[PATCH v2 20/23] OvmfPkg/VirtioNetDxe: alloc RxBuf using AllocateSharedPages()

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

RxBuf is shared between guest and hypervisor, use AllocateSharedPages()
to allocate this memory region and map it with BusMasterCommonBuffer
operation so that it can be accessed by guest and hypervisor.

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        |  3 +
 OvmfPkg/VirtioNetDxe/Events.c           |  6 ++
 OvmfPkg/VirtioNetDxe/SnpInitialize.c    | 68 ++++++++++++++++----
 OvmfPkg/VirtioNetDxe/SnpSharedHelpers.c |  6 +-
 4 files changed, 69 insertions(+), 14 deletions(-)

diff --git a/OvmfPkg/VirtioNetDxe/VirtioNet.h b/OvmfPkg/VirtioNetDxe/VirtioNet.h
index 2964c946e26e..a4661bd5d2fe 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
@@ -85,6 +86,8 @@ typedef struct {
   VOID                        *RxRingMap;        // VirtioNetInitRing
   UINT8                       *RxBuf;            // VirtioNetInitRx
   UINT16                      RxLastUsed;        // VirtioNetInitRx
+  UINTN                       RxBufNoPages;      // VirtioNetInitRx
+  VOID                        *RxBufMap;         // VirtioNetInitRx
 
   VRING                       TxRing;            // VirtioNetInitRing
   VOID                        *TxRingMap;        // VirtioNetInitRing
diff --git a/OvmfPkg/VirtioNetDxe/Events.c b/OvmfPkg/VirtioNetDxe/Events.c
index e832d40f7be4..2f61da6aece4 100644
--- a/OvmfPkg/VirtioNetDxe/Events.c
+++ b/OvmfPkg/VirtioNetDxe/Events.c
@@ -95,4 +95,10 @@ VirtioNetExitBoot (
   //
   Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, Dev->TxRingMap);
   Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, Dev->RxRingMap);
+
+  //
+  // Unmap Rx buffer so that hypervisor can not get readable data after
+  // device is reset.
+  //
+  Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, Dev->RxBufMap);
 }
diff --git a/OvmfPkg/VirtioNetDxe/SnpInitialize.c b/OvmfPkg/VirtioNetDxe/SnpInitialize.c
index be2761d3d068..db2314446bbb 100644
--- a/OvmfPkg/VirtioNetDxe/SnpInitialize.c
+++ b/OvmfPkg/VirtioNetDxe/SnpInitialize.c
@@ -247,13 +247,16 @@ 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;
+  UINT8                 *RxPtr;
+  UINTN                 NumBytes;
+  EFI_PHYSICAL_ADDRESS  DeviceAddress;
+  UINT64                BufBaseShift;
 
   //
   // In VirtIo 1.0, the NumBuffers field is mandatory. In 0.9.5, it depends on
@@ -278,11 +281,37 @@ 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 SharedPages() to
+  // allocate this memory region and Map() it using BusMasterCommonBuffer
+  // operation so that it can be accessed equally by both guest and
+  // hypervisor.
+  //
+  NumBytes = RxAlwaysPending * RxBufSize;
+  Dev->RxBufNoPages = EFI_SIZE_TO_PAGES (NumBytes);
+  Status = Dev->VirtIo->AllocateSharedPages (
+                          Dev->VirtIo,
+                          Dev->RxBufNoPages,
+                          (VOID *) &Dev->RxBuf
+                          );
+  if (EFI_ERROR (Status)) {
+    return Status;
   }
 
+  Status = VirtioMapAllBytesInSharedBuffer (
+             Dev->VirtIo,
+             VirtioOperationBusMasterCommonBuffer,
+             Dev->RxBuf,
+             NumBytes,
+             &DeviceAddress,
+             &Dev->RxBufMap
+             );
+  if (EFI_ERROR (Status)) {
+    goto FreeSharedBuffer;
+  }
+
+  BufBaseShift = (UINT64) (UINTN)Dev->RxBuf - (UINT64) DeviceAddress;
+
   //
   // virtio-0.9.5, 2.4.2 Receiving Used Buffers From the Device
   //
@@ -304,6 +333,11 @@ VirtioNetInitRx (
   DescIdx = 0;
   RxPtr = Dev->RxBuf;
   for (PktIdx = 0; PktIdx < RxAlwaysPending; ++PktIdx) {
+    UINT64    Address;
+
+    Address = (UINTN) RxPtr;
+    Address += BufBaseShift;
+
     //
     // virtio-0.9.5, 2.4.1.2 Updating the Available Ring
     // invisible to the host until we update the Index Field
@@ -313,13 +347,13 @@ 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].Addr  = (UINTN) Address;
     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].Addr  = (UINTN) Address;
     Dev->RxRing.Desc[DescIdx].Len   = (UINT32) (RxBufSize - VirtioNetReqSize);
     Dev->RxRing.Desc[DescIdx].Flags = VRING_DESC_F_WRITE;
     RxPtr += Dev->RxRing.Desc[DescIdx++].Len;
@@ -343,10 +377,18 @@ 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->RxBufNoPages,
+                 (VOID *) Dev->RxBuf);
+  return Status;
 }
 
 
diff --git a/OvmfPkg/VirtioNetDxe/SnpSharedHelpers.c b/OvmfPkg/VirtioNetDxe/SnpSharedHelpers.c
index 9fedb72fdbd4..ec8e63ebdc32 100644
--- a/OvmfPkg/VirtioNetDxe/SnpSharedHelpers.c
+++ b/OvmfPkg/VirtioNetDxe/SnpSharedHelpers.c
@@ -39,7 +39,11 @@ VirtioNetShutdownRx (
   IN OUT VNET_DEV *Dev
   )
 {
-  FreePool (Dev->RxBuf);
+  Dev->VirtIo->FreeSharedPages (
+                 Dev->VirtIo,
+                 Dev->RxBufNoPages,
+                 (VOID *) Dev->RxBuf
+                 );
 }
 
 
-- 
2.7.4