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WHvWriteGpaRange

Writes up to WHV_READ_WRITE_GPA_RANGE_MAX_SIZE bytes to a partition's guest physical address space.

Syntax

// Guest physical address
typedef UINT64 WHV_GUEST_PHYSICAL_ADDRESS;

//
// Maximum data size used by WHvReadGpaRange and WHvWriteGpaRange
//
#define WHV_READ_WRITE_GPA_RANGE_MAX_SIZE 16

typedef enum WHV_CACHE_TYPE {
    WHvCacheTypeUncached         = 0,
    WHvCacheTypeWriteCombining   = 1,
    WHvCacheTypeWriteThrough     = 4,

#if defined(_AMD64_)
    WHvCacheTypeWriteProtected   = 5,
#endif

    WHvCacheTypeWriteBack        = 6
} WHV_CACHE_TYPE;

typedef union WHV_INPUT_VTL
{
    UINT8 AsUINT8;
    struct
    {
        UINT8 TargetVtl    : 4;
        UINT8 UseTargetVtl : 1;
        UINT8 Reserved     : 3;
    };
} WHV_INPUT_VTL;

//
// Control flags used by WHvReadGpaRange and WHvWriteGpaRange
//
typedef union WHV_ACCESS_GPA_CONTROLS
{
    UINT64 AsUINT64;
    struct
    {
        //
        // Cache type for access
        //
        WHV_CACHE_TYPE CacheType;

        //
        // VTL whose GPA is to be accessed
        //
        WHV_INPUT_VTL InputVtl;
        UINT8 Reserved;
        UINT16 Reserved1;
    };
} WHV_ACCESS_GPA_CONTROLS;

HRESULT
WINAPI
WHvWriteGpaRange(
    _In_ WHV_PARTITION_HANDLE Partition,
    _In_ UINT32 VpIndex,
    _In_ WHV_GUEST_PHYSICAL_ADDRESS GuestAddress,
    _In_ WHV_ACCESS_GPA_CONTROLS Controls,
    _In_reads_bytes_(DataSizeInBytes) const VOID* Data,
    _In_ UINT32 DataSizeInBytes
    );

Parameters

Partition

Handle to the partition object.

VpIndex

Specifies the index of the virtual processor in whose context the access is performed.

GuestAddress

Specifies the guest physical address at which the write begins.

Controls

Specifies the cache type and target VTL for the access, as a WHV_ACCESS_GPA_CONTROLS value.

Data

Specifies the bytes to write to the guest physical address range.

DataSizeInBytes

Specifies the number of bytes to write. This value must be greater than zero and no larger than WHV_READ_WRITE_GPA_RANGE_MAX_SIZE.

Return Value

If the function succeeds, the return value is S_OK.

The function can return the following failure codes:

  • E_INVALIDARG — DataSizeInBytes is greater than WHV_READ_WRITE_GPA_RANGE_MAX_SIZE, the CacheType in Controls is not a valid cache type, the InputVtl in Controls does not refer to the current VTL, or a reserved field in Controls is set.
  • E_ACCESSDENIED — the guest physical address range is not mapped or the access is otherwise not permitted.

Remarks

The WHvWriteGpaRange function writes up to WHV_READ_WRITE_GPA_RANGE_MAX_SIZE (16) bytes to guest physical memory in the context of a virtual processor. This limited access size makes the function suitable for emulating instruction operands rather than bulk memory transfer. For larger transfers, back the guest physical memory with a host mapping created by WHvMapGpaRange or WHvMapGpaRange2 and access it directly.

Because the write is performed in the context of the virtual processor identified by VpIndex, it observes the memory access semantics that apply to that processor, including the cache type and VTL specified in Controls. If the targeted page is not yet resident, the function faults it in and retries the access.

Requirements

Requirement Value
Minimum supported Windows Windows 10, version 20H2 (x64); Windows 11, version 24H2, build 26100.3915 (Arm64)
Header WinHvPlatform.h
Library WinHvPlatform.lib
DLL WinHvPlatform.dll
Architecture x64, Arm64

See also

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