Re: [Xen-devel] Fix VGA logdirty related display freezes with altp2m

[Tamas K Lengyel <tamas.k.lengyel@xxxxxxxxx>]

On Thu, Oct 18, 2018 at 3:12 PM Razvan Cojocaru
<rcojocaru@xxxxxxxxxxxxxxx> wrote:
>
> On 10/18/18 11:08 PM, Tamas K Lengyel wrote:
> > On Thu, Oct 18, 2018 at 4:09 AM Razvan Cojocaru
> > <rcojocaru@xxxxxxxxxxxxxxx> wrote:
> >>
> >> Hello,
> >>
> >> This series aims to prevent the display from freezing when
> >> enabling altp2m and switching to a new view (and assorted problems
> >> when resizing the display).
> >>
> >> The first patch propagates ept.ad changes to all active altp2ms,
> >> and the second one allocates a new logdirty rangeset for each
> >> new altp2m, and propagates (under lock) changes to all p2ms.
> >>
> >> The first patch is the same as:
> >> [PATCH V4] x86/altp2m: propagate ept.ad changes to all active altp2ms
> >> but as it is now required for the second one to apply cleanly, it
> >> has been resent as part of this series.
> >>
> >> [PATCH 1/2] x86/altp2m: propagate ept.ad changes to all active altp2ms
> >> [PATCH 2/2] x86/altp2m: fix display frozen when switching to a new
> >
> > Hi Razvan,
> > I would be happy to give this a spin, can you push it as a git branch 
> > somewhere?
>
> Sure, here you go:
>
> https://github.com/razvan-cojocaru/xen/tree/altp2m-logdirty-take1

I ran into this crash when my config incorrectly pointed to a
non-valid disk location:

(XEN) Assertion 'p2m->sync.logdirty_ranges' failed at p2m-ept.c:1475
(XEN) ----[ Xen-4.12-unstable  x86_64  debug=y   Not tainted ]----
(XEN) CPU:    4
(XEN) RIP:    e008:[<ffff82d08033f40c>] p2m_uninit_altp2m_ept+0x29/0x2b
(XEN) RFLAGS: 0000000000010246   CONTEXT: hypervisor
(XEN) rax: ffff83046d27802c   rbx: ffff8304558dd880   rcx: 0000000000000000
(XEN) rdx: ffff83046d277fff   rsi: 00000000004680c0   rdi: 0000000000000000
(XEN) rbp: ffff83046d277d60   rsp: ffff83046d277d50   r8:  ffff82d0809304a0
(XEN) r9:  0000000000455940   r10: ffff82e008d01000   r11: 0000000000000017
(XEN) r12: ffff8304558dd880   r13: ffff8304558df830   r14: ffff8304558df000
(XEN) r15: fffffffffffffff8   cr0: 000000008005003b   cr4: 00000000003526e0
(XEN) cr3: 000000005da16000   cr2: ffff880456cd6e80
(XEN) fsb: 0000000000000000   gsb: ffff880467f40000   gss: 0000000000000000
(XEN) ds: 002b   es: 002b   fs: 0000   gs: 0000   ss: e010   cs: e008
(XEN) Xen code around <ffff82d08033f40c> (p2m_uninit_altp2m_ept+0x29/0x2b):
(XEN)  00 48 83 c4 08 5b 5d c3 <0f> 0b 55 48 89 e5 41 56 41 55 41 54 53 48 8d 05
(XEN) Xen call trace:
(XEN)    [<ffff82d08033f40c>] p2m_uninit_altp2m_ept+0x29/0x2b
(XEN)    [<ffff82d0803305ab>] p2m.c#p2m_teardown_altp2m+0x36/0x52
(XEN)    [<ffff82d0803331b5>] p2m_final_teardown+0x11/0x28
(XEN)    [<ffff82d08034509c>] paging_final_teardown+0x2e/0x3c
(XEN)    [<ffff82d080276439>] arch_domain_destroy+0x50/0xa1
(XEN)    [<ffff82d08020595c>] domain.c#complete_domain_destroy+0x86/0x159
(XEN)    [<ffff82d080228f4f>] rcupdate.c#rcu_process_callbacks+0xa5/0x1cf
(XEN)    [<ffff82d08023ae6b>] softirq.c#__do_softirq+0x71/0x9a
(XEN)    [<ffff82d08023aede>] do_softirq+0x13/0x15
(XEN)    [<ffff82d080275068>] domain.c#idle_loop+0x63/0xb9
(XEN)
(XEN)
(XEN) ****************************************
(XEN) Panic on CPU 4:
(XEN) Assertion 'p2m->sync.logdirty_ranges' failed at p2m-ept.c:1475
(XEN) ****************************************

With the config fixed it boots but when I run DRAKVUF on the domain I
get the following crash:

(XEN) ----[ Xen-4.12-unstable  x86_64  debug=y   Not tainted ]----
(XEN) CPU:    0
(XEN) RIP:    e008:[<000000007bdb630c>] 000000007bdb630c
(XEN) RFLAGS: 0000000000010282   CONTEXT: hypervisor (d0v5)
(XEN) rax: 00000000ee138470   rbx: 0000000000000000   rcx: 000000008000b098
(XEN) rdx: 0000000000000cf8   rsi: 0000000000000000   rdi: 000000046d2ef000
(XEN) rbp: 0000000000000000   rsp: ffff83005da27a10   r8:  0000000000000cf8
(XEN) r9:  0000000000000cf8   r10: ffff83005da27ab8   r11: ffff83005da27a08
(XEN) r12: 0000000000000000   r13: 0000000000000000   r14: 0000000000000065
(XEN) r15: 00000000000005a7   cr0: 0000000080050033   cr4: 0000000000372660
(XEN) cr3: 000000046d2ef000   cr2: 00000000ee138470
(XEN) fsb: 00007fe46d97bbc0   gsb: ffff880467f40000   gss: 0000000000000000
(XEN) ds: 0000   es: 0000   fs: 0000   gs: 0000   ss: e010   cs: e008
(XEN) Xen code around <000000007bdb630c> (000000007bdb630c):
(XEN)  80 74 0b 05 70 84 00 00 <c7> 00 00 00 00 e0 80 3d 7a 34 00 00 00 75 64 48
(XEN) Xen stack trace from rsp=ffff83005da27a10:(XEN) Xen stack trace
from rsp=ffff83005da27a10:
(XEN)    0000000000000000 0000000000000065 ffff83005da27a50 ffff82d08037aafc
(XEN)    00000000fffffffe ffff82d08037ae14 0000000000000000 ffff83005da27a90
(XEN)    0000000000372660 000000046d2ef000 0000000393e91000 ffff82d0809602b0
(XEN)    000000fe00000000 ffff82d0802a3b98 ffffffffffffffff ffff83005da27ab8
(XEN)    ffff83005da27b08 ffff82d0802a3511 ffff82d08046b028 ffff83005da27b08
(XEN)    ffff82d0802a3511 ffff83005da27fff 0000138800000292 000082d0808176a0
(XEN)    0000000000000000 ffff82d08023b889 0000000000000292 ffff82d08046b028
(XEN)    ffff82d080451ac8 ffff82d080454af2 00000000000005a7 ffff83005da27b78
(XEN)    ffff82d080251d6f ffff82d080250fcd 0000000000000028 ffff83005da27b88
(XEN)    ffff83005da27b38 000000000000e010 ffff82d080454c73 ffff82d080451ac8
(XEN)    ffff82d080454af2 00000000000005a7 0000000000000030 ffff83005da27bf8
(XEN)    ffff82d080454c73 ffff83005da27be8 ffff82d0802aaebc ffff82d08033f3dc
(XEN)    ffff82d080451ac8 ffff82d08037d969 ffff82d08037d95d ffff82d08037d969
(XEN)    0b0f82d08037d95d ffff82d08037d969 ffff83005fe5b000 0000000000000000
(XEN)    0000000000000000 ffff83005da27fff 0000000000000000 00007cffa25d83e7
(XEN)    ffff82d08037da2d deadbeefdeadf00d ffff83018caf2530 ffff83005da27d38
(XEN)    ffff83040a492830 ffff83005da27cc8 ffff83040bab2880 0000000000000000
(XEN)    0000000000000000 deadbeefdeadf00d deadbeefdeadf00d 0000000000000000
(XEN)    0000000000000000 ffff830451835000 0000000000000000 ffff83040a492000
(XEN)    0000000600000000 ffff82d08033f3da 000000000000e008 0000000000010282
(XEN) Xen call trace:
(XEN)    [<000000007bdb630c>] 000000007bdb630c
(XEN)
(XEN) Pagetable walk from 00000000ee138470:
(XEN)  L4[0x000] = 000000046d2ee063 ffffffffffffffff
(XEN)  L3[0x003] = 000000005da11063 ffffffffffffffff
(XEN)  L2[0x170] = 0000000000000000 ffffffffffffffff
(XEN)
(XEN) ****************************************
(XEN) Panic on CPU 0:
(XEN) FATAL PAGE FAULT
(XEN) [error_code=0002]
(XEN) Faulting linear address: 00000000ee138470
(XEN) ****************************************
(XEN)
(XEN) Reboot in five seconds...

Tamas

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