OvmfPkg: VirtioBlkDxe: 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/VirtioBlkDxe/VirtioBlk.c b/OvmfPkg/VirtioBlkDxe/VirtioBlk.c
index 8257effac22d829df8407f98b12680c22a2f0487..f1c3f87e202700451e7286475cd22217a0167398 100644 (file)
--- a/OvmfPkg/VirtioBlkDxe/VirtioBlk.c
+++ b/OvmfPkg/VirtioBlkDxe/VirtioBlk.c
@@ -692,6 +692,20 @@ VirtioBlkInit (
     }\r
   }\r
 \r
+  Features &= VIRTIO_BLK_F_BLK_SIZE | VIRTIO_BLK_F_TOPOLOGY | VIRTIO_BLK_F_RO |\r
+              VIRTIO_BLK_F_FLUSH | 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 Failed;\r
+    }\r
+  }\r
+\r
   //\r
   // step 4b -- allocate virtqueue\r
   //\r
@@ -739,11 +753,12 @@ VirtioBlkInit (
   //\r
   // step 5 -- Report understood features.\r
   //\r
-  Features &= VIRTIO_BLK_F_BLK_SIZE | VIRTIO_BLK_F_TOPOLOGY | VIRTIO_BLK_F_RO |\r
-              VIRTIO_BLK_F_FLUSH;\r
-  Status = Dev->VirtIo->SetGuestFeatures (Dev->VirtIo, Features);\r
-  if (EFI_ERROR (Status)) {\r
-    goto ReleaseQueue;\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 ReleaseQueue;\r
+    }\r
   }\r
 \r
   //\r