The Tx and Rx rings are accessed by both guest and hypervisor, allocate
the rings using newly added VirtIo->AllocateSharedPages() and map it with
BusMasterCommonBuffer 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     |  2 ++
 OvmfPkg/VirtioNetDxe/Events.c        |  7 +++++
 OvmfPkg/VirtioNetDxe/SnpInitialize.c | 28 +++++++++++++++-----
 3 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/OvmfPkg/VirtioNetDxe/VirtioNet.h b/OvmfPkg/VirtioNetDxe/VirtioNet.h
index 710859bc6115..2964c946e26e 100644
--- a/OvmfPkg/VirtioNetDxe/VirtioNet.h
+++ b/OvmfPkg/VirtioNetDxe/VirtioNet.h
@@ -82,10 +82,12 @@ typedef struct {
   EFI_HANDLE                  MacHandle;         // VirtioNetDriverBindingStart
 
   VRING                       RxRing;            // VirtioNetInitRing
+  VOID                        *RxRingMap;        // VirtioNetInitRing
   UINT8                       *RxBuf;            // VirtioNetInitRx
   UINT16                      RxLastUsed;        // VirtioNetInitRx
 
   VRING                       TxRing;            // VirtioNetInitRing
+  VOID                        *TxRingMap;        // VirtioNetInitRing
   UINT16                      TxMaxPending;      // VirtioNetInitTx
   UINT16                      TxCurPending;      // VirtioNetInitTx
   UINT16                      *TxFreeStack;      // VirtioNetInitTx
diff --git a/OvmfPkg/VirtioNetDxe/Events.c b/OvmfPkg/VirtioNetDxe/Events.c
index 5be1af6ffbee..e832d40f7be4 100644
--- a/OvmfPkg/VirtioNetDxe/Events.c
+++ b/OvmfPkg/VirtioNetDxe/Events.c
@@ -88,4 +88,11 @@ VirtioNetExitBoot (
   if (Dev->Snm.State == EfiSimpleNetworkInitialized) {
     Dev->VirtIo->SetDeviceStatus (Dev->VirtIo, 0);
   }
+
+  //
+  // Unmap Tx and Rx rings so that hypervisor can not get readable data
+  // after device is reset.
+  //
+  Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, Dev->TxRingMap);
+  Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, Dev->RxRingMap);
 }
diff --git a/OvmfPkg/VirtioNetDxe/SnpInitialize.c b/OvmfPkg/VirtioNetDxe/SnpInitialize.c
index 0ecfe044a977..be2761d3d068 100644
--- a/OvmfPkg/VirtioNetDxe/SnpInitialize.c
+++ b/OvmfPkg/VirtioNetDxe/SnpInitialize.c
@@ -35,6 +35,7 @@
                            the network device.
   @param[out]    Ring      The virtio-ring inside the VNET_DEV structure,
                            corresponding to Selector.
+  @param[out]    Mapping   A token return from the Map.
 
   @retval EFI_UNSUPPORTED  The queue size reported by the virtio-net device is
                            too small.
@@ -49,11 +50,13 @@ EFIAPI
 VirtioNetInitRing (
   IN OUT VNET_DEV *Dev,
   IN     UINT16   Selector,
-  OUT    VRING    *Ring
+  OUT    VRING    *Ring,
+  OUT    VOID     **Mapping
   )
 {
   EFI_STATUS Status;
   UINT16     QueueSize;
+  UINT64     RingBaseShift;
 
   //
   // step 4b -- allocate selected queue
@@ -79,30 +82,37 @@ VirtioNetInitRing (
     return Status;
   }
 
+  Status = VirtioRingMap (Dev->VirtIo, Ring, &RingBaseShift, Mapping);
+  if (EFI_ERROR (Status)) {
+    goto ReleaseQueue;
+  }
+
   //
   // Additional steps for MMIO: align the queue appropriately, and set the
   // size. If anything fails from here on, we must release the ring resources.
   //
   Status = Dev->VirtIo->SetQueueNum (Dev->VirtIo, QueueSize);
   if (EFI_ERROR (Status)) {
-    goto ReleaseQueue;
+    goto UnmapQueue;
   }
 
   Status = Dev->VirtIo->SetQueueAlign (Dev->VirtIo, EFI_PAGE_SIZE);
   if (EFI_ERROR (Status)) {
-    goto ReleaseQueue;
+    goto UnmapQueue;
   }
 
   //
   // step 4c -- report GPFN (guest-physical frame number) of queue
   //
-  Status = Dev->VirtIo->SetQueueAddress (Dev->VirtIo, Ring, 0);
+  Status = Dev->VirtIo->SetQueueAddress (Dev->VirtIo, Ring, RingBaseShift);
   if (EFI_ERROR (Status)) {
-    goto ReleaseQueue;
+    goto UnmapQueue;
   }
 
   return EFI_SUCCESS;
 
+UnmapQueue:
+  Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, Mapping);
 ReleaseQueue:
   VirtioRingUninit (Dev->VirtIo, Ring);
 
@@ -456,12 +466,14 @@ VirtioNetInitialize (
   //
   // step 4b, 4c -- allocate and report virtqueues
   //
-  Status = VirtioNetInitRing (Dev, VIRTIO_NET_Q_RX, &Dev->RxRing);
+  Status = VirtioNetInitRing (Dev, VIRTIO_NET_Q_RX, &Dev->RxRing,
+             &Dev->RxRingMap);
   if (EFI_ERROR (Status)) {
     goto DeviceFailed;
   }
 
-  Status = VirtioNetInitRing (Dev, VIRTIO_NET_Q_TX, &Dev->TxRing);
+  Status = VirtioNetInitRing (Dev, VIRTIO_NET_Q_TX, &Dev->TxRing,
+             &Dev->TxRingMap);
   if (EFI_ERROR (Status)) {
     goto ReleaseRxRing;
   }
@@ -510,9 +522,11 @@ AbortDevice:
   Dev->VirtIo->SetDeviceStatus (Dev->VirtIo, 0);
 
 ReleaseTxRing:
+  Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, Dev->TxRingMap);
   VirtioRingUninit (Dev->VirtIo, &Dev->TxRing);
 
 ReleaseRxRing:
+  Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, Dev->RxRingMap);
   VirtioRingUninit (Dev->VirtIo, &Dev->RxRing);
 
 DeviceFailed:
-- 
2.7.4

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