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>
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

2 files changed, 30 insertions, 8 deletions

diff --git a/OvmfPkg/VirtioNetDxe/SnpInitialize.c b/OvmfPkg/VirtioNetDxe/SnpInitialize.c
index 38012a0df8..430670a980 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.V0_9_5 :

+                    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.V0_9_5.Flags   = 0;

+  Dev->TxSharedReq.V0_9_5.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 2d3f3d87eb..710859bc61 100644
--- a/OvmfPkg/VirtioNetDxe/VirtioNet.h
+++ b/OvmfPkg/VirtioNetDxe/VirtioNet.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;