RE: [Xen-ia64-devel] [PATCH] Xen panics when domvti is destroyed

[Kouya SHIMURA <kouya@xxxxxxxxxxxxxx>]

Hi Anthony,

Thanks for your comment.
If it is safe that vmx_reliquish_vcpu_resouces(vcpu) is called
before the vcpu is booted, your modification looks better.

I'm afraid of the race condition between vmx_final_setup_guest()
and vmx_relinquish_vcpu_resources(). 
Supposing such a condition, we might have to use some lock in order to
prevent memory leak. How do you think?

Thanks,
Kouya

Xu, Anthony writes:
 > Hi Kouya,
 > 
 > Good catch!
 > 
 > I think the root cause is, when VTI-domain is destroyed, vti-flag in vcpu 
 > structure is not set while vti-flag in domain structure is set, so XEN think 
 > of this vcpu as domU vcpu by mistake, then issue appears,
 > 
 > Yes, your patch can fix this issue, but seems it may incur memory leak. 
 > Maybe following small modification is needed.
 > 
 > Anthony
 > 
 > --- a/xen/arch/ia64/xen/domain.c     Sun Oct 08 18:55:12 2006 -0600
 > +++ b/xen/arch/ia64/xen/domain.c     Tue Oct 10 19:06:44 2006 +0900
 > @@ -341,9 +341,11 @@ void relinquish_vcpu_resources(struct vc
 >  
 >  void free_vcpu_struct(struct vcpu *v)
 >  {
 > -    if (VMX_DOMAIN(v))
 > -            vmx_relinquish_vcpu_resources(v);
 > -    else
 > +    if (v->domain->arch.is_vti) {
 > +            vmx_relinquish_vcpu_resources(v);
 > +    } else
 >              relinquish_vcpu_resources(v);
 >  
 >      free_xenheap_pages(v, KERNEL_STACK_SIZE_ORDER);
 > 
 > 
 > 
 > >-----Original Message-----
 > >From: xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx
 > >[mailto:xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Kouya 
 > >SHIMURA
 > >Sent: 2006年10月10日 18:31
 > >To: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
 > >Subject: [Xen-ia64-devel] [PATCH] Xen panics when domvti is destroyed
 > >
 > >Hi,
 > >
 > >I got the following panic message when I destroyed a domvti which has
 > >2 vcpus and 2nd vcpu is not booted yet. This panic occurs from cset 11745.
 > >Attached patch fixes it.
 > >
 > >(XEN) ia64_fault, vector=0x1e, ifa=0xf00000000414802a, 
 > >iip=0xf000000004030ef0, i
 > >psr=0x0000121008226018, isr=0x00000a0600000000
 > >(XEN) Unaligned Reference.
 > >(XEN) d 0xf000000007d5c080 domid 0
 > >(XEN) vcpu 0xf000000007d30000 vcpu 0
 > >(XEN)
 > >(XEN) CPU 1
 > >(XEN) psr : 0000121008226018 ifs : 800000000000040b ip  : 
 > >[<f000000004030ef1>]
 > >(XEN) ip is at free_domheap_pages+0x131/0x7f0
 > >(XEN) unat: 0000000000000000 pfs : 0000000000000206 rsc : 0000000000000003
 > >(XEN) rnat: 0000000000000206 bsps: 0000000000000003 pr  : 0000000005569aab
 > >(XEN) ldrs: 0000000000000000 ccv : 0000000000000000 fpsr: 0009804c0270033f
 > >(XEN) csd : 0000000000000000 ssd : 0000000000000000
 > >(XEN) b0  : f000000004074930 b6  : f000000004034130 b7  : a000000100067a90
 > >(XEN) f6  : 1003e00000000000670a4 f7  : 1003ecccccccccccccccd
 > >(XEN) f8  : 1003e00000000000c2d06 f9  : 10001c000000000000000
 > >(XEN) f10 : 100099c1aaaaaaa0e9000 f11 : 1003e00000000000004e0
 > >(XEN) r1  : f000000004316d10 r2  : 0000000000000000 r3  : f000000007d37fe8
 > >(XEN) r8  : 0000000000000040 r9  : 0000000000000000 r10 : 0000000000000000
 > >(XEN) r11 : 0009804c0270033f r12 : f000000007d37930 r13 : f000000007d30000
 > >(XEN) r14 : 0000000000000000 r15 : 000000019c290000 r16 : 0000000000000001
 > >(XEN) r17 : f000000007ff7510 r18 : f000000007a0eb00 r19 : f000000007ff7500
 > >(XEN) r20 : f000000007a0eb08 r21 : f00000000414803a r22 : f00000000414802a
 > >(XEN) r23 : f0000000040e8200 r24 : 0000001008226018 r25 : f00000000411f420
 > >(XEN) r26 : f000000004119300 r27 : 0000000000000000 r28 : fffffffffff00001
 > >(XEN) r29 : 0000000080000000 r30 : 0000000000000001 r31 : f00000000414802a
 > >(XEN)
 > >(XEN) Call Trace:
 > >(XEN)  [<f000000004099b40>] show_stack+0x80/0xa0
 > >(XEN)                                 sp=f000000007d37560 
 > >bsp=f000000007d310d0
 > >(XEN)  [<f00000000406b050>] ia64_fault+0x280/0x670
 > >(XEN)                                 sp=f000000007d37730 
 > >bsp=f000000007d31098
 > >(XEN)  [<f000000004096b00>] ia64_leave_kernel+0x0/0x310
 > >(XEN)                                 sp=f000000007d37730 
 > >bsp=f000000007d31098
 > >(XEN)  [<f000000004030ef0>] free_domheap_pages+0x130/0x7f0
 > >(XEN)                                 sp=f000000007d37930 
 > >bsp=f000000007d31040
 > >(XEN)  [<f000000004074930>] pervcpu_vhpt_free+0x30/0x50
 > >(XEN)                                 sp=f000000007d37930 
 > >bsp=f000000007d31020
 > >(XEN)  [<f0000000040505d0>] relinquish_vcpu_resources+0x50/0xf0
 > >(XEN)                                 sp=f000000007d37930 
 > >bsp=f000000007d30ff0
 > >(XEN)  [<f000000004050700>] free_vcpu_struct+0x90/0xc0
 > >(XEN)                                 sp=f000000007d37930 
 > >bsp=f000000007d30fd0
 > >(XEN)  [<f00000000401e380>] free_domain+0x50/0x90
 > >(XEN)                                 sp=f000000007d37930 
 > >bsp=f000000007d30fa0
 > >(XEN)  [<f00000000401f100>] domain_destroy+0x2e0/0x320
 > >(XEN)                                 sp=f000000007d37930 
 > >bsp=f000000007d30f80
 > >(XEN)  [<f000000004031190>] free_domheap_pages+0x3d0/0x7f0
 > >(XEN)                                 sp=f000000007d37940 
 > >bsp=f000000007d30f40
 > >(XEN)  [<f0000000040627d0>] zap_domain_page_one+0x360/0x4d0
 > >(XEN)                                 sp=f000000007d37940 
 > >bsp=f000000007d30ef8
 > >(XEN)  [<f000000004062980>] dom0vp_zap_physmap+0x40/0x70
 > >(XEN)                                 sp=f000000007d37940 
 > >bsp=f000000007d30ec8
 > >(XEN)  [<f00000000404f2f0>] do_dom0vp_op+0x250/0x300
 > >(XEN)                                 sp=f000000007d37940 
 > >bsp=f000000007d30e80
 > >(XEN)  [<f00000000405bed0>] ia64_hypercall+0x7b0/0xdc0
 > >(XEN)                                 sp=f000000007d37940 
 > >bsp=f000000007d30e20
 > >(XEN)  [<f00000000406b590>] ia64_handle_break+0x150/0x2e0
 > >(XEN)                                 sp=f000000007d37df0 
 > >bsp=f000000007d30de0
 > >(XEN)  [<f000000004096b00>] ia64_leave_kernel+0x0/0x310
 > >(XEN)                                 sp=f000000007d37e00 
 > >bsp=f000000007d30de0
 > >(XEN)
 > >(XEN) ****************************************
 > >(XEN) Panic on CPU 1:
 > >(XEN) Fault in Xen.
 > >(XEN) ****************************************
 > >
 > >Signed-off-by: Kouya Shimura <kouya@xxxxxxxxxxxxxx>


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