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

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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
This commit is contained in:
jljusten
2012-10-12 18:54:35 +00:00
parent 7fcacd6c92
commit e371e7e545
4 changed files with 205 additions and 66 deletions
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58
OvmfPkg/VirtioBlkDxe/VirtioBlk.c
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@@ -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
@@ -292,17 +286,11 @@ 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;
}