Re: [win-pv-devel] [PATCH] Add a user mode library wrapper for XENIFACE IOCTLs

[Owen Smith <owen.smith@xxxxxxxxxx>]

> -----Original Message-----
> From: win-pv-devel [mailto:win-pv-devel-bounces@xxxxxxxxxxxxxxxxxxxx] On
> Behalf Of Marek Marczykowski-Górecki
> Sent: 09 July 2018 11:22
> To: win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> Cc: Rafal Wojdyla <omeg@xxxxxxxxxxxxxxxxxxxxxx>; Marek Marczykowski-
> Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
> Subject: [win-pv-devel] [PATCH] Add a user mode library wrapper for XENIFACE
> IOCTLs
> 
> From: Rafal Wojdyla <omeg@xxxxxxxxxxxxxxxxxxxxxx>
> 
> Signed-off-by: Rafal Wojdyla <omeg@xxxxxxxxxxxxxxxxxxxxxx>
> [fix compile warnings, update visual studio files]
> Signed-off-by: Marek Marczykowski-Górecki
> <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
> ---
> This was posted before here:
> https://lists.xenproject.org/archives/html/win-pv-devel/2015-
> 11/msg00014.html
> 
> Back then I've raised a concern about code duplication caused by a
> different API than libxc (having libxenvchan in mind). But two years
> latter it looks like it isn't such a problem. libxenchan is the only
> piece being effectively duplicated (at least in Qubes OS), and
> everything else is really different anyway because of Linux/Windows
> differences. So, I think it isn't an issue.
> 
> Also I've renamed XcEvtchnBindUnbound to XcEvtchnOpenUnbound, as
> requested in review back then.
> 
> This has been tested with vs2017/WDK10 build for Windows 7 64bit, both
> on Windows 7 and Windows 10. The patch assume "Add Windows 7 build
> target" patches applied, but it should be easy to apply without them
> too.
> I've updated vs2015 files too, but don't have tools to test them (it
> isn't possible to download free vs2015 anymore).
> ---
>  include/xencontrol.h                         | 342 ++++++++++
>  src/xencontrol/xencontrol.c                  | 919 
> +++++++++++++++++++++++++++
>  src/xencontrol/xencontrol.rc                 |  24 +
>  src/xencontrol/xencontrol_private.h          |  49 ++
>  vs2015/package/package.vcxproj               |   3 +
>  vs2015/xencontrol/xencontrol.vcxproj         |  67 ++
>  vs2015/xencontrol/xencontrol.vcxproj.filters |  13 +
>  vs2015/xeniface.sln                          |  38 ++
>  vs2017/package/package.vcxproj               |   3 +
>  vs2017/xencontrol/xencontrol.vcxproj         |  67 ++
>  vs2017/xencontrol/xencontrol.vcxproj.filters |  13 +
>  vs2017/xeniface.sln                          |  38 ++
>  12 files changed, 1576 insertions(+)
>  create mode 100644 include/xencontrol.h
>  create mode 100644 src/xencontrol/xencontrol.c
>  create mode 100644 src/xencontrol/xencontrol.rc
>  create mode 100644 src/xencontrol/xencontrol_private.h
>  create mode 100644 vs2015/xencontrol/xencontrol.vcxproj
>  create mode 100644 vs2015/xencontrol/xencontrol.vcxproj.filters
>  create mode 100644 vs2017/xencontrol/xencontrol.vcxproj
>  create mode 100644 vs2017/xencontrol/xencontrol.vcxproj.filters

[snip]

> +
> +DWORD
> +XcOpen(
> +    IN  XENCONTROL_LOGGER *Logger,
> +    OUT PXENCONTROL_CONTEXT *Xc
> +    )
> +{
> +    HDEVINFO DevInfo;
> +    SP_DEVICE_INTERFACE_DATA InterfaceData;
> +    SP_DEVICE_INTERFACE_DETAIL_DATA *DetailData = NULL;
> +    DWORD BufferSize;
> +    PXENCONTROL_CONTEXT Context;
> +
> +    Context = malloc(sizeof(*Context));
> +    if (Context == NULL)
> +        return ERROR_NOT_ENOUGH_MEMORY;
> +
> +    Context->Logger = Logger;
> +    Context->LogLevel = XLL_INFO;
> +    Context->RequestId = 1;
> +    InitializeListHead(&Context->RequestList);
> +    InitializeCriticalSection(&Context->RequestListLock);
> +
> +    DevInfo = SetupDiGetClassDevs(&GUID_INTERFACE_XENIFACE, 0, NULL,
> DIGCF_PRESENT | DIGCF_DEVICEINTERFACE);
> +    if (DevInfo == INVALID_HANDLE_VALUE) {
> +        _Log(Logger, XLL_ERROR, Context->LogLevel, __FUNCTION__,
> +             L"XENIFACE device class doesn't exist");
> +        goto fail;
> +    }
> +
> +    InterfaceData.cbSize = sizeof(InterfaceData);
> +    if (!SetupDiEnumDeviceInterfaces(DevInfo, NULL,
> &GUID_INTERFACE_XENIFACE, 0, &InterfaceData)) {
> +        _Log(Logger, XLL_ERROR, Context->LogLevel, __FUNCTION__,
> +             L"Failed to enumerate XENIFACE devices");
> +        goto fail;
> +    }
> +
> +    SetupDiGetDeviceInterfaceDetail(DevInfo, &InterfaceData, NULL, 0,
> &BufferSize, NULL);
> +    if (GetLastError() != ERROR_INSUFFICIENT_BUFFER) {
> +        _Log(Logger, XLL_ERROR, Context->LogLevel, __FUNCTION__,
> +             L"Failed to get buffer size for device details");
> +        goto fail;
> +    }
> +
> +    // Using 'BufferSize' from failed function call
> +#pragma warning(suppress: 6102)
> +    DetailData = (SP_DEVICE_INTERFACE_DETAIL_DATA *)malloc(BufferSize);
> +    if (!DetailData) {
> +        SetLastError(ERROR_OUTOFMEMORY);
> +        goto fail;
> +    }
> +
> +    DetailData->cbSize = sizeof(SP_DEVICE_INTERFACE_DETAIL_DATA);
> +
> +    if (!SetupDiGetDeviceInterfaceDetail(DevInfo, &InterfaceData, DetailData,
> BufferSize, NULL, NULL)) {
> +        _Log(Logger, XLL_ERROR, Context->LogLevel, __FUNCTION__,
> +             L"Failed to get XENIFACE device path");
> +        goto fail;
> +    }
> +
> +    Context->XenIface = CreateFile(DetailData->DevicePath,
> +                                   FILE_GENERIC_READ | FILE_GENERIC_WRITE,
> +                                   0,
> +                                   NULL,
> +                                   OPEN_EXISTING,
> +                                   FILE_ATTRIBUTE_NORMAL | 
> FILE_FLAG_OVERLAPPED,
> +                                   NULL);

No FILE_SHARE_READ/WRITE options set, preventing creation of other handles to 
xeniface.
This includes the xenagent service (if started after a XenControl user), so no 
power control, etc.

Should it be possible for more than one program to use XenControl at the same 
time?

Owen

> +
> +    if (Context->XenIface == INVALID_HANDLE_VALUE) {
> +        _Log(Logger, XLL_ERROR, Context->LogLevel, __FUNCTION__,
> +             L"Failed to open XENIFACE device, path: %s", 
> DetailData->DevicePath);
> +        goto fail;
> +    }
> +
> +    _Log(Logger, XLL_ERROR, Context->LogLevel, __FUNCTION__,
> +         L"XenIface handle: %p", Context->XenIface);
> +
> +    free(DetailData);
> +    *Xc = Context;
> +    return ERROR_SUCCESS;
> +
> +fail:
> +    _Log(Logger, XLL_ERROR, Context->LogLevel, __FUNCTION__,
> +         L"Error: 0x%x", GetLastError());
> +
> +    free(DetailData);
> +    return GetLastError();
> +}
> +
> +void
> +XcClose(
> +    IN  PXENCONTROL_CONTEXT Xc
> +    )
> +{
> +    CloseHandle(Xc->XenIface);
> +    DeleteCriticalSection(&Xc->RequestListLock);
> +    free(Xc);
> +}
> +

[snip]

> --
> 2.13.6
> 
> 
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