[PATCH v4 7/8] OvmfPkg/VirtioNetDxe: map caller-supplied Tx packet to device-address

[Brijesh Singh <brijesh.singh@amd.com>]

When device is behind the IOMMU, driver is require to pass the device
address of caller-supplied transmit buffer for the bus master operations.

The patch uses VirtioNetMapTxBuf() to map caller-supplied Tx packet to a
device-address and enqueue the device address in VRING for transfer and
perform the reverse mapping when transfer is completed so that we can
return the caller-supplied buffer.

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
 OvmfPkg/VirtioNetDxe/SnpGetStatus.c | 35 ++++++++++++++++----
 OvmfPkg/VirtioNetDxe/SnpTransmit.c  | 27 +++++++++++----
 2 files changed, 49 insertions(+), 13 deletions(-)

diff --git a/OvmfPkg/VirtioNetDxe/SnpGetStatus.c b/OvmfPkg/VirtioNetDxe/SnpGetStatus.c
index 694940ea1d97..9b1c352227b3 100644
--- a/OvmfPkg/VirtioNetDxe/SnpGetStatus.c
+++ b/OvmfPkg/VirtioNetDxe/SnpGetStatus.c
@@ -61,11 +61,12 @@ VirtioNetGetStatus (
   OUT VOID                       **TxBuf OPTIONAL
   )
 {
-  VNET_DEV   *Dev;
-  EFI_TPL    OldTpl;
-  EFI_STATUS Status;
-  UINT16     RxCurUsed;
-  UINT16     TxCurUsed;
+  VNET_DEV             *Dev;
+  EFI_TPL              OldTpl;
+  EFI_STATUS           Status;
+  UINT16               RxCurUsed;
+  UINT16               TxCurUsed;
+  EFI_PHYSICAL_ADDRESS DeviceAddress;
 
   if (This == NULL) {
     return EFI_INVALID_PARAMETER;
@@ -141,14 +142,34 @@ VirtioNetGetStatus (
       ASSERT (DescIdx < (UINT32) (2 * Dev->TxMaxPending - 1));
 
       //
-      // report buffer address to caller that has been enqueued by caller
+      // get the device address that has been enqueued for the caller's
+      // transmit buffer
       //
-      *TxBuf = (VOID *)(UINTN) Dev->TxRing.Desc[DescIdx + 1].Addr;
+      DeviceAddress = Dev->TxRing.Desc[DescIdx + 1].Addr;
 
       //
       // now this descriptor can be used again to enqueue a transmit buffer
       //
       Dev->TxFreeStack[--Dev->TxCurPending] = (UINT16) DescIdx;
+
+      //
+      // Unmap the device address and perform the reverse mapping to find the
+      // caller buffer address.
+      //
+      Status = VirtioNetUnmapTxBuf (
+                 Dev,
+                 TxBuf,
+                 DeviceAddress
+                 );
+      if (EFI_ERROR (Status)) {
+        //
+        // VirtioNetUnmapTxBuf should never fail, if we have reached here
+        // that means our internal state has been corrupted
+        //
+        ASSERT (FALSE);
+        Status = EFI_DEVICE_ERROR;
+        goto Exit;
+      }
     }
   }
 
diff --git a/OvmfPkg/VirtioNetDxe/SnpTransmit.c b/OvmfPkg/VirtioNetDxe/SnpTransmit.c
index 7ca40d5d0650..b39226e138b9 100644
--- a/OvmfPkg/VirtioNetDxe/SnpTransmit.c
+++ b/OvmfPkg/VirtioNetDxe/SnpTransmit.c
@@ -73,11 +73,12 @@ VirtioNetTransmit (
   IN UINT16                      *Protocol OPTIONAL
   )
 {
-  VNET_DEV   *Dev;
-  EFI_TPL    OldTpl;
-  EFI_STATUS Status;
-  UINT16     DescIdx;
-  UINT16     AvailIdx;
+  VNET_DEV              *Dev;
+  EFI_TPL               OldTpl;
+  EFI_STATUS            Status;
+  UINT16                DescIdx;
+  UINT16                AvailIdx;
+  EFI_PHYSICAL_ADDRESS  DeviceAddress;
 
   if (This == NULL || BufferSize == 0 || Buffer == NULL) {
     return EFI_INVALID_PARAMETER;
@@ -144,10 +145,24 @@ VirtioNetTransmit (
   }
 
   //
+  // Map the transmit buffer system physical address to device address.
+  //
+  Status = VirtioNetMapTxBuf (
+             Dev,
+             Buffer,
+             BufferSize,
+             &DeviceAddress
+             );
+  if (EFI_ERROR (Status)) {
+    Status = EFI_DEVICE_ERROR;
+    goto Exit;
+  }
+
+  //
   // virtio-0.9.5, 2.4.1 Supplying Buffers to The Device
   //
   DescIdx = Dev->TxFreeStack[Dev->TxCurPending++];
-  Dev->TxRing.Desc[DescIdx + 1].Addr  = (UINTN) Buffer;
+  Dev->TxRing.Desc[DescIdx + 1].Addr  = DeviceAddress;
   Dev->TxRing.Desc[DescIdx + 1].Len   = (UINT32) BufferSize;
 
   //
-- 
2.9.5