[Xen-devel] Native hypercall basics using int 82

["hnrkssn hnrkssn" <hnrkssn@xxxxxxxxx>]

Hi, 

I'm trying to detect if I'm running as a guest in XEN hypervisor using a simple hypercall like __HYPERVISOR_xen_version with the XENVER_extraversion option.
I cannot use any of the API functions for this so I'm trying to setup the required registers and call int 82 myself. 
This is what I do and unfortunately, it generates an exception 0xd when executing INT 82. 

Reading the source, I think I've figured out that I should put my arguments in a hypercall struct shown below. I might be wrong then.

Thanks in advance
David

---
char buffer[256];
HYPERCALL hypercall;
PHYPERCALL phypercall = &hypercall;

hypercall.op     = 17;                       // xen_version
hypercall.arg[0] = (unsigned long) 1; // xen_extra_version
hypercall.arg[1] = (unsigned long) Buffer;

memset(Buffer, 0, sizeof(Buffer));

_asm
  {
    PUSH EDI;
    PUSH ESI;
    PUSH EDX;
    PUSH ECX;
    PUSH EBX;
    PUSH EAX;
    
    
    MOV EAX, phypercall;
    INT 82;
    
    POP EAX;
    POP EBX;
    POP ECX
    POP EDX;
    POP ESI;
    POP EDI;
  }

  BufferA[255] = '\0';
  
  Cprintf("Buf: %s\r\n", Buffer);
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