OvmfPkg/VirtioRngDxe: map host address to device address

patch maps the host address to a device address for buffers (including
rings, device specifc request and response pointed by vring descriptor,
and any further memory reference by those request and response).

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>
[lersek@redhat.com: return EFI_DEVICE_ERROR if mapping fails in GetRNG]
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Regression-tested-by: Laszlo Ersek <lersek@redhat.com>

2 files changed, 75 insertions, 9 deletions

diff --git a/OvmfPkg/VirtioRngDxe/VirtioRng.c b/OvmfPkg/VirtioRngDxe/VirtioRng.c
index 0abca488e6..4e67997881 100644
--- a/OvmfPkg/VirtioRngDxe/VirtioRng.c
+++ b/OvmfPkg/VirtioRngDxe/VirtioRng.c
@@ -140,6 +140,8 @@ VirtioRngGetRNG (
   UINT32                    Len;

   UINT32                    BufferSize;

   EFI_STATUS                Status;

+  EFI_PHYSICAL_ADDRESS      DeviceAddress;

+  VOID                      *Mapping;

 

   if (This == NULL || RNGValueLength == 0 || RNGValue == NULL) {

     return EFI_INVALID_PARAMETER;

@@ -159,6 +161,21 @@ VirtioRngGetRNG (
   }

 

   Dev = VIRTIO_ENTROPY_SOURCE_FROM_RNG (This);

+  //

+  // Map Buffer's system phyiscal address to device address

+  //

+  Status = VirtioMapAllBytesInSharedBuffer (

+             Dev->VirtIo,

+             VirtioOperationBusMasterWrite,

+             (VOID *)Buffer,

+             RNGValueLength,

+             &DeviceAddress,

+             &Mapping

+             );

+  if (EFI_ERROR (Status)) {

+    Status = EFI_DEVICE_ERROR;

+    goto FreeBuffer;

+  }

 

   //

   // The Virtio RNG device may return less data than we asked it to, and can

@@ -170,7 +187,7 @@ VirtioRngGetRNG (
 

     VirtioPrepare (&Dev->Ring, &Indices);

     VirtioAppendDesc (&Dev->Ring,

-      (UINTN)Buffer + Index,

+      DeviceAddress + Index,

       BufferSize,

       VRING_DESC_F_WRITE,

       &Indices);

@@ -178,17 +195,35 @@ VirtioRngGetRNG (
     if (VirtioFlush (Dev->VirtIo, 0, &Dev->Ring, &Indices, &Len) !=

         EFI_SUCCESS) {

       Status = EFI_DEVICE_ERROR;

-      goto FreeBuffer;

+      goto UnmapBuffer;

     }

     ASSERT (Len > 0);

     ASSERT (Len <= BufferSize);

   }

 

+  //

+  // Unmap the device buffer before accessing it.

+  //

+  Status = Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, Mapping);

+  if (EFI_ERROR (Status)) {

+    Status = EFI_DEVICE_ERROR;

+    goto FreeBuffer;

+  }

+

   for (Index = 0; Index < RNGValueLength; Index++) {

     RNGValue[Index] = Buffer[Index];

   }

   Status = EFI_SUCCESS;

 

+UnmapBuffer:

+  //

+  // If we are reached here due to the error then unmap the buffer otherwise

+  // the buffer is already unmapped after VirtioFlush().

+  //

+  if (EFI_ERROR (Status)) {

+    Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, Mapping);

+  }

+

 FreeBuffer:

   FreePool ((VOID *)Buffer);

   return Status;

@@ -205,6 +240,7 @@ VirtioRngInit (
   EFI_STATUS Status;

   UINT16     QueueSize;

   UINT64     Features;

+  UINT64     RingBaseShift;

 

   //

   // Execute virtio-0.9.5, 2.2.1 Device Initialization Sequence.

@@ -282,25 +318,42 @@ VirtioRngInit (
   }

 

   //

+  // If anything fails from here on, we must release the ring resources.

+  //

+  Status = VirtioRingMap (

+             Dev->VirtIo,

+             &Dev->Ring,

+             &RingBaseShift,

+             &Dev->RingMap

+             );

+  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.

+  // size. If anything fails from here on, we must unmap 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, &Dev->Ring, 0);

+  Status = Dev->VirtIo->SetQueueAddress (

+                          Dev->VirtIo,

+                          &Dev->Ring,

+                          RingBaseShift

+                          );

   if (EFI_ERROR (Status)) {

-    goto ReleaseQueue;

+    goto UnmapQueue;

   }

 

   //

@@ -310,7 +363,7 @@ VirtioRngInit (
     Features &= ~(UINT64)VIRTIO_F_VERSION_1;

     Status = Dev->VirtIo->SetGuestFeatures (Dev->VirtIo, Features);

     if (EFI_ERROR (Status)) {

-      goto ReleaseQueue;

+      goto UnmapQueue;

     }

   }

 

@@ -320,7 +373,7 @@ VirtioRngInit (
   NextDevStat |= VSTAT_DRIVER_OK;

   Status = Dev->VirtIo->SetDeviceStatus (Dev->VirtIo, NextDevStat);

   if (EFI_ERROR (Status)) {

-    goto ReleaseQueue;

+    goto UnmapQueue;

   }

 

   //

@@ -331,6 +384,9 @@ VirtioRngInit (
 

   return EFI_SUCCESS;

 

+UnmapQueue:

+  Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, Dev->RingMap);

+

 ReleaseQueue:

   VirtioRingUninit (Dev->VirtIo, &Dev->Ring);

 

@@ -359,6 +415,9 @@ VirtioRngUninit (
   // the old comms area.

   //

   Dev->VirtIo->SetDeviceStatus (Dev->VirtIo, 0);

+

+  Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, Dev->RingMap);

+

   VirtioRingUninit (Dev->VirtIo, &Dev->Ring);

 }

 

@@ -385,6 +444,12 @@ VirtioRngExitBoot (
   //

   Dev = Context;

   Dev->VirtIo->SetDeviceStatus (Dev->VirtIo, 0);

+

+  //

+  // Unmap the ring buffer so that hypervisor will not be able to get readable

+  // data after device reset.

+  //

+  Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, Dev->RingMap);

 }

 

 

diff --git a/OvmfPkg/VirtioRngDxe/VirtioRng.h b/OvmfPkg/VirtioRngDxe/VirtioRng.h
index 998f9fae48..389c8ddc8d 100644
--- a/OvmfPkg/VirtioRngDxe/VirtioRng.h
+++ b/OvmfPkg/VirtioRngDxe/VirtioRng.h
@@ -38,6 +38,7 @@ typedef struct {
   EFI_EVENT                 ExitBoot;       // DriverBindingStart   0

   VRING                     Ring;           // VirtioRingInit       2

   EFI_RNG_PROTOCOL          Rng;            // VirtioRngInit        1

+  VOID                      *RingMap;       // VirtioRingMap        2

 } VIRTIO_RNG_DEV;

 

 #define VIRTIO_ENTROPY_SOURCE_FROM_RNG(RngPointer) \