[Xen-ia64-devel] Question to strange xen panic

[Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxxxxxxx>]

Hi,

while playing with my mini-os I got the following Xen-panic:

ia64_fault, vector=0x18, ifa=0xf000000016d23db0, iip=0xa000000100003660, 
ipsr=0x0000121208026018, isr=0x0000020000000030
(XEN) General Exception: IA-64 Reserved Register/Field fault (data access).
(XEN) d 0xf000000007d0c080 domid 8
(XEN) vcpu 0xf000000007d48000 vcpu 0
(XEN) 
(XEN) CPU 0
(XEN) psr : 0000121208026018 ifs : 8000000000000690 ip  : [<a000000100003661>]
(XEN) ip is at ???
(XEN) unat: 0000000000000000 pfs : 8000000000000690 rsc : 000000000000000b
(XEN) rnat: 0000000000000000 bsps: e000000007fe0010 pr  : 0000000000000241
(XEN) ldrs: 0000000000880000 ccv : 00000000fffffff3 fpsr: 0009804c8a70033f
(XEN) csd : 0000000000000000 ssd : 0000000000000000
(XEN) b0  : a000000100003660 b6  : a000000100004b80 b7  : a00000010000c410
(XEN) f6  : 10002e000000000000000 f7  : 100038000000000000000
(XEN) f8  : 1003e0000000000000000 f9  : 0fffedffffffff2000000
(XEN) f10 : 0ffdee000000000000000 f11 : 0ffed8000000000000000
(XEN) r1  : a00000010002c020 r2  : 0000000000000020 r3  : 0000000000004000
(XEN) r8  : 0000000000000001 r9  : 000000000bebc200 r10 : 0000000000000064
(XEN) r11 : 0000000000000000 r12 : e000000007fe7ff0 r13 : e000000007ff0250
(XEN) r14 : 0000000000000004 r15 : 8000000007fe7fb0 r16 : 0000000000000000
(XEN) r17 : 00000000000007ff r18 : e000000007fe7fa4 r19 : e000000007fe7f74
(XEN) r20 : 3736353433323130 r21 : 3736353433323130 r22 : e000000007fe7f50
(XEN) r23 : e000000007fe7f80 r24 : 0000000000000007 r25 : 0000000000000000
(XEN) r26 : 0000000000000000 r27 : 0000000000000000 r28 : 000000000000000e
(XEN) r29 : e000000007ff0300 r30 : e000000007ff0460 r31 : 8000000000000893
(XEN) 
(XEN) Call Trace:
(XEN)  [<f00000000409e2c0>] show_stack+0x80/0xa0
(XEN)                                 sp=f000000007d4fc30 bsp=f000000007d48e50
(XEN)  [<f00000000406afd0>] ia64_fault+0x130/0x4f0
(XEN)                                 sp=f000000007d4fe00 bsp=f000000007d48e18
(XEN)  [<f000000004097a80>] ia64_leave_kernel+0x0/0x310
(XEN)                                 sp=f000000007d4fe00 bsp=f000000007d48e18
(XEN) 
(XEN) ****************************************
(XEN) Panic on CPU 0:
(XEN) Fault in Xen.
(XEN) ****************************************

iip points to the instruction:
mov.i ar.pfs=r43
Maybe the current frame is strange, so the trap is OK.
What I don't understand is the panic in xen.
In xen/arch/ia64/xen/ivt.S:
ENTRY(general_exception)
        DBG_FAULT(24)
        mov r16=cr.isr
        mov r31=pr
        ;;
#ifdef XEN
        cmp4.ge p6,p0=0x20,r16
(p6)    br.sptk.many dispatch_privop_fault
#else
        cmp4.eq p6,p0=0,r16
(p6)    br.sptk.many dispatch_illegal_op_fault
#endif
        ;;
        mov r19=24              // fault number
        br.sptk.many dispatch_to_fault_handler
END(general_exception)

Because isr.code == 0x30, it falls through and calls 
dispatch_to_fault_handler() (as far as I understand this ;-)). And 
dispatch_to_fault_handler() leads to the Xen panic.
If I see this right then should not be called a reflection to the domU?
Thanks.

Dietmar.

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