OvmfPkg: librarize reusable bits from VirtioBlkDxe's SynchronousRequest()

new VirtioLib functions:
- VirtioPrepare(): prepare for appending descriptors
- VirtioFlush(): submit descriptor chain and await host answer

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@13844 6f19259b-4bc3-4df7-8a09-765794883524

1 files changed, 8 insertions, 50 deletions

diff --git a/OvmfPkg/VirtioBlkDxe/VirtioBlk.c b/OvmfPkg/VirtioBlkDxe/VirtioBlk.c
index ce38ff7093..44a05cfb5f 100644
--- a/OvmfPkg/VirtioBlkDxe/VirtioBlk.c
+++ b/OvmfPkg/VirtioBlkDxe/VirtioBlk.c
@@ -248,9 +248,7 @@ SynchronousRequest (
   UINT32                  BlockSize;

   volatile VIRTIO_BLK_REQ Request;

   volatile UINT8          HostStatus;

-  UINT16                  FirstAvailIdx;

-  UINT16                  NextAvailIdx;

-  UINTN                   PollPeriodUsecs;

+  DESC_INDICES            Indices;

 

   BlockSize = Dev->BlockIoMedia.BlockSize;

 

@@ -275,11 +273,7 @@ SynchronousRequest (
   Request.IoPrio = 0;

   Request.Sector = Lba * (BlockSize / 512);

 

-  //

-  // Prepare for virtio-0.9.5, 2.4.2 Receiving Used Buffers From the Device.

-  // We're going to poll the answer, the host should not send an interrupt.

-  //

-  *Dev->Ring.Avail.Flags = (UINT16) VRING_AVAIL_F_NO_INTERRUPT;

+  VirtioPrepare (&Dev->Ring, &Indices);

 

   //

   // preset a host status for ourselves that we do not accept as success

@@ -293,16 +287,10 @@ SynchronousRequest (
   ASSERT (Dev->Ring.QueueSize >= 3);

 

   //

-  // Implement virtio-0.9.5, 2.4.1 Supplying Buffers to the Device.

-  //

-  FirstAvailIdx = *Dev->Ring.Avail.Idx;

-  NextAvailIdx  = FirstAvailIdx;

-

-  //

   // virtio-blk header in first desc

   //

   VirtioAppendDesc (&Dev->Ring, (UINTN) &Request, sizeof Request,

-    VRING_DESC_F_NEXT, FirstAvailIdx, &NextAvailIdx);

+    VRING_DESC_F_NEXT, &Indices);

 

   //

   // data buffer for read/write in second desc

@@ -323,50 +311,20 @@ SynchronousRequest (
     //

     VirtioAppendDesc (&Dev->Ring, (UINTN) Buffer, (UINT32) BufferSize,

       VRING_DESC_F_NEXT | (RequestIsWrite ? 0 : VRING_DESC_F_WRITE),

-      FirstAvailIdx, &NextAvailIdx);

+      &Indices);

   }

 

   //

   // host status in last (second or third) desc

   //

   VirtioAppendDesc (&Dev->Ring, (UINTN) &HostStatus, sizeof HostStatus,

-    VRING_DESC_F_WRITE, FirstAvailIdx, &NextAvailIdx);

+    VRING_DESC_F_WRITE, &Indices);

 

   //

-  // virtio-0.9.5, 2.4.1.3 Updating the Index Field

+  // virtio-blk's only virtqueue is #0, called "requestq" (see Appendix D).

   //

-  MemoryFence();

-  *Dev->Ring.Avail.Idx = NextAvailIdx;

-

-  //

-  // virtio-0.9.5, 2.4.1.4 Notifying the Device -- gratuitous notifications are

-  // OK. virtio-blk's only virtqueue is #0, called "requestq" (see Appendix D).

-  //

-  MemoryFence();

-  if (EFI_ERROR (VIRTIO_CFG_WRITE (Dev, Generic.VhdrQueueNotify, 0))) {

-    return EFI_DEVICE_ERROR;

-  }

-

-  //

-  // virtio-0.9.5, 2.4.2 Receiving Used Buffers From the Device

-  // Wait until the host processes and acknowledges our 3-part descriptor

-  // chain. The condition we use for polling is greatly simplified and relies

-  // on synchronous, the lock-step progress.

-  //

-  // Keep slowing down until we reach a poll period of slightly above 1 ms.

-  //

-  PollPeriodUsecs = 1;

-  MemoryFence();

-  while (*Dev->Ring.Used.Idx != NextAvailIdx) {

-    gBS->Stall (PollPeriodUsecs); // calls AcpiTimerLib::MicroSecondDelay

-

-    if (PollPeriodUsecs < 1024) {

-      PollPeriodUsecs *= 2;

-    }

-    MemoryFence();

-  }

-

-  if (HostStatus == VIRTIO_BLK_S_OK) {

+  if (VirtioFlush (Dev->PciIo, 0, &Dev->Ring, &Indices) == EFI_SUCCESS &&

+      HostStatus == VIRTIO_BLK_S_OK) {

     return EFI_SUCCESS;

   }