When device is behind the IOMMU then driver need to pass the device
address when programing the bus master. The patch uses VirtioRingMap() to
map the VRING system physical address to device address.

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
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
 OvmfPkg/VirtioScsiDxe/VirtioScsi.h |  1 +
 OvmfPkg/VirtioScsiDxe/VirtioScsi.c | 47 +++++++++++++++-----
 2 files changed, 38 insertions(+), 10 deletions(-)

diff --git a/OvmfPkg/VirtioScsiDxe/VirtioScsi.h b/OvmfPkg/VirtioScsiDxe/VirtioScsi.h
index 6d00567e8cb8..05a6bf567263 100644
--- a/OvmfPkg/VirtioScsiDxe/VirtioScsi.h
+++ b/OvmfPkg/VirtioScsiDxe/VirtioScsi.h
@@ -60,6 +60,7 @@ typedef struct {
   VRING                           Ring;           // VirtioRingInit      2
   EFI_EXT_SCSI_PASS_THRU_PROTOCOL PassThru;       // VirtioScsiInit      1
   EFI_EXT_SCSI_PASS_THRU_MODE     PassThruMode;   // VirtioScsiInit      1
+  VOID                            *RingMap;       // VirtioRingMap       2
 } VSCSI_DEV;
 
 #define VIRTIO_SCSI_FROM_PASS_THRU(PassThruPointer) \
diff --git a/OvmfPkg/VirtioScsiDxe/VirtioScsi.c b/OvmfPkg/VirtioScsiDxe/VirtioScsi.c
index a983b3df7b9c..5e72b1a24b59 100644
--- a/OvmfPkg/VirtioScsiDxe/VirtioScsi.c
+++ b/OvmfPkg/VirtioScsiDxe/VirtioScsi.c
@@ -707,7 +707,7 @@ VirtioScsiInit (
 {
   UINT8      NextDevStat;
   EFI_STATUS Status;
-
+  UINT64     RingBaseShift;
   UINT64     Features;
   UINT16     MaxChannel; // for validation only
   UINT32     NumQueues;  // for validation only
@@ -839,25 +839,42 @@ VirtioScsiInit (
   }
 
   //
+  // 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;
   }
 
   //
@@ -867,7 +884,7 @@ VirtioScsiInit (
     Features &= ~(UINT64)VIRTIO_F_VERSION_1;
     Status = Dev->VirtIo->SetGuestFeatures (Dev->VirtIo, Features);
     if (EFI_ERROR (Status)) {
-      goto ReleaseQueue;
+      goto UnmapQueue;
     }
   }
 
@@ -877,11 +894,11 @@ VirtioScsiInit (
   //
   Status = VIRTIO_CFG_WRITE (Dev, CdbSize, VIRTIO_SCSI_CDB_SIZE);
   if (EFI_ERROR (Status)) {
-    goto ReleaseQueue;
+    goto UnmapQueue;
   }
   Status = VIRTIO_CFG_WRITE (Dev, SenseSize, VIRTIO_SCSI_SENSE_SIZE);
   if (EFI_ERROR (Status)) {
-    goto ReleaseQueue;
+    goto UnmapQueue;
   }
 
   //
@@ -890,7 +907,7 @@ VirtioScsiInit (
   NextDevStat |= VSTAT_DRIVER_OK;
   Status = Dev->VirtIo->SetDeviceStatus (Dev->VirtIo, NextDevStat);
   if (EFI_ERROR (Status)) {
-    goto ReleaseQueue;
+    goto UnmapQueue;
   }
 
   //
@@ -926,6 +943,9 @@ VirtioScsiInit (
 
   return EFI_SUCCESS;
 
+UnmapQueue:
+  Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, Dev->RingMap);
+
 ReleaseQueue:
   VirtioRingUninit (Dev->VirtIo, &Dev->Ring);
 
@@ -965,6 +985,7 @@ VirtioScsiUninit (
   Dev->MaxLun         = 0;
   Dev->MaxSectors     = 0;
 
+  Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, Dev->RingMap);
   VirtioRingUninit (Dev->VirtIo, &Dev->Ring);
 
   SetMem (&Dev->PassThru,     sizeof Dev->PassThru,     0x00);
@@ -995,6 +1016,12 @@ VirtioScsiExitBoot (
   //
   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);
 }
 
 
-- 
2.7.4

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