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FN_VMB_CHANNEL_MAP_GPADL callback function (vmbuskernelmodeclientlibapi.h)

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The VmbChannelMapGpadl function maps a client-side buffer into server-side physical address space by using a Guest Physical Address Descriptor List (GPADL) number.

Syntax

FN_VMB_CHANNEL_MAP_GPADL FnVmbChannelMapGpadl;

NTSTATUS FnVmbChannelMapGpadl(
  VMBCHANNEL Channel,
  UINT32 Flags,
  UINT32 GpadlHandle,
  PMDL *Mdl
)
{...}

Parameters

Channel

A handle for a channel.

Flags

Flags. The possible flag values are:

Value Meaning
VMBUS_CHANNEL_GPADL_FLAG_READ_ONLY
 Map with read-only access.
 

If this flag value is not set, the function tries to map the GPADL for write access. If the GPADL was not created with write access, this mapping attempt fails. The caller is not prevented from writing to the buffer if this flag is set. This scheme is used to improve the performance of live migration and snapshotting.

GpadlHandle

The GPADL handle of the GPADL to map.

Mdl

A pointer to a MDL describing the client buffer. This buffer is only mapped into physical address space. The caller must take additional steps to map it into virtual address space.

Return value

Returns STATUS_SUCCESS if the operation succeeds, or an appropriate NTSTATUS error code otherwise.

Remarks

The GPADL must have been pre-established by the client, for instance, by using the VmbChannelCreateGpadlFromBuffer function.

Only a single mapping may exist for any given GPADL at a time.

You must pair calls to this function with calls to the VmbChannelUnmapGpadl function.

Important

This function is called through the VMBus Kernel Mode Client Library (KMCL) interface, provided by the Vmbkmcl.sys bus driver. This is a server-only function accessed from the KMCL_SERVER_ONLY_METHODS structure.

For more information, see the Remarks section of KMCL_SERVER_ONLY_METHODS.

Requirements

Requirement Value
Minimum supported client Windows 10, version 1803
Header vmbuskernelmodeclientlibapi.h

See also

VmbChannelCreateGpadlFromBuffer

VmbChannelUnmapGpadl