Re: [Xen-devel] [V11 PATCH 00/21]PVH xen: Phase I, Version 11 patches...

[Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>]

On Fri, 30 Aug 2013 18:21:52 +0100
George Dunlap <george.dunlap@xxxxxxxxxxxxx> wrote:

> On 30/08/13 12:02, George Dunlap wrote:
> > On 30/08/13 01:25, Mukesh Rathor wrote:
> >> On Thu, 29 Aug 2013 17:28:57 +0100
> >> George Dunlap <george.dunlap@xxxxxxxxxxxxx> wrote:
> >>
> >>> On 28/08/13 01:37, Mukesh Rathor wrote:
> >>>> On Tue, 27 Aug 2013 18:05:00 +0100
> >>>> George Dunlap <George.Dunlap@xxxxxxxxxxxxx> wrote:
> >>>>
> >>>>> On Sat, Aug 24, 2013 at 1:40 AM, Mukesh Rathor
> >>>>> <mukesh.rathor@xxxxxxxxxx> wrote:
> >>>>>> On Fri, 23 Aug 2013 13:05:08 +0100
......
> >
> > And if I set it to only one vcpu, it gets stuck in an EPT violation
> > loop:
> >
> > (XEN) PVH currently does not support tsc emulation. Setting
> > timer_mode = native
> > (XEN) PVH currently does not support tsc emulation. Setting
> > timer_mode = native
> > (XEN) grant_table.c:577:d0 remote grant table not yet set up[ 
> > 283.823609] device vif3.0 entered promiscuous mode^M
> > [  283.843691] ADDRCONF(NETDEV_UP): vif3.0: link is not ready^M
> > mapping kernel into physical memory
> > about to get started...
> > <G><2>irq.c:375: Dom3 callback via changed to Direct Vector 0xf3
> > (XEN) EPT violation 0x182 (-w-/---), gpa 0x0000003e22df90, mfn 
> > 0xffffffffffffffff, type 4. RIP:0xffffffff817c6ffd
> > RSP:0xffff88003e22df98 (XEN) p2m-ept.c:638:d3 Walking EPT tables
> > for domain 3 gfn 3e22d (XEN) p2m-ept.c:657:d3  epte 1c000008295c6007
> > (XEN) p2m-ept.c:657:d3  epte 1c000008295c5007
> > (XEN) p2m-ept.c:657:d3  epte 1c00000434c38007
> > (XEN) p2m-ept.c:657:d3  epte 0
> > (XEN)  --- GLA 0xffff88003e22df90
> > (XEN) EPT violation 0x182 (-w-/---), gpa 0x0000003e22df88, mfn 
> > 0xffffffffffffffff, type 4. RIP:0xffffffff817c6ffd
> > RSP:0xffff88003e22df98 (XEN) p2m-ept.c:638:d3 Walking EPT tables
> > for domain 3 gfn 3e22d (XEN) p2m-ept.c:657:d3  epte 1c000008295c6007
> > (XEN) p2m-ept.c:657:d3  epte 1c000008295c5007
> > (XEN) p2m-ept.c:657:d3  epte 1c00000434c38007
> > (XEN) p2m-ept.c:657:d3  epte 0
> > (XEN)  --- GLA 0xffff88003e22df88
> > (XEN) EPT violation 0x182 (-w-/---), gpa 0x0000003e22df88, mfn 
> > 0xffffffffffffffff, type 4. RIP:0xffffffff817c6ffd
> > RSP:0xffff88003e22df98 (XEN) p2m-ept.c:638:d3 Walking EPT tables
> > for domain 3 gfn 3e22d (XEN) p2m-ept.c:657:d3  epte 1c000008295c6007
> > (XEN) p2m-ept.c:657:d3  epte 1c000008295c5007
> > (XEN) p2m-ept.c:657:d3  epte 1c00000434c38007
> > (XEN) p2m-ept.c:657:d3  epte 0
> > (XEN)  --- GLA 0xffff88003e22df88
> 
> I took a xentrace of this, and it looks like what happens is this:
> 
> ]  9.403782967 --------x------- d3v0 vmexit exit_reason VMCALL eip 
> ffffffff81001405
> ]  9.403784176 --------x------- d3v0 vmentry cycles 2903
> ]  9.403792751 --------x------- d3v0 vmexit exit_reason VMCALL eip 
> ffffffff81001305
> ]  9.403794945 --------x------- d3v0 vmentry cycles 5263
> ]  9.404782907 --------x------- d3v0 vmexit exit_reason 
> EXTERNAL_INTERRUPT eip ffffffff817c6ff0
>     9.404782907 --------x------- d3v0 intr vec THERMAL_APIC(fa)
>     9.404782907 --------x------- d3v0 intr_window vec 243 src
> 5(vector) intr #
> ]  9.404785283 --------x------- d3v0 vmentry cycles 5703
> ]  9.406630481 --------x------- d3v0 vmexit exit_reason EXCEPTION_NMI 
> eip ffffffff817ca5a5
>     9.406630481 --------x------- inj_exc trap Invalid Op ec ffffffff
>     9.406630481 --------x------- d3v0 intr_window vec 243 src
> 5(vector) intr 6
> ]  9.406634957 --------x------- d3v0 vmentry cycles 10741 !
> hvm_generic_postprocess: Strange, exit 0(EXCEPTION_NMI) missing a
> handler ]  9.406636249 --------x------- d3v0 vmexit exit_reason
> EXCEPTION_NMI eip ffffffff817ca655
>     9.406636249 --------x------- inj_exc trap Invalid Op ec ffffffff
>     9.406636249 --------x------- d3v0 intr_window vec 243 src
> 5(vector) intr 6
> ]  9.406637659 --------x------- d3v0 vmentry cycles 3382
> ]  9.406638483 --------x------- d3v0 vmexit exit_reason EXCEPTION_NMI 
> eip ffffffff817ca655
>     9.406638483 --------x------- inj_exc trap Invalid Op ec ffffffff
>     9.406638483 --------x------- d3v0 intr_window vec 243 src
> 5(vector) intr 6
> ]  9.406639793 --------x------- d3v0 vmentry cycles 3143
> 
> 
> Note the "Invalid Op" that's being delivered, at address 
> ffffffff817ca5a5.  Here is a disassembly of that region:
> 
> ffffffff817ca5a0 <do_page_fault>:
> ffffffff817ca5a0:       55                      push   %rbp
> ffffffff817ca5a1:       48 89 e5                mov    %rsp,%rbp
> ffffffff817ca5a4:       e8 47 fb ff ff          callq
> ffffffff817ca0f0 <__do_page_fault>
> ffffffff817ca5a9:       5d                      pop    %rbp
> ffffffff817ca5aa:       c3                      retq
> ffffffff817ca5ab:       90                      nop
> 
> If you'll notice, ffffffff817ca5a5 is actually in the middle of an 
> instruction; it's no surprise that it's an invalid one.  The next two 
> eips for illegal instructions are at ffffffff817ca655:
> 
> ffffffff817ca650 <notify_die>:
> ffffffff817ca650:       55                      push   %rbp
> ffffffff817ca651:       48 89 e5                mov    %rsp,%rbp
> ffffffff817ca654:       48 83 ec 20             sub    $0x20,%rsp
> ffffffff817ca658:       48 89 55 e0             mov %rdx,-0x20(%rbp)
> ffffffff817ca65c:       48 8d 55 e0             lea -0x20(%rbp),%rdx
> ffffffff817ca660:       48 89 75 e8             mov %rsi,-0x18(%rbp)
> ffffffff817ca664:       89 fe                   mov    %edi,%esi
> ffffffff817ca666:       48 c7 c7 10 55 e4 81    mov
> $0xffffffff81e45510,%rdi ffffffff817ca66d:       48 89 4d
> f0             mov %rcx,-0x10(%rbp) ffffffff817ca671:       44 89 45
> f8             mov %r8d,-0x8(%rbp) ffffffff817ca675:       44 89 4d
> fc             mov %r9d,-0x4(%rbp) ffffffff817ca679:       e8 b2 ff
> ff ff          callq ffffffff817ca630 <atomic_notifier_call_chain>
> ffffffff817ca67e:       c9                      leaveq
> ffffffff817ca67f:       c3                      retq
> 
> Again, in the middle of an instruction; and again 5 bytes after the 
> beginning of a function.
> 
> It looks, from the rest of it, like it keeps looping on illegal op
> exits in the fault handlers until it runs out of stack space and hits
> an EPT fault.
> 
> The first question to ask, of course, is whether the disassembly is 
> valid; I think it is, because I looked up the RIP of 5-6 vmexits
> before this one, and they seem to match (e.g., CPUID exits are at an
> RIP that the disassembly says is a cpuid instruction).
> 
> Any ideas what might be causing it to end up in the middle of 
> instructions while handling exits?
> 
> I should repeat, this is your tree + the tools patch, without any 
> changes.  (My port actually does the same thing, which is reassuring
> I guess...)

The RIP totally doesn't makes sense, and 90% of the time, I've found
make mrproper to completely clean it up and starting again, will give
you better info. 

I think it might be better to have one tree. So, konrad has refreshed
the tree pvh.v9, I'm taking that and adding whatever patches, make it
work, and then put it externally. So you and I will then both be looking
at exact same linux. Monday is holiday here, so most likely the external
tree would be Tues/Wed, gotta go thru admin hoops here to set it up.

thanks
mukesh



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