[PATCH v3 3/8] OvmfPkg/VirtioNetDxe: alloc RxBuf using AllocateSharedPages()

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

When device is behind the IOMMU, VirtioNetDxe is required to use the
device address in bus master operations. RxBuf is allocated using
AllocatePool() which returns the system physical address.

The patch uses VIRTIO_DEVICE_PROTOCOL.AllocateSharedPages() to allocate
the RxBuf and map with VirtioMapAllBytesInSharedBuffer() so that we can
obtain the device address for RxBuf.

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/VirtioNet.h        |  4 +
 OvmfPkg/VirtioNetDxe/SnpInitialize.c    | 78 +++++++++++++++-----
 OvmfPkg/VirtioNetDxe/SnpReceive.c       |  5 +-
 OvmfPkg/VirtioNetDxe/SnpSharedHelpers.c |  7 +-
 OvmfPkg/VirtioNetDxe/TechNotes.txt      |  2 +-
 5 files changed, 75 insertions(+), 21 deletions(-)

diff --git a/OvmfPkg/VirtioNetDxe/VirtioNet.h b/OvmfPkg/VirtioNetDxe/VirtioNet.h
index 6762fc9d1d6e..995593f4b236 100644
--- a/OvmfPkg/VirtioNetDxe/VirtioNet.h
+++ b/OvmfPkg/VirtioNetDxe/VirtioNet.h
@@ -4,6 +4,7 @@
   Protocol instances for virtio-net devices.
 
   Copyright (C) 2013, Red Hat, Inc.
+  Copyright (c) 2017, AMD Inc, All rights reserved.<BR>
 
   This program and the accompanying materials are licensed and made available
   under the terms and conditions of the BSD License which accompanies this
@@ -86,6 +87,9 @@ typedef struct {
                                                  // VirtioNetInitRing
   UINT8                       *RxBuf;            // VirtioNetInitRx
   UINT16                      RxLastUsed;        // VirtioNetInitRx
+  UINTN                       RxBufNrPages;      // VirtioNetInitRx
+  EFI_PHYSICAL_ADDRESS        RxBufDeviceBase;   // VirtioNetInitRx
+  VOID                        *RxBufMap;         // VirtioNetInitRx
 
   VRING                       TxRing;            // VirtioNetInitRing
   VOID                        *TxRingMap;        // VirtioRingMap and
diff --git a/OvmfPkg/VirtioNetDxe/SnpInitialize.c b/OvmfPkg/VirtioNetDxe/SnpInitialize.c
index 8eabdbff6f5e..b739875d4c01 100644
--- a/OvmfPkg/VirtioNetDxe/SnpInitialize.c
+++ b/OvmfPkg/VirtioNetDxe/SnpInitialize.c
@@ -242,8 +242,9 @@ VirtioNetInitTx (
   @param[in,out] Dev       The VNET_DEV driver instance about to enter the
                            EfiSimpleNetworkInitialized state.
 
-  @retval EFI_OUT_OF_RESOURCES  Failed to allocate RX destination area.
-  @return                       Status codes from VIRTIO_CFG_WRITE().
+  @return                       Status codes from VIRTIO_CFG_WRITE() or
+                                VIRTIO_DEVICE_PROTOCOL.AllocateSharedPages or
+                                VirtioMapAllBytesInSharedBuffer().
   @retval EFI_SUCCESS           RX setup successful. The device is live and may
                                 already be writing to the receive area.
 */
@@ -255,13 +256,15 @@ VirtioNetInitRx (
   IN OUT VNET_DEV *Dev
   )
 {
-  EFI_STATUS Status;
-  UINTN      VirtioNetReqSize;
-  UINTN      RxBufSize;
-  UINT16     RxAlwaysPending;
-  UINTN      PktIdx;
-  UINT16     DescIdx;
-  UINT8      *RxPtr;
+  EFI_STATUS            Status;
+  UINTN                 VirtioNetReqSize;
+  UINTN                 RxBufSize;
+  UINT16                RxAlwaysPending;
+  UINTN                 PktIdx;
+  UINT16                DescIdx;
+  UINTN                 NumBytes;
+  EFI_PHYSICAL_ADDRESS  RxBufDeviceAddress;
+  VOID                  *RxBuffer;
 
   //
   // In VirtIo 1.0, the NumBuffers field is mandatory. In 0.9.5, it depends on
@@ -286,11 +289,39 @@ VirtioNetInitRx (
   //
   RxAlwaysPending = (UINT16) MIN (Dev->RxRing.QueueSize / 2, VNET_MAX_PENDING);
 
-  Dev->RxBuf = AllocatePool (RxAlwaysPending * RxBufSize);
-  if (Dev->RxBuf == NULL) {
-    return EFI_OUT_OF_RESOURCES;
+  //
+  // The RxBuf is shared between guest and hypervisor, use
+  // AllocateSharedPages() to allocate this memory region and map it with
+  // BusMasterCommonBuffer so that it can be accessed by both guest and
+  // hypervisor.
+  //
+  NumBytes = RxAlwaysPending * RxBufSize;
+  Dev->RxBufNrPages = EFI_SIZE_TO_PAGES (NumBytes);
+  Status = Dev->VirtIo->AllocateSharedPages (
+                          Dev->VirtIo,
+                          Dev->RxBufNrPages,
+                          &RxBuffer
+                          );
+  if (EFI_ERROR (Status)) {
+    return Status;
   }
 
+  ZeroMem (RxBuffer, NumBytes);
+
+  Status = VirtioMapAllBytesInSharedBuffer (
+             Dev->VirtIo,
+             VirtioOperationBusMasterCommonBuffer,
+             RxBuffer,
+             NumBytes,
+             &Dev->RxBufDeviceBase,
+             &Dev->RxBufMap
+             );
+  if (EFI_ERROR (Status)) {
+    goto FreeSharedBuffer;
+  }
+
+  Dev->RxBuf = RxBuffer;
+
   //
   // virtio-0.9.5, 2.4.2 Receiving Used Buffers From the Device
   //
@@ -310,7 +341,7 @@ VirtioNetInitRx (
   // link each chain into (from) the available ring as well
   //
   DescIdx = 0;
-  RxPtr = Dev->RxBuf;
+  RxBufDeviceAddress = Dev->RxBufDeviceBase;
   for (PktIdx = 0; PktIdx < RxAlwaysPending; ++PktIdx) {
     //
     // virtio-0.9.5, 2.4.1.2 Updating the Available Ring
@@ -321,16 +352,16 @@ 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].Addr  = RxBufDeviceAddress;
     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;
+    RxBufDeviceAddress += Dev->RxRing.Desc[DescIdx++].Len;
 
-    Dev->RxRing.Desc[DescIdx].Addr  = (UINTN) RxPtr;
+    Dev->RxRing.Desc[DescIdx].Addr  = RxBufDeviceAddress;
     Dev->RxRing.Desc[DescIdx].Len   = (UINT32) (RxBufSize - VirtioNetReqSize);
     Dev->RxRing.Desc[DescIdx].Flags = VRING_DESC_F_WRITE;
-    RxPtr += Dev->RxRing.Desc[DescIdx++].Len;
+    RxBufDeviceAddress += Dev->RxRing.Desc[DescIdx++].Len;
   }
 
   //
@@ -351,10 +382,21 @@ VirtioNetInitRx (
   Status = Dev->VirtIo->SetQueueNotify (Dev->VirtIo, VIRTIO_NET_Q_RX);
   if (EFI_ERROR (Status)) {
     Dev->VirtIo->SetDeviceStatus (Dev->VirtIo, 0);
-    FreePool (Dev->RxBuf);
+    goto UnmapSharedBuffer;
   }
 
   return Status;
+
+UnmapSharedBuffer:
+  Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, Dev->RxBufMap);
+
+FreeSharedBuffer:
+  Dev->VirtIo->FreeSharedPages (
+                 Dev->VirtIo,
+                 Dev->RxBufNrPages,
+                 RxBuffer
+                 );
+  return Status;
 }
 
 
diff --git a/OvmfPkg/VirtioNetDxe/SnpReceive.c b/OvmfPkg/VirtioNetDxe/SnpReceive.c
index 99abd7ebe454..c42489636ea0 100644
--- a/OvmfPkg/VirtioNetDxe/SnpReceive.c
+++ b/OvmfPkg/VirtioNetDxe/SnpReceive.c
@@ -82,6 +82,7 @@ VirtioNetReceive (
   UINT8      *RxPtr;
   UINT16     AvailIdx;
   EFI_STATUS NotifyStatus;
+  UINTN      RxBufOffset;
 
   if (This == NULL || BufferSize == NULL || Buffer == NULL) {
     return EFI_INVALID_PARAMETER;
@@ -143,7 +144,9 @@ VirtioNetReceive (
     *HeaderSize = Dev->Snm.MediaHeaderSize;
   }
 
-  RxPtr = (UINT8 *)(UINTN) Dev->RxRing.Desc[DescIdx + 1].Addr;
+  RxBufOffset = (UINTN)(Dev->RxRing.Desc[DescIdx + 1].Addr -
+                        Dev->RxBufDeviceBase);
+  RxPtr = Dev->RxBuf + RxBufOffset;
   CopyMem (Buffer, RxPtr, RxLen);
 
   if (DestAddr != NULL) {
diff --git a/OvmfPkg/VirtioNetDxe/SnpSharedHelpers.c b/OvmfPkg/VirtioNetDxe/SnpSharedHelpers.c
index 57c7395848bd..ee4f9ed36ecd 100644
--- a/OvmfPkg/VirtioNetDxe/SnpSharedHelpers.c
+++ b/OvmfPkg/VirtioNetDxe/SnpSharedHelpers.c
@@ -39,7 +39,12 @@ VirtioNetShutdownRx (
   IN OUT VNET_DEV *Dev
   )
 {
-  FreePool (Dev->RxBuf);
+  Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, Dev->RxBufMap);
+  Dev->VirtIo->FreeSharedPages (
+                 Dev->VirtIo,
+                 Dev->RxBufNrPages,
+                 Dev->RxBuf
+                 );
 }
 
 
diff --git a/OvmfPkg/VirtioNetDxe/TechNotes.txt b/OvmfPkg/VirtioNetDxe/TechNotes.txt
index 37250b14a98c..fedbaee07ec7 100644
--- a/OvmfPkg/VirtioNetDxe/TechNotes.txt
+++ b/OvmfPkg/VirtioNetDxe/TechNotes.txt
@@ -247,7 +247,7 @@ In VirtioNetInitRx, the guest allocates the fixed size Receive Destination
 Area, which accommodates all packets delivered asynchronously by the host. To
 each packet, a slice of this area is dedicated; each slice is further
 subdivided into virtio-net request header and network packet data. The
-(guest-physical) addresses of these sub-slices are denoted with A2, A3, A4 and
+(device-physical) addresses of these sub-slices are denoted with A2, A3, A4 and
 so on. Importantly, an even-subscript "A" always belongs to a virtio-net
 request header, while an odd-subscript "A" always belongs to a packet
 sub-slice.
-- 
2.9.5