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include vmm.inc
 
mov     eax, Interrupt          ; interrupt number for fault
mov     esi, OFFSET32 FaultProc ; points to a fault handler
VMMcall Hook_VMM_Fault
 
jc      not_installed           ; carry set if not installed
mov     [Previous], esi         ; points to previous fault handler (if any)
 
The Hook_VMM_Fault service installs a fault handler procedure for the VMM.
Virtual devices typically install fault handlers while processing the
Sys_Critical_Init control message to handle faults, such as general
protection faults, that the VMM's own fault handlers cannot handle. The VMM
installs its fault handlers after the Sys_Critical_Init control message.
Virtual devices install fault handlers after Sys_Critical_Init to handle
faults before the fault is passed to the VMM's fault handlers.
 
Parameter  Description
────────────────────────────────────────────────────────────────────────────
 
Interrupt  Specifies the number of the interrupt for which install the fault
           handler. The interrupt number cannot be 02h and must not be
           greater than 4Fh.
 
FaultProc  Points to the fault handler to install. See the Comments section
           for more information about this procedure.
 
Return Value
 
If the carry flag is clear, the ESI register contains the address of the
previous fault handler. The register contains zero if there was no previous
handler.
 
If the carry flag is set, the specified fault number is not valid and the
handler is not installed.
 
Comments
 
A virtual device can install a fault handler while processing the
Sys_Critical_Init message or at a later time. Any fault handler a virtual
device may install while processing the message receives a fault only after
the VMM's own fault handlers have had a chance to process the fault.
 
The system disables interrupts and calls the fault handler as follows:
 
mov     ebx, VM                 ; current VM handle
mov     ebp, OFFSET32 stkfrm    ; points to VMM re-entrant stack frame
call    [FaultProc]
 
The VM parameter is a handle identifying the current virtual machine, and
the stkfrm parameter points to the VMM re-entrant fault stack frame.
 
The fault handler may call asynchronous services only.
 
If the fault handler does not process the fault, it should pass the fault to
the previous fault handler (if any), making sure that all registers are
preserved (not just the registers containing input parameters).
 
If the fault handler processes the fault or if there is no previous fault
handler, the handler should return without chaining by executing a near ret
instruction (not an iret instruction).
 
The fault handler can modify EAX, EBX, ECX, EDX, ESI, and EDI.
 
Do not use this service to install a fault handler for the Non-Maskable
Interrupt (NMI). Instead, a virtual device must use the
Get_NMI_Handler_Addr and Set_NMI_Handler_Addr services.
 
Do not use this service to install handlers for hardware interrupts.
Instead, a virtual device must use virtual PIC device services.
 
Uses
 
ESI, Flags
 
See Also
 
Hook_PM_Fault, Hook_V86_Fault
 
 
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