[PATCH v3 16/23] OvmfPkg/VirtioNetDxe: alloc RxBuf using AllocateSharedPages()

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

RxBuf is shared between guest and hypervisor, use
VIRTIO_DEVICE_PROTOCOL.AllocateSharedPages() to allocate this memory
region and map it with BusMasterCommonBuffer operation so that it can be
accessed by both 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    | 76 ++++++++++++++++----
 OvmfPkg/VirtioNetDxe/SnpSharedHelpers.c |  7 +-
 4 files changed, 78 insertions(+), 14 deletions(-)

diff --git a/OvmfPkg/VirtioNetDxe/VirtioNet.h b/OvmfPkg/VirtioNetDxe/VirtioNet.h
index d80d441b50a4..7df51bd044f5 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;        // VirtioRingMap
   UINT8                       *RxBuf;            // VirtioNetInitRx
   UINT16                      RxLastUsed;        // VirtioNetInitRx
+  UINTN                       RxBufNoPages;      // VirtioNetInitRx
+  VOID                        *RxBufMap;         // VirtioMapSharedBuffer
 
   VRING                       TxRing;            // VirtioNetInitRing
   VOID                        *TxRingMap;        // VirtioRingMap
diff --git a/OvmfPkg/VirtioNetDxe/Events.c b/OvmfPkg/VirtioNetDxe/Events.c
index 6950c4d56df1..0586a82cdf09 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 will not be able 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 803a38bd4239..bdc3fd7ac6a2 100644
--- a/OvmfPkg/VirtioNetDxe/SnpInitialize.c
+++ b/OvmfPkg/VirtioNetDxe/SnpInitialize.c
@@ -249,13 +249,17 @@ 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  RxBufDeviceAddress;
+  UINT64                BufBaseShift;
+  VOID                  *RxBuffer;
 
   //
   // In VirtIo 1.0, the NumBuffers field is mandatory. In 0.9.5, it depends on
@@ -280,11 +284,41 @@ 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 with 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,
+                          &RxBuffer
+                          );
+  if (EFI_ERROR (Status)) {
+    Status = EFI_OUT_OF_RESOURCES;
+    return Status;
   }
 
+  Status = VirtioMapAllBytesInSharedBuffer (
+             Dev->VirtIo,
+             VirtioOperationBusMasterCommonBuffer,
+             RxBuffer,
+             NumBytes,
+             &RxBufDeviceAddress,
+             &Dev->RxBufMap
+             );
+  if (EFI_ERROR (Status)) {
+    Status = EFI_OUT_OF_RESOURCES;
+    goto FreeSharedBuffer;
+  }
+
+  Dev->RxBuf = RxBuffer;
+
+  BufBaseShift = (UINT64) (UINTN)Dev->RxBuf - (UINT64) RxBufDeviceAddress;
+
   //
   // virtio-0.9.5, 2.4.2 Receiving Used Buffers From the Device
   //
@@ -306,6 +340,11 @@ 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
@@ -315,13 +354,13 @@ 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  = 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  = Address;
     Dev->RxRing.Desc[DescIdx].Len   = (UINT32) (RxBufSize - VirtioNetReqSize);
     Dev->RxRing.Desc[DescIdx].Flags = VRING_DESC_F_WRITE;
     RxPtr += Dev->RxRing.Desc[DescIdx++].Len;
@@ -345,10 +384,21 @@ 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->RxBufNoPages,
+                 (VOID *) Dev->RxBuf
+                 );
+  return Status;
 }
 
 
diff --git a/OvmfPkg/VirtioNetDxe/SnpSharedHelpers.c b/OvmfPkg/VirtioNetDxe/SnpSharedHelpers.c
index 9fedb72fdbd4..4c9d9ece0790 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->RxBufNoPages,
+                 (VOID *) Dev->RxBuf
+                 );
 }
 
 
-- 
2.7.4