Re: [Xen-devel] [PATCH v1 17/21] Ovmf/Xen: add Xen PV console SerialPortLib driver

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

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@xxxxxxxxxx>
> ---
>  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?


> +}
> 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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