[edk2,v1,17/21] Ovmf/Xen: add Xen PV console SerialPortLib driver

This implements a SerialPortLib instance that wires up to the
PV console ring used by domU guests. Also imports the required
upstream Xen io/console.h header.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 OvmfPkg/Include/IndustryStandard/Xen/io/console.h  |  51 +++++++
 .../XenConsoleSerialPortLib.c                      | 147 +++++++++++++++++++++
 .../XenConsoleSerialPortLib.inf                    |  34 +++++
 3 files changed, 232 insertions(+)
 create mode 100644 OvmfPkg/Include/IndustryStandard/Xen/io/console.h
 create mode 100644 OvmfPkg/Library/XenConsoleSerialPortLib/XenConsoleSerialPortLib.c
 create mode 100644 OvmfPkg/Library/XenConsoleSerialPortLib/XenConsoleSerialPortLib.inf

On 23 January 2015 at 18:54, Stefano Stabellini
<stefano.stabellini@eu.citrix.com> wrote:
> On Fri, 23 Jan 2015, Ard Biesheuvel wrote:
>> This implements a SerialPortLib instance that wires up to the
>> PV console ring used by domU guests. Also imports the required
>> upstream Xen io/console.h header.
>>
>> Contributed-under: TianoCore Contribution Agreement 1.0
>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>> ---
>>  OvmfPkg/Include/IndustryStandard/Xen/io/console.h  |  51 +++++++
>>  .../XenConsoleSerialPortLib.c                      | 147 +++++++++++++++++++++
>>  .../XenConsoleSerialPortLib.inf                    |  34 +++++
>>  3 files changed, 232 insertions(+)
>>  create mode 100644 OvmfPkg/Include/IndustryStandard/Xen/io/console.h
>>  create mode 100644 OvmfPkg/Library/XenConsoleSerialPortLib/XenConsoleSerialPortLib.c
>>  create mode 100644 OvmfPkg/Library/XenConsoleSerialPortLib/XenConsoleSerialPortLib.inf
>>
>> diff --git a/OvmfPkg/Include/IndustryStandard/Xen/io/console.h b/OvmfPkg/Include/IndustryStandard/Xen/io/console.h
>> new file mode 100644
>> index 000000000000..f1caa9765bcf
>> --- /dev/null
>> +++ b/OvmfPkg/Include/IndustryStandard/Xen/io/console.h
>> @@ -0,0 +1,51 @@
>> +/******************************************************************************
>> + * console.h
>> + *
>> + * Console I/O interface for Xen guest OSes.
>> + *
>> + * Permission is hereby granted, free of charge, to any person obtaining a copy
>> + * of this software and associated documentation files (the "Software"), to
>> + * deal in the Software without restriction, including without limitation the
>> + * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
>> + * sell copies of the Software, and to permit persons to whom the Software is
>> + * furnished to do so, subject to the following conditions:
>> + *
>> + * The above copyright notice and this permission notice shall be included in
>> + * all copies or substantial portions of the Software.
>> + *
>> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
>> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
>> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
>> + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
>> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
>> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
>> + * DEALINGS IN THE SOFTWARE.
>> + *
>> + * Copyright (c) 2005, Keir Fraser
>> + */
>> +
>> +#ifndef __XEN_PUBLIC_IO_CONSOLE_H__
>> +#define __XEN_PUBLIC_IO_CONSOLE_H__
>> +
>> +typedef UINT32 XENCONS_RING_IDX;
>> +
>> +#define MASK_XENCONS_IDX(idx, ring) ((idx) & (sizeof(ring)-1))
>> +
>> +struct xencons_interface {
>> +    char in[1024];
>> +    char out[2048];
>> +    XENCONS_RING_IDX in_cons, in_prod;
>> +    XENCONS_RING_IDX out_cons, out_prod;
>> +};
>> +
>> +#endif /* __XEN_PUBLIC_IO_CONSOLE_H__ */
>> +
>> +/*
>> + * Local variables:
>> + * mode: C
>> + * c-file-style: "BSD"
>> + * c-basic-offset: 4
>> + * tab-width: 4
>> + * indent-tabs-mode: nil
>> + * End:
>> + */
>> diff --git a/OvmfPkg/Library/XenConsoleSerialPortLib/XenConsoleSerialPortLib.c b/OvmfPkg/Library/XenConsoleSerialPortLib/XenConsoleSerialPortLib.c
>> new file mode 100644
>> index 000000000000..97344dc4efb0
>> --- /dev/null
>> +++ b/OvmfPkg/Library/XenConsoleSerialPortLib/XenConsoleSerialPortLib.c
>> @@ -0,0 +1,147 @@
>> +/** @file
>> +  Xen console SerialPortLib instance
>> +
>> +  Copyright (c) 2015, Linaro Ltd. All rights reserved.<BR>
>> +
>> +  This program and the accompanying materials
>> +  are licensed and made available under the terms and conditions of the BSD License
>> +  which accompanies this distribution.  The full text of the license may be found at
>> +  http://opensource.org/licenses/bsd-license.php
>> +
>> +  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
>> +  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>> +
>> +**/
>> +
>> +#include <Base.h>
>> +#include <Uefi/UefiBaseType.h>
>> +
>> +#include <Library/BaseLib.h>
>> +#include <Library/SerialPortLib.h>
>> +#include <Library/XenHypercallLib.h>
>> +
>> +#include <IndustryStandard/Xen/io/console.h>
>> +#include <IndustryStandard/Xen/hvm/params.h>
>> +#include <IndustryStandard/Xen/event_channel.h>
>> +
>> +STATIC evtchn_send_t              mXenConsoleEventChain;
>> +STATIC struct xencons_interface   *mXenConsoleInterface;
>> +
>> +RETURN_STATUS
>> +EFIAPI
>> +SerialPortInitialize (
>> +  VOID
>> +  )
>> +{
>> +  mXenConsoleEventChain.port = (UINT32)XenHypercallHvmGetParam (HVM_PARAM_CONSOLE_EVTCHN);
>> +  mXenConsoleInterface = (struct xencons_interface *)(UINTN)
>> +    (XenHypercallHvmGetParam (HVM_PARAM_CONSOLE_PFN) << EFI_PAGE_SHIFT);
>> +
>> +  //
>> +  // No point in ASSERT'ing here as we won't be seeing the output
>> +  //
>> +  return RETURN_SUCCESS;
>> +}
>> +
>> +/**
>> +  Write data to serial device.
>> +
>> +  @param  Buffer           Point of data buffer which need to be written.
>> +  @param  NumberOfBytes    Number of output bytes which are cached in Buffer.
>> +
>> +  @retval 0                Write data failed.
>> +  @retval !0               Actual number of bytes written to serial device.
>> +
>> +**/
>> +UINTN
>> +EFIAPI
>> +SerialPortWrite (
>> +  IN UINT8     *Buffer,
>> +  IN UINTN     NumberOfBytes
>> +  )
>> +{
>> +  XENCONS_RING_IDX  Consumer, Producer;
>> +  UINTN             Sent;
>> +
>> +  if (!mXenConsoleInterface) {
>> +    return 0;
>> +  }
>> +
>> +  Consumer = mXenConsoleInterface->out_cons;
>> +  Producer = mXenConsoleInterface->out_prod;
>> +
>> +  MemoryFence ();
>> +
>> +  Sent = 0;
>> +  while (Sent < NumberOfBytes && ((Producer - Consumer) < sizeof (mXenConsoleInterface->out)))
>> +    mXenConsoleInterface->out[MASK_XENCONS_IDX(Producer++, mXenConsoleInterface->out)] = Buffer[Sent++];
>> +
>> +  MemoryFence ();
>> +
>> +  mXenConsoleInterface->out_prod = Producer;
>> +
>> +  if (Sent > 0) {
>> +    XenHypercallEventChannelOp (EVTCHNOP_send, &mXenConsoleEventChain);
>> +  }
>> +
>> +  return Sent;
>> +}
>> +
>> +/**
>> +  Read data from serial device and save the data in buffer.
>> +
>> +  @param  Buffer           Point of data buffer which need to be written.
>> +  @param  NumberOfBytes    Size of Buffer[].
>> +
>> +  @retval 0                Read data failed.
>> +  @retval !0               Actual number of bytes read from serial device.
>> +
>> +**/
>> +UINTN
>> +EFIAPI
>> +SerialPortRead (
>> +  OUT UINT8     *Buffer,
>> +  IN  UINTN     NumberOfBytes
>> +)
>> +{
>> +  XENCONS_RING_IDX  Consumer, Producer;
>> +  UINTN             Received;
>> +
>> +  if (!mXenConsoleInterface) {
>> +    return 0;
>> +  }
>> +
>> +  Consumer = mXenConsoleInterface->in_cons;
>> +  Producer = mXenConsoleInterface->in_prod;
>> +
>> +  MemoryFence ();
>> +
>> +  Received = 0;
>> +  while (Received < NumberOfBytes && Consumer < Producer)
>> +     Buffer[Received++] = mXenConsoleInterface->in[MASK_XENCONS_IDX(Consumer++, mXenConsoleInterface->in)];
>> +
>> +  MemoryFence ();
>> +
>> +  mXenConsoleInterface->in_cons = Consumer;
>> +
>> +  XenHypercallEventChannelOp (EVTCHNOP_send, &mXenConsoleEventChain);
>> +
>> +  return Received;
>> +}
>> +
>> +/**
>> +  Check to see if any data is available to be read from the debug device.
>> +
>> +  @retval TRUE       At least one byte of data is available to be read
>> +  @retval FALSE      No data is available to be read
>> +
>> +**/
>> +BOOLEAN
>> +EFIAPI
>> +SerialPortPoll (
>> +  VOID
>> +  )
>> +{
>> +  return mXenConsoleInterface &&
>> +    mXenConsoleInterface->in_cons != mXenConsoleInterface->in_prod;
>
> Do you need a memory barrier after reading in_cons and in_prod and
> before comparing them, to make sure that the view is consistent?
>

I don't think so. The memory reads both have to complete before the
comparison can be performed, and the comparison itself is not a memory
access.

>
>> +}
>> diff --git a/OvmfPkg/Library/XenConsoleSerialPortLib/XenConsoleSerialPortLib.inf b/OvmfPkg/Library/XenConsoleSerialPortLib/XenConsoleSerialPortLib.inf
>> new file mode 100644
>> index 000000000000..f7925b3e6bc3
>> --- /dev/null
>> +++ b/OvmfPkg/Library/XenConsoleSerialPortLib/XenConsoleSerialPortLib.inf
>> @@ -0,0 +1,34 @@
>> +#/** @file
>> +#
>> +#  Component description file for XenConsoleSerialPortLib module
>> +#
>> +#  Copyright (c) 2015, Linaro Ltd. All rights reserved.<BR>
>> +#
>> +#  This program and the accompanying materials
>> +#  are licensed and made available under the terms and conditions of the BSD License
>> +#  which accompanies this distribution.  The full text of the license may be found at
>> +#  http://opensource.org/licenses/bsd-license.php
>> +#
>> +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
>> +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>> +#
>> +#**/
>> +
>> +[Defines]
>> +  INF_VERSION                    = 0x00010005
>> +  BASE_NAME                      = XenConsoleSerialPortLib
>> +  FILE_GUID                      = 401406DD-BCAC-4B91-9F4E-72A7FEBE4762
>> +  MODULE_TYPE                    = BASE
>> +  VERSION_STRING                 = 1.0
>> +  LIBRARY_CLASS                  = SerialPortLib
>> +
>> +[Sources.common]
>> +  XenConsoleSerialPortLib.c
>> +
>> +[LibraryClasses]
>> +  BaseLib
>> +  XenHypercallLib
>> +
>> +[Packages]
>> +  MdePkg/MdePkg.dec
>> +  OvmfPkg/OvmfPkg.dec
>> --
>> 1.8.3.2
>>

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