diff --git a/src/arch/riscv/core/riscv_dma.c b/src/arch/riscv/core/riscv_dma.c
index d215fba2c..ab88f2785 100644
--- a/src/arch/riscv/core/riscv_dma.c
+++ b/src/arch/riscv/core/riscv_dma.c
@@ -44,24 +44,57 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
  * @v flags		Mapping flags
  * @ret rc		Return status code
  */
-static int riscv_dma_map ( struct dma_device *dma __unused,
-			   struct dma_mapping *map __unused,
+static int riscv_dma_map ( struct dma_device *dma,
+			   struct dma_mapping *map,
 			   void *addr, size_t len, int flags ) {
 
 	/* Sanity check: we cannot support bidirectional mappings */
 	assert ( ! ( ( flags & DMA_TX ) & ( flags & DMA_RX ) ) );
 
+	/* Populate mapping */
+	map->dma = dma;
+	map->offset = 0;
+	map->token = NULL;
+
 	/* Flush cached data to transmit buffers */
 	if ( flags & DMA_TX )
 		cache_clean ( addr, len );
 
-	/* Invalidate cached data in receive buffers */
-	if ( flags & DMA_RX )
+	/* Invalidate cached data in receive buffers and record address */
+	if ( flags & DMA_RX ) {
 		cache_invalidate ( addr, len );
+		map->token = addr;
+	}
+
+	/* Increment mapping count (for debugging) */
+	if ( DBG_LOG )
+		dma->mapped++;
 
 	return 0;
 }
 
+/**
+ * Unmap buffer
+ *
+ * @v map		DMA mapping
+ * @v len		Used length
+ */
+static void riscv_dma_unmap ( struct dma_mapping *map, size_t len ) {
+	struct dma_device *dma = map->dma;
+	void *addr = map->token;
+
+	/* Invalidate cached data in receive buffers */
+	if ( addr )
+		cache_invalidate ( addr, len );
+
+	/* Clear mapping */
+	map->dma = NULL;
+
+	/* Decrement mapping count (for debugging) */
+	if ( DBG_LOG )
+		dma->mapped--;
+}
+
 /**
  * Allocate and map DMA-coherent buffer
  *
@@ -98,6 +131,10 @@ static void * riscv_dma_alloc ( struct dma_device *dma,
 	DBGC ( dma, "DMA allocated [%#08lx,%#08lx) via %p\n",
 	       phys, ( phys + len ), caddr );
 
+	/* Increment allocation count (for debugging) */
+	if ( DBG_LOG )
+		dma->allocated++;
+
 	return caddr;
 }
 
@@ -111,6 +148,7 @@ static void * riscv_dma_alloc ( struct dma_device *dma,
  */
 static void riscv_dma_free ( struct dma_mapping *map,
 			     void *addr, size_t len ) {
+	struct dma_device *dma = map->dma;
 
 	/* Sanity check */
 	assert ( virt_to_phys ( addr ) == virt_to_phys ( map->token ) );
@@ -121,10 +159,14 @@ static void riscv_dma_free ( struct dma_mapping *map,
 	/* Clear mapping */
 	map->dma = NULL;
 	map->token = NULL;
+
+	/* Decrement allocation count (for debugging) */
+	if ( DBG_LOG )
+		dma->allocated--;
 }
 
 PROVIDE_DMAAPI ( riscv, dma_map, riscv_dma_map );
-PROVIDE_DMAAPI_INLINE ( riscv, dma_unmap );
+PROVIDE_DMAAPI ( riscv, dma_unmap, riscv_dma_unmap );
 PROVIDE_DMAAPI ( riscv, dma_alloc, riscv_dma_alloc );
 PROVIDE_DMAAPI ( riscv, dma_free, riscv_dma_free );
 PROVIDE_DMAAPI ( riscv, dma_umalloc, riscv_dma_alloc );
diff --git a/src/arch/riscv/include/ipxe/riscv_dma.h b/src/arch/riscv/include/ipxe/riscv_dma.h
index 568f28afe..d35904d88 100644
--- a/src/arch/riscv/include/ipxe/riscv_dma.h
+++ b/src/arch/riscv/include/ipxe/riscv_dma.h
@@ -15,17 +15,6 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #define DMAAPI_PREFIX_riscv __riscv_
 #endif
 
-/**
- * Unmap buffer
- *
- * @v map		DMA mapping
- */
-static inline __always_inline void
-DMAAPI_INLINE ( riscv, dma_unmap ) ( struct dma_mapping *map __unused ) {
-
-	/* Nothing to do */
-}
-
 /**
  * Set addressable space mask
  *
diff --git a/src/core/dma.c b/src/core/dma.c
index cbc9b8d10..3f3023c4d 100644
--- a/src/core/dma.c
+++ b/src/core/dma.c
@@ -79,13 +79,14 @@ static int dma_op_map ( struct dma_device *dma, struct dma_mapping *map,
  * Unmap buffer
  *
  * @v map		DMA mapping
+ * @v len		Used length
  */
-static void dma_op_unmap ( struct dma_mapping *map ) {
+static void dma_op_unmap ( struct dma_mapping *map, size_t len ) {
 	struct dma_device *dma = map->dma;
 
 	assert ( dma != NULL );
 	assert ( dma->op != NULL );
-	dma->op->unmap ( dma, map );
+	dma->op->unmap ( dma, map, len );
 }
 
 /**
diff --git a/src/drivers/net/intelxl.c b/src/drivers/net/intelxl.c
index 1d4c22a09..31a3e2577 100644
--- a/src/drivers/net/intelxl.c
+++ b/src/drivers/net/intelxl.c
@@ -90,7 +90,7 @@ int intelxl_msix_enable ( struct intelxl_nic *intelxl,
 
 	pci_msix_disable ( pci, &intelxl->msix.cap );
  err_enable:
-	dma_unmap ( &intelxl->msix.map );
+	dma_unmap ( &intelxl->msix.map, sizeof ( intelxl->msix.msg ) );
  err_map:
 	return rc;
 }
@@ -112,7 +112,7 @@ void intelxl_msix_disable ( struct intelxl_nic *intelxl,
 	pci_msix_disable ( pci, &intelxl->msix.cap );
 
 	/* Unmap dummy target location */
-	dma_unmap ( &intelxl->msix.map );
+	dma_unmap ( &intelxl->msix.map, sizeof ( intelxl->msix.msg ) );
 }
 
 /******************************************************************************
diff --git a/src/include/ipxe/dma.h b/src/include/ipxe/dma.h
index b675df212..a6e41c1ab 100644
--- a/src/include/ipxe/dma.h
+++ b/src/include/ipxe/dma.h
@@ -74,8 +74,10 @@ struct dma_operations {
 	 *
 	 * @v dma		DMA device
 	 * @v map		DMA mapping
+	 * @v len		Used length
 	 */
-	void ( * unmap ) ( struct dma_device *dma, struct dma_mapping *map );
+	void ( * unmap ) ( struct dma_device *dma, struct dma_mapping *map,
+			   size_t len );
 	/**
 	 * Allocate and map DMA-coherent buffer
 	 *
@@ -194,9 +196,11 @@ DMAAPI_INLINE ( flat, dma_map ) ( struct dma_device *dma,
  * Unmap buffer
  *
  * @v map		DMA mapping
+ * @v len		Used length
  */
 static inline __always_inline void
-DMAAPI_INLINE ( flat, dma_unmap ) ( struct dma_mapping *map ) {
+DMAAPI_INLINE ( flat, dma_unmap ) ( struct dma_mapping *map,
+				    size_t len __unused ) {
 
 	/* Decrement mapping count (for debugging) */
 	if ( DBG_LOG ) {
@@ -365,8 +369,9 @@ int dma_map ( struct dma_device *dma, struct dma_mapping *map,
  * Unmap buffer
  *
  * @v map		DMA mapping
+ * @v len		Used length
  */
-void dma_unmap ( struct dma_mapping *map );
+void dma_unmap ( struct dma_mapping *map, size_t len );
 
 /**
  * Allocate and map DMA-coherent buffer
diff --git a/src/include/ipxe/iobuf.h b/src/include/ipxe/iobuf.h
index df8d0b854..46b350458 100644
--- a/src/include/ipxe/iobuf.h
+++ b/src/include/ipxe/iobuf.h
@@ -276,7 +276,7 @@ static inline __always_inline physaddr_t iob_dma ( struct io_buffer *iobuf ) {
  * @ret rc		Return status code
  */
 static inline __always_inline void iob_unmap ( struct io_buffer *iobuf ) {
-	dma_unmap ( &iobuf->map );
+	dma_unmap ( &iobuf->map, iob_len ( iobuf ) );
 }
 
 extern struct io_buffer * __malloc alloc_iob_raw ( size_t len, size_t align,
diff --git a/src/interface/efi/efi_pci.c b/src/interface/efi/efi_pci.c
index ae0ec4264..fbf06300b 100644
--- a/src/interface/efi/efi_pci.c
+++ b/src/interface/efi/efi_pci.c
@@ -537,9 +537,10 @@ static int efipci_dma_map ( struct dma_device *dma, struct dma_mapping *map,
  *
  * @v dma		DMA device
  * @v map		DMA mapping
+ * @v len		Used length
  */
 static void efipci_dma_unmap ( struct dma_device *dma,
-			       struct dma_mapping *map ) {
+			       struct dma_mapping *map, size_t len __unused ) {
 	struct efi_pci_device *efipci =
 		container_of ( dma, struct efi_pci_device, pci.dma );
 	EFI_PCI_IO_PROTOCOL *pci_io = efipci->io;
@@ -606,7 +607,7 @@ static void * efipci_dma_alloc ( struct dma_device *dma,
 
 	return addr;
 
-	efipci_dma_unmap ( dma, map );
+	efipci_dma_unmap ( dma, map, len );
  err_map:
 	pci_io->FreeBuffer ( pci_io, pages, addr );
  err_alloc:
@@ -632,7 +633,7 @@ static void efipci_dma_free ( struct dma_device *dma, struct dma_mapping *map,
 	pages = ( ( len + EFI_PAGE_SIZE - 1 ) / EFI_PAGE_SIZE );
 
 	/* Unmap buffer */
-	efipci_dma_unmap ( dma, map );
+	efipci_dma_unmap ( dma, map, len );
 
 	/* Free buffer */
 	pci_io->FreeBuffer ( pci_io, pages, addr );