMGEXIT can pass the failure through the
+    // ExitInfo2. Lets check both the return value as well as ExitInfo2.
+    //
+    if ((Status != 0) || (Ghcb->SaveArea.SwExitInfo2)) {
+      SnpPageStateFailureTerminate ();
+    }
+  }
+}
+
+/**
+ The function is used to set the page state when SEV-SNP is active. The page state
+ transition consist of changing the page ownership in the RMP table, and using the
+ PVALIDATE instruction to update the Validated bit in RMP table.
+
+ When the UseLargeEntry is set to TRUE, then function will try to use the large RMP
+ entry (whevever possible).
+ */
+VOID
+InternalSetPageState (
+  IN EFI_PHYSICAL_ADDRESS  BaseAddress,
+  IN UINTN                 NumPages,
+  IN SEV_SNP_PAGE_STATE    State,
+  IN BOOLEAN               UseLargeEntry
+  )
+{
+  GHCB                        *Ghcb;
+  EFI_PHYSICAL_ADDRESS        NextAddress, EndAddress;
+  MSR_SEV_ES_GHCB_REGISTER    Msr;
+  BOOLEAN                     InterruptState;
+  SNP_PAGE_STATE_CHANGE_INFO  *Info;
+
+  Msr.GhcbPhysicalAddress = AsmReadMsr64 (MSR_SEV_ES_GHCB);
+  Ghcb                    = Msr.Ghcb;
+
+  EndAddress = BaseAddress + EFI_PAGES_TO_SIZE (NumPages);
+
+  DEBUG ((
+    DEBUG_VERBOSE,
+    "%a:%a Address 0x%Lx - 0x%Lx State = %a LargeEntry = %d\n",
+    gEfiCallerBaseName,
+    __FUNCTION__,
+    BaseAddress,
+    EndAddress,
+    State == SevSnpPageShared ? "Shared" : "Private",
+    UseLargeEntry
+    ));
+
+  while (BaseAddress < EndAddress) {
+    UINTN  CurrentEntry, EndEntry;
+
+    //
+    // Initialize the GHCB
+    //
+    VmgInit (Ghcb, &InterruptState);
+
+    //
+    // Build the page state structure
+    //
+    Info        = (SNP_PAGE_STATE_CHANGE_INFO *)Ghcb->SharedBuffer;
+    NextAddress = BuildPageStateBuffer (
+                    BaseAddress,
+                    EndAddress,
+                    State,
+                    UseLargeEntry,
+                    Info
+                    );
+
+    //
+    // Save the current and end entry from the page state structure. We need
+    // it later.
+    //
+    CurrentEntry = Info->Header.CurrentEntry;
+    EndEntry     = Info->Header.EndEntry;
+
+    //
+    // If the caller requested to change the page state to shared then
+    // invalidate the pages before making the page shared in the RMP table.
+    //
+    if (State == SevSnpPageShared) {
+      PvalidateRange (Info, CurrentEntry, EndEntry, FALSE);
+    }
+
+    //
+    // Invoke the page state change VMGEXIT.
+    //
+    PageStateChangeVmgExit (Ghcb, Info);
+
+    //
+    // If the caller requested to change the page state to private then
+    // validate the pages after it has been added in the RMP table.
+    //
+    if (State == SevSnpPagePrivate) {
+      PvalidateRange (Info, CurrentEntry, EndEntry, TRUE);
+    }
+
+    VmgDone (Ghcb, InterruptState);
+
+    BaseAddress = NextAddress;
+  }
+}
diff --git a/OvmfPkg/OvmfPkgIa32.dsc b/OvmfPkg/OvmfPkgIa32.dsc
index 6a5be97c05..1dc069e424 100644
--- a/OvmfPkg/OvmfPkgIa32.dsc
+++ b/OvmfPkg/OvmfPkgIa32.dsc
@@ -266,6 +266,7 @@
 !else
   CpuExceptionHandlerLib|UefiCpuPkg/Library/CpuExceptionHandlerLib/SecPeiCpuExceptionHandlerLib.inf
 !endif
+  MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/SecMemEncryptSevLib.inf
 
 [LibraryClasses.common.PEI_CORE]
   HobLib|MdePkg/Library/PeiHobLib/PeiHobLib.inf
diff --git a/OvmfPkg/OvmfPkgIa32X64.dsc b/OvmfPkg/OvmfPkgIa32X64.dsc
index 13d9a1f111..a766457e6b 100644
--- a/OvmfPkg/OvmfPkgIa32X64.dsc
+++ b/OvmfPkg/OvmfPkgIa32X64.dsc
@@ -270,6 +270,7 @@
 !else
   CpuExceptionHandlerLib|UefiCpuPkg/Library/CpuExceptionHandlerLib/SecPeiCpuExceptionHandlerLib.inf
 !endif
+  MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/SecMemEncryptSevLib.inf
 
 [LibraryClasses.common.PEI_CORE]
   HobLib|MdePkg/Library/PeiHobLib/PeiHobLib.inf