From 0eebb791b1b8e96be64e9cafb96e93500c0d6163 Mon Sep 17 00:00:00 2001
From: Laszlo Ersek <lersek@redhat.com>
Date: Mar 14 2016 11:50:13 +0000
Subject: OvmfPkg: VirtioNetDxe: adapt virtio-net packet header size to virtio-1.0


In virtio-0.9.5, the size of the virtio-net packet header depends on
whether the VIRTIO_NET_F_MRG_RXBUF feature is negotiated -- the
"num_buffers" field is only appended to the header if the feature is
negotiated.

Since we never negotiate this feature, VirtioNetDxe never allocates room
for the "num_buffers" field.

With virtio-1.0, the "num_buffers" field is always there (although it
doesn't carry useful information without VIRTIO_NET_F_MRG_RXBUF). Adapt
the buffers that depend on the virtio-net header size (otherwise we have
skewed / truncated packets).

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>

---

diff --git a/OvmfPkg/VirtioNetDxe/SnpInitialize.c b/OvmfPkg/VirtioNetDxe/SnpInitialize.c
index 38012a0..4942b59 100644
--- a/OvmfPkg/VirtioNetDxe/SnpInitialize.c
+++ b/OvmfPkg/VirtioNetDxe/SnpInitialize.c
@@ -138,6 +138,7 @@ VirtioNetInitTx (
   IN OUT VNET_DEV *Dev
   )
 {
+  UINTN TxSharedReqSize;
   UINTN PktIdx;
 
   Dev->TxMaxPending = (UINT16) MIN (Dev->TxRing.QueueSize / 2,
@@ -149,6 +150,14 @@ VirtioNetInitTx (
     return EFI_OUT_OF_RESOURCES;
   }
 
+  //
+  // In VirtIo 1.0, the NumBuffers field is mandatory. In 0.9.5, it depends on
+  // VIRTIO_NET_F_MRG_RXBUF, which we never negotiate.
+  //
+  TxSharedReqSize = (Dev->VirtIo->Revision < VIRTIO_SPEC_REVISION (1, 0, 0)) ?
+                    sizeof Dev->TxSharedReq.Legacy :
+                    sizeof Dev->TxSharedReq;
+
   for (PktIdx = 0; PktIdx < Dev->TxMaxPending; ++PktIdx) {
     UINT16 DescIdx;
 
@@ -160,7 +169,7 @@ VirtioNetInitTx (
     // (unmodified by the host) virtio-net request header.
     //
     Dev->TxRing.Desc[DescIdx].Addr  = (UINTN) &Dev->TxSharedReq;
-    Dev->TxRing.Desc[DescIdx].Len   = sizeof Dev->TxSharedReq;
+    Dev->TxRing.Desc[DescIdx].Len   = (UINT32) TxSharedReqSize;
     Dev->TxRing.Desc[DescIdx].Flags = VRING_DESC_F_NEXT;
     Dev->TxRing.Desc[DescIdx].Next  = (UINT16) (DescIdx + 1);
 
@@ -174,8 +183,13 @@ VirtioNetInitTx (
   //
   // virtio-0.9.5, Appendix C, Packet Transmission
   //
-  Dev->TxSharedReq.Flags   = 0;
-  Dev->TxSharedReq.GsoType = VIRTIO_NET_HDR_GSO_NONE;
+  Dev->TxSharedReq.Legacy.Flags   = 0;
+  Dev->TxSharedReq.Legacy.GsoType = VIRTIO_NET_HDR_GSO_NONE;
+
+  //
+  // For VirtIo 1.0 only -- the field exists, but it is unused
+  //
+  Dev->TxSharedReq.NumBuffers = 0;
 
   //
   // virtio-0.9.5, 2.4.2 Receiving Used Buffers From the Device
@@ -223,6 +237,7 @@ VirtioNetInitRx (
   )
 {
   EFI_STATUS Status;
+  UINTN      VirtioNetReqSize;
   UINTN      RxBufSize;
   UINT16     RxAlwaysPending;
   UINTN      PktIdx;
@@ -230,12 +245,20 @@ VirtioNetInitRx (
   UINT8      *RxPtr;
 
   //
+  // In VirtIo 1.0, the NumBuffers field is mandatory. In 0.9.5, it depends on
+  // VIRTIO_NET_F_MRG_RXBUF, which we never negotiate.
+  //
+  VirtioNetReqSize = (Dev->VirtIo->Revision < VIRTIO_SPEC_REVISION (1, 0, 0)) ?
+                     sizeof (VIRTIO_NET_REQ) :
+                     sizeof (VIRTIO_1_0_NET_REQ);
+
+  //
   // For each incoming packet we must supply two descriptors:
   // - the recipient for the virtio-net request header, plus
   // - the recipient for the network data (which consists of Ethernet header
   //   and Ethernet payload).
   //
-  RxBufSize = sizeof (VIRTIO_NET_REQ) +
+  RxBufSize = VirtioNetReqSize +
               (Dev->Snm.MediaHeaderSize + Dev->Snm.MaxPacketSize);
 
   //
@@ -280,14 +303,13 @@ VirtioNetInitRx (
     // virtio-0.9.5, 2.4.1.1 Placing Buffers into the Descriptor Table
     //
     Dev->RxRing.Desc[DescIdx].Addr  = (UINTN) RxPtr;
-    Dev->RxRing.Desc[DescIdx].Len   = sizeof (VIRTIO_NET_REQ);
+    Dev->RxRing.Desc[DescIdx].Len   = (UINT32) VirtioNetReqSize;
     Dev->RxRing.Desc[DescIdx].Flags = VRING_DESC_F_WRITE | VRING_DESC_F_NEXT;
     Dev->RxRing.Desc[DescIdx].Next  = (UINT16) (DescIdx + 1);
     RxPtr += Dev->RxRing.Desc[DescIdx++].Len;
 
     Dev->RxRing.Desc[DescIdx].Addr  = (UINTN) RxPtr;
-    Dev->RxRing.Desc[DescIdx].Len   = (UINT32) (RxBufSize -
-                                                sizeof (VIRTIO_NET_REQ));
+    Dev->RxRing.Desc[DescIdx].Len   = (UINT32) (RxBufSize - VirtioNetReqSize);
     Dev->RxRing.Desc[DescIdx].Flags = VRING_DESC_F_WRITE;
     RxPtr += Dev->RxRing.Desc[DescIdx++].Len;
   }
diff --git a/OvmfPkg/VirtioNetDxe/VirtioNet.h b/OvmfPkg/VirtioNetDxe/VirtioNet.h
index 2d3f3d8..7bd8790 100644
--- a/OvmfPkg/VirtioNetDxe/VirtioNet.h
+++ b/OvmfPkg/VirtioNetDxe/VirtioNet.h
@@ -17,7 +17,7 @@
 #ifndef _VIRTIO_NET_DXE_H_
 #define _VIRTIO_NET_DXE_H_
 
-#include <IndustryStandard/VirtioNet.h>
+#include <IndustryStandard/Virtio10Net.h>
 #include <Library/DebugLib.h>
 #include <Library/VirtioLib.h>
 #include <Protocol/ComponentName.h>
@@ -89,7 +89,7 @@ typedef struct {
   UINT16                      TxMaxPending;      // VirtioNetInitTx
   UINT16                      TxCurPending;      // VirtioNetInitTx
   UINT16                      *TxFreeStack;      // VirtioNetInitTx
-  VIRTIO_NET_REQ              TxSharedReq;       // VirtioNetInitTx
+  VIRTIO_1_0_NET_REQ          TxSharedReq;       // VirtioNetInitTx
   UINT16                      TxLastUsed;        // VirtioNetInitTx
 } VNET_DEV;