OvmfPkg: VirtioNetDxe: adapt feature negotiation to virtio-1.0

Relative to virtio-0.9.5, virtio-1.0 reverses the order of queue discovery
and feature negotiation. In virtio-1.0, feature negotiation has to
complete first, and the device can also reject a self-inconsistent feature
request through the new VSTAT_FEATURES_OK status bit. (For example if the
driver requests a higher level feature but clears a prerequisite feature.)

Furthermore, we retain the VIRTIO_F_VERSION_1 feature bit if the
VIRTIO_DEVICE_PROTOCOL provider has high enough revision.

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

diff --git a/OvmfPkg/VirtioNetDxe/SnpInitialize.c b/OvmfPkg/VirtioNetDxe/SnpInitialize.c
index f06b0a5a5742bef6ea1945bfba5357d7e189f878..38012a0df8d65f763ffe85beaad64f169753c835 100644 (file)
--- a/OvmfPkg/VirtioNetDxe/SnpInitialize.c
+++ b/OvmfPkg/VirtioNetDxe/SnpInitialize.c
@@ -417,6 +417,19 @@ VirtioNetInitialize (
   ASSERT (Dev->Snm.MediaPresentSupported ==\r
     !!(Features & VIRTIO_NET_F_STATUS));\r
 \r
+  Features &= VIRTIO_NET_F_MAC | VIRTIO_NET_F_STATUS | VIRTIO_F_VERSION_1;\r
+\r
+  //\r
+  // In virtio-1.0, feature negotiation is expected to complete before queue\r
+  // discovery, and the device can also reject the selected set of features.\r
+  //\r
+  if (Dev->VirtIo->Revision >= VIRTIO_SPEC_REVISION (1, 0, 0)) {\r
+    Status = Virtio10WriteFeatures (Dev->VirtIo, Features, &NextDevStat);\r
+    if (EFI_ERROR (Status)) {\r
+      goto DeviceFailed;\r
+    }\r
+  }\r
+\r
   //\r
   // step 4b, 4c -- allocate and report virtqueues\r
   //\r
@@ -433,10 +446,12 @@ VirtioNetInitialize (
   //\r
   // step 5 -- keep only the features we want\r
   //\r
-  Features &= VIRTIO_NET_F_MAC | VIRTIO_NET_F_STATUS;\r
-  Status = Dev->VirtIo->SetGuestFeatures (Dev->VirtIo, Features);\r
-  if (EFI_ERROR (Status)) {\r
-    goto ReleaseTxRing;\r
+  if (Dev->VirtIo->Revision < VIRTIO_SPEC_REVISION (1, 0, 0)) {\r
+    Features &= ~(UINT64)VIRTIO_F_VERSION_1;\r
+    Status = Dev->VirtIo->SetGuestFeatures (Dev->VirtIo, Features);\r
+    if (EFI_ERROR (Status)) {\r
+      goto ReleaseTxRing;\r
+    }\r
   }\r
 \r
   //\r