diff --git a/OvmfPkg/VirtioNetDxe/SnpInitialize.c b/OvmfPkg/VirtioNetDxe/SnpInitialize.c
index 9621f936d2..ffb3deefe0 100644
--- a/OvmfPkg/VirtioNetDxe/SnpInitialize.c
+++ b/OvmfPkg/VirtioNetDxe/SnpInitialize.c
@@ -147,7 +147,8 @@ ReleaseQueue:
                            EfiSimpleNetworkInitialized state.
 
   @retval EFI_OUT_OF_RESOURCES  Failed to allocate the stack to track the heads
-                                of free descriptor chains.
+                                of free descriptor chains or failed to init
+                                TxBufCollection.
   @return                       Status codes from VIRTIO_DEVICE_PROTOCOL.
                                 AllocateSharedPages() or
                                 VirtioMapAllBytesInSharedBuffer()
@@ -176,6 +177,15 @@ VirtioNetInitTx (
     return EFI_OUT_OF_RESOURCES;
   }
 
+  Dev->TxBufCollection = OrderedCollectionInit (
+                           VirtioNetTxBufMapInfoCompare,
+                           VirtioNetTxBufDeviceAddressCompare
+                           );
+  if (Dev->TxBufCollection == NULL) {
+    Status = EFI_OUT_OF_RESOURCES;
+    goto FreeTxFreeStack;
+  }
+
   //
   // Allocate TxSharedReq header and map with BusMasterCommonBuffer so that it
   // can be accessed equally by both processor and device.
@@ -186,7 +196,7 @@ VirtioNetInitTx (
                           &TxSharedReqBuffer
                           );
   if (EFI_ERROR (Status)) {
-    goto FreeTxFreeStack;
+    goto UninitTxBufCollection;
   }
 
   ZeroMem (TxSharedReqBuffer, sizeof *Dev->TxSharedReq);
@@ -267,6 +277,10 @@ FreeTxSharedReqBuffer:
                  EFI_SIZE_TO_PAGES (sizeof *(Dev->TxSharedReq)),
                  TxSharedReqBuffer
                  );
+
+UninitTxBufCollection:
+  OrderedCollectionUninit (Dev->TxBufCollection);
+
 FreeTxFreeStack:
   FreePool (Dev->TxFreeStack);
 
diff --git a/OvmfPkg/VirtioNetDxe/SnpSharedHelpers.c b/OvmfPkg/VirtioNetDxe/SnpSharedHelpers.c
index 2fce8142d5..18dbf18125 100644
--- a/OvmfPkg/VirtioNetDxe/SnpSharedHelpers.c
+++ b/OvmfPkg/VirtioNetDxe/SnpSharedHelpers.c
@@ -18,6 +18,16 @@
 
 #include "VirtioNet.h"
 
+//
+// The user structure for the ordered collection that will track the mapping
+// info of the packets queued in TxRing
+//
+typedef struct {
+  VOID                  *Buffer;
+  EFI_PHYSICAL_ADDRESS  DeviceAddress;  // lookup key for reverse mapping
+  VOID                  *BufMap;
+} TX_BUF_MAP_INFO;
+
 /**
   Release RX and TX resources on the boundary of the
   EfiSimpleNetworkInitialized state.
@@ -54,6 +64,10 @@ VirtioNetShutdownTx (
   IN OUT VNET_DEV *Dev
   )
 {
+  ORDERED_COLLECTION_ENTRY *Entry, *Entry2;
+  TX_BUF_MAP_INFO          *TxBufMapInfo;
+  VOID                     *UserStruct;
+
   Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, Dev->TxSharedReqMap);
   Dev->VirtIo->FreeSharedPages (
                  Dev->VirtIo,
@@ -61,6 +75,17 @@ VirtioNetShutdownTx (
                  Dev->TxSharedReq
                  );
 
+  for (Entry = OrderedCollectionMin (Dev->TxBufCollection);
+       Entry != NULL;
+       Entry = Entry2) {
+    Entry2 = OrderedCollectionNext (Entry);
+    OrderedCollectionDelete (Dev->TxBufCollection, Entry, &UserStruct);
+    TxBufMapInfo = UserStruct;
+    Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, TxBufMapInfo->BufMap);
+    FreePool (TxBufMapInfo);
+  }
+  OrderedCollectionUninit (Dev->TxBufCollection);
+
   FreePool (Dev->TxFreeStack);
 }
 
@@ -83,3 +108,202 @@ VirtioNetUninitRing (
   Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, RingMap);
   VirtioRingUninit (Dev->VirtIo, Ring);
 }
+
+
+/**
+  Map Caller-supplied TxBuf buffer to the device-mapped address
+
+  @param[in]    Dev               The VNET_DEV driver instance which wants to
+                                  map the Tx packet.
+  @param[in]    Buffer            The system physical address of TxBuf
+  @param[in]    NumberOfBytes     Number of bytes to map
+  @param[out]   DeviceAddress     The resulting device address for the bus
+                                  master access.
+
+  @retval EFI_OUT_OF_RESOURCES    The request could not be completed due to
+                                  a lack of resources.
+  @return                         Status codes from
+                                  VirtioMapAllBytesInSharedBuffer()
+  @retval EFI_SUCCESS             Caller-supplied buffer is succesfully mapped.
+*/
+EFI_STATUS
+EFIAPI
+VirtioNetMapTxBuf (
+  IN  VNET_DEV              *Dev,
+  IN  VOID                  *Buffer,
+  IN  UINTN                 NumberOfBytes,
+  OUT EFI_PHYSICAL_ADDRESS  *DeviceAddress
+  )
+{
+  EFI_STATUS                Status;
+  TX_BUF_MAP_INFO           *TxBufMapInfo;
+  EFI_PHYSICAL_ADDRESS      Address;
+  VOID                      *Mapping;
+
+  TxBufMapInfo = AllocatePool (sizeof (*TxBufMapInfo));
+  if (TxBufMapInfo == NULL) {
+    return EFI_OUT_OF_RESOURCES;
+  }
+
+  Status = VirtioMapAllBytesInSharedBuffer (
+             Dev->VirtIo,
+             VirtioOperationBusMasterRead,
+             Buffer,
+             NumberOfBytes,
+             &Address,
+             &Mapping
+            );
+  if (EFI_ERROR (Status)) {
+    goto FreeTxBufMapInfo;
+  }
+
+  TxBufMapInfo->Buffer = Buffer;
+  TxBufMapInfo->DeviceAddress = Address;
+  TxBufMapInfo->BufMap = Mapping;
+
+  Status = OrderedCollectionInsert (
+             Dev->TxBufCollection,
+             NULL,
+             TxBufMapInfo
+             );
+  switch (Status) {
+  case EFI_OUT_OF_RESOURCES:
+    goto UnmapTxBuf;
+  case EFI_ALREADY_STARTED:
+    //
+    // This should never happen: it implies
+    //
+    // - an identity-mapping VIRTIO_DEVICE_PROTOCOL.MapSharedBuffer()
+    //   implementation -- which is fine,
+    //
+    // - and an SNP client that queues multiple instances of the exact same
+    //   buffer address with SNP.Transmit() -- which is undefined behavior,
+    //   based on the TxBuf language in UEFI-2.7,
+    //   EFI_SIMPLE_NETWORK.GetStatus().
+    //
+    ASSERT (FALSE);
+    Status = EFI_INVALID_PARAMETER;
+    goto UnmapTxBuf;
+  default:
+    ASSERT_EFI_ERROR (Status);
+    break;
+  }
+
+  *DeviceAddress = Address;
+  return EFI_SUCCESS;
+
+UnmapTxBuf:
+  Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, Mapping);
+
+FreeTxBufMapInfo:
+  FreePool (TxBufMapInfo);
+  return Status;
+}
+
+/**
+  Unmap (aka reverse mapping) device mapped TxBuf buffer to the system
+  physical address
+
+  @param[in]    Dev               The VNET_DEV driver instance which wants to
+                                  reverse- and unmap the Tx packet.
+  @param[out]   Buffer            The system physical address of TxBuf
+  @param[in]    DeviceAddress     The device address for the TxBuf
+
+  @retval EFI_INVALID_PARAMETER   The DeviceAddress is not mapped
+  @retval EFI_SUCCESS             The TxBuf at DeviceAddress has been unmapped,
+                                  and Buffer has been set to TxBuf's system
+                                  physical address.
+
+*/
+EFI_STATUS
+EFIAPI
+VirtioNetUnmapTxBuf (
+  IN  VNET_DEV              *Dev,
+  OUT VOID                  **Buffer,
+  IN  EFI_PHYSICAL_ADDRESS  DeviceAddress
+  )
+{
+  ORDERED_COLLECTION_ENTRY  *Entry;
+  TX_BUF_MAP_INFO           *TxBufMapInfo;
+  VOID                      *UserStruct;
+
+  Entry = OrderedCollectionFind (Dev->TxBufCollection, &DeviceAddress);
+  if (Entry == NULL) {
+    return EFI_INVALID_PARAMETER;
+  }
+
+  OrderedCollectionDelete (Dev->TxBufCollection, Entry, &UserStruct);
+
+  TxBufMapInfo = UserStruct;
+
+  *Buffer = TxBufMapInfo->Buffer;
+  Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, TxBufMapInfo->BufMap);
+  FreePool (TxBufMapInfo);
+
+  return EFI_SUCCESS;
+}
+
+/**
+  Comparator function for two TX_BUF_MAP_INFO objects.
+
+  @param[in] UserStruct1  Pointer to the first TX_BUF_MAP_INFO object.
+
+  @param[in] UserStruct2  Pointer to the second TX_BUF_MAP_INFO object.
+
+  @retval <0  If UserStruct1 compares less than UserStruct2.
+
+  @retval  0  If UserStruct1 compares equal to UserStruct2.
+
+  @retval >0  If UserStruct1 compares greater than UserStruct2.
+*/
+INTN
+EFIAPI
+VirtioNetTxBufMapInfoCompare (
+  IN CONST VOID *UserStruct1,
+  IN CONST VOID *UserStruct2
+  )
+{
+  CONST TX_BUF_MAP_INFO *MapInfo1;
+  CONST TX_BUF_MAP_INFO *MapInfo2;
+
+  MapInfo1 = UserStruct1;
+  MapInfo2 = UserStruct2;
+
+  return MapInfo1->DeviceAddress < MapInfo2->DeviceAddress ? -1 :
+         MapInfo1->DeviceAddress > MapInfo2->DeviceAddress ?  1 :
+         0;
+}
+
+/**
+  Compare a standalone DeviceAddress against a TX_BUF_MAP_INFO object
+  containing an embedded DeviceAddress.
+
+  @param[in] StandaloneKey  Pointer to DeviceAddress, which has type
+                            EFI_PHYSICAL_ADDRESS.
+
+  @param[in] UserStruct     Pointer to the TX_BUF_MAP_INFO object with the
+                            embedded DeviceAddress.
+
+  @retval <0  If StandaloneKey compares less than UserStruct's key.
+
+  @retval  0  If StandaloneKey compares equal to UserStruct's key.
+
+  @retval >0  If StandaloneKey compares greater than UserStruct's key.
+**/
+INTN
+EFIAPI
+VirtioNetTxBufDeviceAddressCompare (
+  IN CONST VOID *StandaloneKey,
+  IN CONST VOID *UserStruct
+  )
+{
+  CONST EFI_PHYSICAL_ADDRESS *DeviceAddress;
+  CONST TX_BUF_MAP_INFO      *MapInfo;
+
+  DeviceAddress = StandaloneKey;
+  MapInfo = UserStruct;
+
+  return *DeviceAddress < MapInfo->DeviceAddress ? -1 :
+         *DeviceAddress > MapInfo->DeviceAddress ?  1 :
+         0;
+}
diff --git a/OvmfPkg/VirtioNetDxe/VirtioNet.h b/OvmfPkg/VirtioNetDxe/VirtioNet.h
index 027f75993e..3fc88cfb79 100644
--- a/OvmfPkg/VirtioNetDxe/VirtioNet.h
+++ b/OvmfPkg/VirtioNetDxe/VirtioNet.h
@@ -26,6 +26,7 @@
 #include <Protocol/DevicePath.h>
 #include <Protocol/DriverBinding.h>
 #include <Protocol/SimpleNetwork.h>
+#include <Library/OrderedCollectionLib.h>
 
 #define VNET_SIG SIGNATURE_32 ('V', 'N', 'E', 'T')
 
@@ -100,6 +101,7 @@ typedef struct {
   VIRTIO_1_0_NET_REQ          *TxSharedReq;      // VirtioNetInitTx
   VOID                        *TxSharedReqMap;   // VirtioNetInitTx
   UINT16                      TxLastUsed;        // VirtioNetInitTx
+  ORDERED_COLLECTION          *TxBufCollection;  // VirtioNetInitTx
 } VNET_DEV;
 
 
@@ -280,6 +282,42 @@ VirtioNetUninitRing (
   IN     VOID     *RingMap
   );
 
+//
+// utility functions to map caller-supplied Tx buffer system physical address
+// to a device address and vice versa
+//
+EFI_STATUS
+EFIAPI
+VirtioNetMapTxBuf (
+  IN  VNET_DEV              *Dev,
+  IN  VOID                  *Buffer,
+  IN  UINTN                 NumberOfBytes,
+  OUT EFI_PHYSICAL_ADDRESS  *DeviceAddress
+  );
+
+EFI_STATUS
+EFIAPI
+VirtioNetUnmapTxBuf (
+  IN  VNET_DEV              *Dev,
+  OUT VOID                  **Buffer,
+  IN  EFI_PHYSICAL_ADDRESS  DeviceAddress
+  );
+
+INTN
+EFIAPI
+VirtioNetTxBufMapInfoCompare (
+  IN CONST VOID *UserStruct1,
+  IN CONST VOID *UserStruct2
+  );
+
+INTN
+EFIAPI
+VirtioNetTxBufDeviceAddressCompare (
+  IN CONST VOID *StandaloneKey,
+  IN CONST VOID *UserStruct
+  );
+
+
 //
 // event callbacks
 //
diff --git a/OvmfPkg/VirtioNetDxe/VirtioNet.inf b/OvmfPkg/VirtioNetDxe/VirtioNet.inf
index a855ad4ac1..9ff6d87e61 100644
--- a/OvmfPkg/VirtioNetDxe/VirtioNet.inf
+++ b/OvmfPkg/VirtioNetDxe/VirtioNet.inf
@@ -49,6 +49,7 @@
   DebugLib
   DevicePathLib
   MemoryAllocationLib
+  OrderedCollectionLib
   UefiBootServicesTableLib
   UefiDriverEntryPoint
   UefiLib