Re: [Xen-devel] Native hypercall basics using int 82

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

We relocate the Xen CPUID info when we emulate Hyper-V. You need to scan for the Xen signature — starting at 0x40000000 and then every 0x100 up to 0x40001000. If you find the signature then you have found the contiguous range of Xen CPUID leaves. I should fix xen-detect.c to do this scan.

 -- Keir

On 16/12/2008 10:33, "hnrkssn hnrkssn" <hnrkssn@xxxxxxxxx> wrote:

> I have already tried the CPUID approach used in xen-detect.c
> When I read the info from leaf 0x40000001, it says "Microsoft Hv" when I run it on Citrix XenServer Express Edition.
> I thought "Microsoft Hv" was supposed to identify Hyper-V?
>
> So I have to try another method. 
> Can anybody give me some hints on my assembler example in the initial post for making a hypercall?
>
> ---
> 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
>   {
>     MOV EAX, phypercall;
>     INT 82;
>   }
>
>   Buffer[255] = '\0';
>   
>   Cprintf("Buf: %s\r\n", Buffer);
>
>
>
> Best Regards, 
> David
>
> On Tue, Dec 16, 2008 at 9:47 AM, Keir Fraser <keir.fraser@xxxxxxxxxxxxx> wrote:
> > On 16/12/2008 08:39, "hnrkssn hnrkssn" <hnrkssn@xxxxxxxxx> wrote:
> >
> > > 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.
> >
> > See tools/misc/xen-detect.c for a nice approach that even works from user
> > space.
> >
> >  -- Keir



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