[PATCH v3 3/4] OvmfPkg/VirtioScsiDxe: map virtio-scsi request and response buffers

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

When device is behind the IOMMU, driver is require to pass the device
address of virtio request, response and any memory referenced by those
request/response to the bus master.

The patch uses IOMMU-like member functions from VIRTIO_DEVICE_PROTOCOL to
map request and response buffers system physical address to the device
address.

- If the buffer need to be accessed by both the processor and a bus
  master then map with BusMasterCommonBuffer.

  However, after a BusMasterWrite Unmap() failure, error reporting via
  EFI_EXT_SCSI_PASS_THRU_SCSI_REQUEST_PACKET would be very complex,
  therefore we map such buffers too with BusMasterCommonBuffer.

- If the buffer need to be accessed for a read  operation by a bus master
  then map with BusMasterRead.

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/VirtioScsiDxe/VirtioScsi.c | 220 ++++++++++++++++++--
 1 file changed, 204 insertions(+), 16 deletions(-)

diff --git a/OvmfPkg/VirtioScsiDxe/VirtioScsi.c b/OvmfPkg/VirtioScsiDxe/VirtioScsi.c
index 5e977c636a0a..337fb4b2f1e0 100644
--- a/OvmfPkg/VirtioScsiDxe/VirtioScsi.c
+++ b/OvmfPkg/VirtioScsiDxe/VirtioScsi.c
@@ -436,26 +436,156 @@ VirtioScsiPassThru (
   UINT16                    TargetValue;
   EFI_STATUS                Status;
   volatile VIRTIO_SCSI_REQ  Request;
-  volatile VIRTIO_SCSI_RESP Response;
+  volatile VIRTIO_SCSI_RESP *Response;
+  VOID                      *ResponseBuffer;
   DESC_INDICES              Indices;
+  VOID                      *RequestMapping;
+  VOID                      *ResponseMapping;
+  VOID                      *InDataMapping;
+  VOID                      *OutDataMapping;
+  EFI_PHYSICAL_ADDRESS      RequestDeviceAddress;
+  EFI_PHYSICAL_ADDRESS      ResponseDeviceAddress;
+  EFI_PHYSICAL_ADDRESS      InDataDeviceAddress;
+  EFI_PHYSICAL_ADDRESS      OutDataDeviceAddress;
+  VOID                      *InDataBuffer;
+  UINTN                     InDataNumPages;
+  BOOLEAN                   OutDataBufferIsMapped;
 
   ZeroMem ((VOID*) &Request, sizeof (Request));
-  ZeroMem ((VOID*) &Response, sizeof (Response));
 
   Dev = VIRTIO_SCSI_FROM_PASS_THRU (This);
   CopyMem (&TargetValue, Target, sizeof TargetValue);
 
+  InDataBuffer = NULL;
+  OutDataBufferIsMapped = FALSE;
+  InDataNumPages = 0;
+
   Status = PopulateRequest (Dev, TargetValue, Lun, Packet, &Request);
   if (EFI_ERROR (Status)) {
     return Status;
   }
 
-  VirtioPrepare (&Dev->Ring, &Indices);
+  //
+  // Map the virtio-scsi Request header buffer
+  //
+  Status = VirtioMapAllBytesInSharedBuffer (
+             Dev->VirtIo,
+             VirtioOperationBusMasterRead,
+             (VOID *) &Request,
+             sizeof Request,
+             &RequestDeviceAddress,
+             &RequestMapping);
+  if (EFI_ERROR (Status)) {
+    return ReportHostAdapterError (Packet);
+  }
+
+  //
+  // Map the input buffer
+  //
+  if (Packet->InTransferLength > 0) {
+    //
+    // Allocate a intermediate input buffer. This is mainly to handle the
+    // following case:
+    //  * caller submits a bi-directional request
+    //  * we perform the request fine
+    //  * but we fail to unmap the "InDataMapping"
+    //
+    //  In that case simply returing the EFI_DEVICE_ERROR is not sufficient.
+    //  In addition to the error code we also need to update Packet fields
+    //  accordingly so that we report the full loss of the incoming transfer.
+    //  We allocate a temporary buffer and map it with BusMasterCommonBuffer.
+    //  If the Virtio request is successful then we copy the data from
+    //  temporary buffer into Packet->InDataBuffer.
+    //
+    InDataNumPages = (UINTN)EFI_SIZE_TO_PAGES (Packet->InTransferLength);
+    Status = Dev->VirtIo->AllocateSharedPages (
+                            Dev->VirtIo,
+                            InDataNumPages,
+                            &InDataBuffer
+                            );
+    if (EFI_ERROR (Status)) {
+      Status = ReportHostAdapterError (Packet);
+      goto UnmapRequestBuffer;
+    }
+
+    ZeroMem (InDataBuffer, Packet->InTransferLength);
+
+    Status = VirtioMapAllBytesInSharedBuffer (
+               Dev->VirtIo,
+               VirtioOperationBusMasterCommonBuffer,
+               InDataBuffer,
+               Packet->InTransferLength,
+               &InDataDeviceAddress,
+               &InDataMapping
+               );
+    if (EFI_ERROR (Status)) {
+      Status = ReportHostAdapterError (Packet);
+      goto FreeInDataBuffer;
+    }
+  }
+
+  //
+  // Map the output buffer
+  //
+  if (Packet->OutTransferLength > 0) {
+    Status = VirtioMapAllBytesInSharedBuffer (
+               Dev->VirtIo,
+               VirtioOperationBusMasterRead,
+               Packet->OutDataBuffer,
+               Packet->OutTransferLength,
+               &OutDataDeviceAddress,
+               &OutDataMapping
+               );
+    if (EFI_ERROR (Status)) {
+      Status = ReportHostAdapterError (Packet);
+      goto UnmapInDataBuffer;
+    }
+
+    OutDataBufferIsMapped = TRUE;
+  }
+
+  //
+  // Response header is bi-direction (we preset with host status and expect
+  // the device to update it). Allocate a response buffer which can be mapped
+  // to access equally by both processor and device.
+  //
+  Status = Dev->VirtIo->AllocateSharedPages (
+                          Dev->VirtIo,
+                          EFI_SIZE_TO_PAGES (sizeof *Response),
+                          &ResponseBuffer
+                          );
+  if (EFI_ERROR (Status)) {
+    Status = ReportHostAdapterError (Packet);
+    goto UnmapOutDataBuffer;
+  }
+
+  Response = ResponseBuffer;
+
+  ZeroMem ((VOID *)Response, sizeof (*Response));
 
   //
   // preset a host status for ourselves that we do not accept as success
   //
-  Response.Response = VIRTIO_SCSI_S_FAILURE;
+  Response->Response = VIRTIO_SCSI_S_FAILURE;
+
+  //
+  // Map the response buffer with BusMasterCommonBuffer so that response
+  // buffer can be accessed by both host and device.
+  //
+  Status = VirtioMapAllBytesInSharedBuffer (
+             Dev->VirtIo,
+             VirtioOperationBusMasterCommonBuffer,
+             ResponseBuffer,
+             sizeof (*Response),
+             &ResponseDeviceAddress,
+             &ResponseMapping
+             );
+  if (EFI_ERROR (Status)) {
+    Status = ReportHostAdapterError (Packet);
+    goto FreeResponseBuffer;
+  }
+
+  VirtioPrepare (&Dev->Ring, &Indices);
 
   //
   // ensured by VirtioScsiInit() -- this predicate, in combination with the
@@ -466,31 +596,49 @@ VirtioScsiPassThru (
   //
   // enqueue Request
   //
-  VirtioAppendDesc (&Dev->Ring, (UINTN) &Request, sizeof Request,
-    VRING_DESC_F_NEXT, &Indices);
+  VirtioAppendDesc (
+    &Dev->Ring,
+    RequestDeviceAddress,
+    sizeof Request,
+    VRING_DESC_F_NEXT,
+    &Indices
+    );
 
   //
   // enqueue "dataout" if any
   //
   if (Packet->OutTransferLength > 0) {
-    VirtioAppendDesc (&Dev->Ring, (UINTN) Packet->OutDataBuffer,
-      Packet->OutTransferLength, VRING_DESC_F_NEXT, &Indices);
+    VirtioAppendDesc (
+      &Dev->Ring,
+      OutDataDeviceAddress,
+      Packet->OutTransferLength,
+      VRING_DESC_F_NEXT,
+      &Indices
+      );
   }
 
   //
   // enqueue Response, to be written by the host
   //
-  VirtioAppendDesc (&Dev->Ring, (UINTN) &Response, sizeof Response,
-    VRING_DESC_F_WRITE | (Packet->InTransferLength > 0 ?
-                          VRING_DESC_F_NEXT : 0),
-    &Indices);
+  VirtioAppendDesc (
+    &Dev->Ring,
+    ResponseDeviceAddress,
+    sizeof *Response,
+    VRING_DESC_F_WRITE | (Packet->InTransferLength > 0 ? VRING_DESC_F_NEXT : 0),
+    &Indices
+    );
 
   //
   // enqueue "datain" if any, to be written by the host
   //
   if (Packet->InTransferLength > 0) {
-    VirtioAppendDesc (&Dev->Ring, (UINTN) Packet->InDataBuffer,
-      Packet->InTransferLength, VRING_DESC_F_WRITE, &Indices);
+    VirtioAppendDesc (
+      &Dev->Ring,
+      InDataDeviceAddress,
+      Packet->InTransferLength,
+      VRING_DESC_F_WRITE,
+      &Indices
+      );
   }
 
   // If kicking the host fails, we must fake a host adapter error.
@@ -499,10 +647,50 @@ VirtioScsiPassThru (
   //
   if (VirtioFlush (Dev->VirtIo, VIRTIO_SCSI_REQUEST_QUEUE, &Dev->Ring,
         &Indices, NULL) != EFI_SUCCESS) {
-    return ReportHostAdapterError (Packet);
+    Status = ReportHostAdapterError (Packet);
+    goto UnmapResponseBuffer;
   }
 
-  return ParseResponse (Packet, &Response);
+  Status = ParseResponse (Packet, Response);
+
+  //
+  // If virtio request was successful and it was a CPU read request then we
+  // have used an intermediate buffer. Copy the data from intermediate buffer
+  // to the final buffer.
+  //
+  if (InDataBuffer != NULL) {
+    CopyMem (Packet->InDataBuffer, InDataBuffer, Packet->InTransferLength);
+  }
+
+UnmapResponseBuffer:
+  Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, ResponseMapping);
+
+FreeResponseBuffer:
+  Dev->VirtIo->FreeSharedPages (
+                 Dev->VirtIo,
+                 EFI_SIZE_TO_PAGES (sizeof *Response),
+                 ResponseBuffer
+                 );
+
+UnmapOutDataBuffer:
+  if (OutDataBufferIsMapped) {
+    Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, OutDataMapping);
+  }
+
+UnmapInDataBuffer:
+  if (InDataBuffer != NULL) {
+    Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, InDataMapping);
+  }
+
+FreeInDataBuffer:
+  if (InDataBuffer != NULL) {
+    Dev->VirtIo->FreeSharedPages (Dev->VirtIo, InDataNumPages, InDataBuffer);
+  }
+
+UnmapRequestBuffer:
+  Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, RequestMapping);
+
+  return Status;
 }
 
 
-- 
2.7.4