Re: [Xen-ia64-devel] [PATCH] Fix vti guests broken issue.

[Isaku Yamahata <yamahata@xxxxxxxxxxxxx>]

On Fri, Nov 07, 2008 at 11:33:43AM +0800, Zhang, Xiantao wrote:
> But another thing to meation, why mfn_valid with invalid parameter will incur 
> the fault?  Seems mfn_valid has something wrong, I have no enough time to 
> find the cause.  Is it a known issue ? Or mfn_valid has some limitation ? 

mfn_valid() with invalid parameter shouldn't cause panic.
It may cause tlb miss fault, but the fault should be handled specially
by frametable_fault in ivt.S and should be recovered resulting
in mfn_valid() returning false.

I agree with you that there's something wrong in mfn_valid()
I haven't aware of the issue.

thanks,

> Thanks
> Xiantao
> 
> Zhang, Xiantao wrote:
> > Yes. Should be addressed.
> > 
> > -----Original Message-----
> > From: Isaku Yamahata [mailto:yamahata@xxxxxxxxxxxxx]
> > Sent: Friday, November 07, 2008 11:03 AM
> > To: Zhang, Xiantao
> > Cc: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> > Subject: Re: [Xen-ia64-devel] [PATCH] Fix vti guests broken issue.
> > 
> > Oh, my bad. Thank you for debugging.
> > I applied and pushed out.
> > Does this fixed the issue you repoted?
> > 
> > thanks,
> > 
> > On Fri, Nov 07, 2008 at 10:42:57AM +0800, Zhang, Xiantao wrote:
> >> PATCH : Fix vti guests broken issue.
> >> mfn_valid should use machine physical pfn, not guest physical pfn.
> >> 
> >> Sign-off-by: Xiantao Zhang <xiantao.zhang@xxxxxxxxx>
> >> 
> >> 
> >> diff -r f6795589ef82 xen/arch/ia64/vmx/vtlb.c
> >> --- a/xen/arch/ia64/vmx/vtlb.c     Thu Nov 06 12:14:57 2008 +0900
> >> +++ b/xen/arch/ia64/vmx/vtlb.c     Fri Nov 07 10:35:11 2008 +0800
> >> @@ -522,7 +522,7 @@ static u64 translate_phy_pte(VCPU *v, u6
> >>       * which is required by vga acceleration since qemu maps shared
> >>       * vram buffer with WB.
> >>       */
> >> -    if (mfn_valid(pte_pfn(__pte(pte))) && phy_pte.ma !=
> >> VA_MATTR_NATPAGE) +    if (mfn_valid(pte_pfn(__pte(maddr))) &&
> >>          phy_pte.ma != VA_MATTR_NATPAGE) phy_pte.ma = VA_MATTR_WB;
> >> 
> >>      maddr = ((maddr & _PAGE_PPN_MASK) & PAGE_MASK) | (paddr &
> >> ~PAGE_MASK); 
> > 
> >> _______________________________________________
> >> Xen-ia64-devel mailing list
> >> Xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> >> http://lists.xensource.com/xen-ia64-devel
> 
> 

-- 
yamahata

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