From: Laszlo Ersek <lersek@redhat.com>
Date: Sat, 12 Mar 2016 13:41:26 +0000 (+0100)
Subject: OvmfPkg: VirtioNetDxe: adapt feature negotiation to virtio-1.0
X-Git-Tag: edk2-stable201903~7412
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=33c6b934bf973bd3e0f72805ad723558cfffaa7f;p=mirror_edk2.git

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 f06b0a5a57..38012a0df8 100644
--- a/OvmfPkg/VirtioNetDxe/SnpInitialize.c
+++ b/OvmfPkg/VirtioNetDxe/SnpInitialize.c
@@ -417,6 +417,19 @@ VirtioNetInitialize (
   ASSERT (Dev->Snm.MediaPresentSupported ==
     !!(Features & VIRTIO_NET_F_STATUS));
 
+  Features &= VIRTIO_NET_F_MAC | VIRTIO_NET_F_STATUS | VIRTIO_F_VERSION_1;
+
+  //
+  // In virtio-1.0, feature negotiation is expected to complete before queue
+  // discovery, and the device can also reject the selected set of features.
+  //
+  if (Dev->VirtIo->Revision >= VIRTIO_SPEC_REVISION (1, 0, 0)) {
+    Status = Virtio10WriteFeatures (Dev->VirtIo, Features, &NextDevStat);
+    if (EFI_ERROR (Status)) {
+      goto DeviceFailed;
+    }
+  }
+
   //
   // step 4b, 4c -- allocate and report virtqueues
   //
@@ -433,10 +446,12 @@ VirtioNetInitialize (
   //
   // step 5 -- keep only the features we want
   //
-  Features &= VIRTIO_NET_F_MAC | VIRTIO_NET_F_STATUS;
-  Status = Dev->VirtIo->SetGuestFeatures (Dev->VirtIo, Features);
-  if (EFI_ERROR (Status)) {
-    goto ReleaseTxRing;
+  if (Dev->VirtIo->Revision < VIRTIO_SPEC_REVISION (1, 0, 0)) {
+    Features &= ~(UINT64)VIRTIO_F_VERSION_1;
+    Status = Dev->VirtIo->SetGuestFeatures (Dev->VirtIo, Features);
+    if (EFI_ERROR (Status)) {
+      goto ReleaseTxRing;
+    }
   }
 
   //