Re: [Xen-ia64-devel] Enabling hypercalls from VT-i domain

[Doi.Tsunehisa@xxxxxxxxxxxxxx]

Hi Tristan,

  Thank you for your comment.

You (Tristan.Gingold) said:
> Le Mercredi 02 Aot 2006 12:34, DOI Tsunehisa a crit :
>> Hi all,
>>
>>   My name is Tsunehisa Doi.
>>
>>   We are porting Steven Smith's para drivers for full-VM to IPF.
>> In the xen-unstable.hg (cs: 10883-10885), it's enabling the hypercall
>> from HVM domain. Thus, I will post the enabling patch for IPF. This
>> patch includes:
>>
>>   + cleanup the hypercall handling code for VT-i domain
>>     - delete the dead code in vmx_hypercall.c and vmx_ivt.S
>>     - the code is not used now, I think.
>>       * It's called with `break 0x1100' instruction. (current 0x1000)
>>       * The hypercall table for VT-i domain doesn't match the
>>         hypercall number.
>>       * The register used for hypercall are different with current
>>         version. (r16-r20 vs. r2,r4-r18)
>>   + enabling hypercalls from VT-i domain
>>     - modify the checker to permit hypercalls from VT-i domain.
>>
>> Thanks,
>> - Tsunehisa Doi
> Hi and welcome!
> 
> diff -r aafdb9899c41 -r e8de7b1474c0 xen/arch/ia64/xen/hypercall.c
> --- a/xen/arch/ia64/xen/hypercall.c     Wed Aug 02 17:48:27 2006 +0900
> +++ b/xen/arch/ia64/xen/hypercall.c     Wed Aug 02 17:52:43 2006 +0900
> @@ -319,7 +319,7 @@ ia64_hypercall (struct pt_regs *regs)
>  
>         /* Hypercalls are only allowed by kernel.
>            Kernel checks memory accesses.  */
> -       if (privlvl != 2) {
> +       if ((regs->cr_ipsr & IA64_PSR_VM) ? (privlvl != 0) : (privlvl != 2)) {
>             /* FIXME: Return a better error value ?
>                Reflection ? Illegal operation ?  */
>             regs->r8 = -1;
> 
> You'd better to use the VMX_DOMAIN macro here.

  I agree. I should use the VMX_DOMAIN macro except for '(regs->.. 
IA64_PSR_VM)'.
I'll modify it.

> I think you'd better not to call ia64_hypercall from VTi side if cpl != 0.

  I worry about this point. The ia64_hypercall is called from ia64_handle_break
without cpl != 2 checking, thus it's checked a privilege level of the caller for
para-domain, I think. I believe that the both codes should be symmetrical.

  What do you think about this point ?

Thanks,
-- Tsunehisa Doi

_______________________________________________
Xen-ia64-devel mailing list
Xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-ia64-devel