[PATCH v2 23/23] OvmfPkg/Virtio: define VIRITO_F_IOMMU_PLATFORM feature bit

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

This feature indicates that the device is behind an IOMMU that translates
bus addresses from the device into physical addresses in memory.  If this
feature bit is set to 0, then the device emits physical addresses which
are not translated further, even though an IOMMU may be present.
see [1] for more infromation

[1] https://lists.oasis-open.org/archives/virtio-dev/201610/msg00121.html

In previous patches, we have implemented IOMMU-like member functions in
VIRTIO_DEVICE_PROTOCOL to translate the physical address to bus address
and virtio drivers are updated to use those member functions. We do not
need to do anything special when VIRTIO_F_IOMMU_PLATFORM bit is present
hence treat it in parallel with VIRTIO_F_VERSION_1.

Suggested-by: Laszlo Ersek <lersek@redhat.com>
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/Include/IndustryStandard/Virtio10.h | 5 +++++
 OvmfPkg/VirtioBlkDxe/VirtioBlk.c            | 3 ++-
 OvmfPkg/VirtioNetDxe/SnpInitialize.c        | 3 ++-
 OvmfPkg/VirtioRngDxe/VirtioRng.c            | 2 +-
 OvmfPkg/VirtioScsiDxe/VirtioScsi.c          | 3 ++-
 5 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/OvmfPkg/Include/IndustryStandard/Virtio10.h b/OvmfPkg/Include/IndustryStandard/Virtio10.h
index 4c9b62a3cf59..c62429d94432 100644
--- a/OvmfPkg/Include/IndustryStandard/Virtio10.h
+++ b/OvmfPkg/Include/IndustryStandard/Virtio10.h
@@ -83,4 +83,9 @@ typedef struct {
 //
 #define VIRTIO_F_VERSION_1 BIT32
 
+//
+// VirtIo 1.0 reserved iommu platform feature bits
+//
+#define VIRTIO_F_IOMMU_PLATFORM BIT33
+
 #endif // _VIRTIO_1_0_H_
diff --git a/OvmfPkg/VirtioBlkDxe/VirtioBlk.c b/OvmfPkg/VirtioBlkDxe/VirtioBlk.c
index 57baceb20a19..a78ec0df9c7b 100644
--- a/OvmfPkg/VirtioBlkDxe/VirtioBlk.c
+++ b/OvmfPkg/VirtioBlkDxe/VirtioBlk.c
@@ -773,7 +773,8 @@ VirtioBlkInit (
   }
 
   Features &= VIRTIO_BLK_F_BLK_SIZE | VIRTIO_BLK_F_TOPOLOGY | VIRTIO_BLK_F_RO |
-              VIRTIO_BLK_F_FLUSH | VIRTIO_F_VERSION_1;
+              VIRTIO_BLK_F_FLUSH | VIRTIO_F_VERSION_1 |
+              VIRTIO_F_IOMMU_PLATFORM;
 
   //
   // In virtio-1.0, feature negotiation is expected to complete before queue
diff --git a/OvmfPkg/VirtioNetDxe/SnpInitialize.c b/OvmfPkg/VirtioNetDxe/SnpInitialize.c
index 9bac19f8e3d1..b389f6243661 100644
--- a/OvmfPkg/VirtioNetDxe/SnpInitialize.c
+++ b/OvmfPkg/VirtioNetDxe/SnpInitialize.c
@@ -536,7 +536,8 @@ VirtioNetInitialize (
   ASSERT (Dev->Snm.MediaPresentSupported ==
     !!(Features & VIRTIO_NET_F_STATUS));
 
-  Features &= VIRTIO_NET_F_MAC | VIRTIO_NET_F_STATUS | VIRTIO_F_VERSION_1;
+  Features &= VIRTIO_NET_F_MAC | VIRTIO_NET_F_STATUS | VIRTIO_F_VERSION_1 |
+              VIRTIO_F_IOMMU_PLATFORM;
 
   //
   // In virtio-1.0, feature negotiation is expected to complete before queue
diff --git a/OvmfPkg/VirtioRngDxe/VirtioRng.c b/OvmfPkg/VirtioRngDxe/VirtioRng.c
index b19d90901430..81d8c7facc10 100644
--- a/OvmfPkg/VirtioRngDxe/VirtioRng.c
+++ b/OvmfPkg/VirtioRngDxe/VirtioRng.c
@@ -273,7 +273,7 @@ VirtioRngInit (
     goto Failed;
   }
 
-  Features &= VIRTIO_F_VERSION_1;
+  Features &= VIRTIO_F_VERSION_1 | VIRTIO_F_IOMMU_PLATFORM;
 
   //
   // In virtio-1.0, feature negotiation is expected to complete before queue
diff --git a/OvmfPkg/VirtioScsiDxe/VirtioScsi.c b/OvmfPkg/VirtioScsiDxe/VirtioScsi.c
index 65e9bda0827a..286b005c994c 100644
--- a/OvmfPkg/VirtioScsiDxe/VirtioScsi.c
+++ b/OvmfPkg/VirtioScsiDxe/VirtioScsi.c
@@ -903,7 +903,8 @@ VirtioScsiInit (
     goto Failed;
   }
 
-  Features &= VIRTIO_SCSI_F_INOUT | VIRTIO_F_VERSION_1;
+  Features &= VIRTIO_SCSI_F_INOUT | VIRTIO_F_VERSION_1 |
+              VIRTIO_F_IOMMU_PLATFORM;
 
   //
   // In virtio-1.0, feature negotiation is expected to complete before queue
-- 
2.7.4