Re: [Xen-ia64-devel] vti panic on thash

[Isaku Yamahata <yamahata@xxxxxxxxxxxxx>]

On Fri, Jan 18, 2008 at 01:15:05PM +0900, Isaku Yamahata wrote:
> On Fri, Jan 18, 2008 at 04:26:23AM +0100, Tristan Gingold wrote:
> > Hi,
> > 
> > I got a very strange error:
> > (XEN) $$$$$ PANIC in domain 2 (k6=0xf0000000079e8000): unknown cause 
> > -2145806064, iip: ffffffff801c6710, ipsr: 501008826030
> > (XEN) d 0xf000000004108080 domid 2
> > (XEN) vcpu 0xf0000000079e8000 vcpu 0
> > (XEN) 
> > (XEN) CPU 0
> > (XEN) psr : 0000501008826030 ifs : 8000000000000103 ip  : 
> > [<ffffffff801c6710>]
> > (XEN) ip is at ???
> > (XEN) unat: 0000000000000000 pfs : 0000000000000287 rsc : 0000000000000000
> > (XEN) rnat: 0000000000000000 bsps: fffff80226a521e8 pr  : 00000000000254c3
> > (XEN) ldrs: 0000000001600000 ccv : 000000008281e8c0 fpsr: 0009804c0274433f
> > (XEN) csd : 0000000000000000 ssd : 0000000000000000
> > (XEN) b0  : ffffffff80199910 b6  : ffffffff801998b0 b7  : ffffffff802d8480
> > (XEN) f6  : 1003e0000000000000037 f7  : 1003e0000000000000040
> > (XEN) f8  : 1003e0000000000000dc0 f9  : 1003e0000000000004000
> > (XEN) f10 : 1003e0000000000000002 f11 : 1003e0000000000002000
> > (XEN) r1  : ffffffff82398000 r2  : ffffffff820488e8 r3  : 0000000000000000
> > 
> > 
> > This is caused (!) by a thash when pta.vf=1
> 
> -2145806064 = 0xffffffff80199910 = b0 value.
> It seems arch_vmx_struct::cause was overwritten somewhere
> in virtualization fault path.

vmx_asm_thash seems to be the culprit.

GLOBAL_ENTRY(vmx_asm_thash)
...
    mov r24=b0                  // save b0
...
    ld8 r25=[r27]               // get vcpu->arch.arch_vmx.vrr[r23]'s
value
...
    // Fall-back to C if VF (long format) is set
    tbit.nz p6,p0=r17,8
   (p6) br.cond.dpnt.many vmx_virtualization_fault_back

The use of r24 and r25 overwrites the cause. 
Probably other register should be used.

-- 
yamahata

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