diff mbox

[edk2,wave,3,v2,13/17] OvmfPkg: VirtioScsiDxe: adapt feature negotiation to virtio-1.0

Message ID 1459946427-15771-14-git-send-email-lersek@redhat.com
State New
Headers show

Commit Message

Laszlo Ersek April 6, 2016, 12:40 p.m. UTC 
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>

---
 OvmfPkg/VirtioScsiDxe/VirtioScsi.c | 27 +++++++++++++++-----
 1 file changed, 20 insertions(+), 7 deletions(-)

-- 
1.8.3.1


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diff mbox

Patch

diff --git a/OvmfPkg/VirtioScsiDxe/VirtioScsi.c b/OvmfPkg/VirtioScsiDxe/VirtioScsi.c
index 162577bcb961..c080404330e5 100644
--- a/OvmfPkg/VirtioScsiDxe/VirtioScsi.c
+++ b/OvmfPkg/VirtioScsiDxe/VirtioScsi.c
@@ -796,14 +796,27 @@  VirtioScsiInit (
     // We must be able to halve it for bidirectional transfers
     // (see EFI_BAD_BUFFER_SIZE in PopulateRequest()).
     //
     Status = EFI_UNSUPPORTED;
     goto Failed;
   }
 
+  Features &= VIRTIO_SCSI_F_INOUT | 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 Failed;
+    }
+  }
+
   //
   // step 4b -- allocate request virtqueue
   //
   Status = Dev->VirtIo->SetQueueSel (Dev->VirtIo, VIRTIO_SCSI_REQUEST_QUEUE);
   if (EFI_ERROR (Status)) {
     goto Failed;
   }
@@ -843,22 +856,22 @@  VirtioScsiInit (
   //
   Status = Dev->VirtIo->SetQueueAddress (Dev->VirtIo, &Dev->Ring);
   if (EFI_ERROR (Status)) {
     goto ReleaseQueue;
   }
 
   //
-  // step 5 -- Report understood features and guest-tuneables. We want none of
-  // the known (or unknown) VIRTIO_SCSI_F_* or VIRTIO_F_* capabilities (see
-  // virtio-0.9.5, Appendices B and I), except bidirectional transfers.
+  // step 5 -- Report understood features and guest-tuneables.
   //
-  Status = Dev->VirtIo->SetGuestFeatures (Dev->VirtIo,
-      Features & VIRTIO_SCSI_F_INOUT);
-  if (EFI_ERROR (Status)) {
-    goto ReleaseQueue;
+  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 ReleaseQueue;
+    }
   }
 
   //
   // We expect these maximum sizes from the host. Since they are
   // guest-negotiable, ask for them rather than just checking them.
   //
   Status = VIRTIO_CFG_WRITE (Dev, CdbSize, VIRTIO_SCSI_CDB_SIZE);