Re: Resend: Linux 4.11-rc7: kernel BUG at drivers/xen/events/events_base.c:1221

From: Juergen Gross <jgross@suse.com>
To: Sander Eikelenboom <linux@eikelenboom.it>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: xen-devel@lists.xen.org
Subject: Re: Resend: Linux 4.11-rc7: kernel BUG at drivers/xen/events/events_base.c:1221
Date: Tue, 25 Apr 2017 13:17:52 +0200	[thread overview]
Message-ID: <b839c1d0-1a1a-cba9-51ac-a14e18102c95@suse.com> (raw)
In-Reply-To: <acc38319-7631-62c6-3608-95689d8eabdd@eikelenboom.it>

On 25/04/17 12:33, Sander Eikelenboom wrote:
> On 25/04/17 09:01, Juergen Gross wrote:
>> On 25/04/17 08:57, Sander Eikelenboom wrote:
>>> On 25/04/17 08:42, Juergen Gross wrote:
>>>> On 25/04/17 08:35, Sander Eikelenboom wrote:
>>>>> (XEN) [2017-04-24 21:20:53.203] d0v0 Unhandled invalid opcode fault/trap [#6, ec=ffffffff]
>>>>> (XEN) [2017-04-24 21:20:53.203] domain_crash_sync called from entry.S: fault at ffff82d080358f70 entry.o#create_bounce_frame+0x145/0x154
>>>>> (XEN) [2017-04-24 21:20:53.203] Domain 0 (vcpu#0) crashed on cpu#0:
>>>>> (XEN) [2017-04-24 21:20:53.203] ----[ Xen-4.9-unstable  x86_64  debug=y   Not tainted ]----
>>>>> (XEN) [2017-04-24 21:20:53.203] CPU:    0
>>>>> (XEN) [2017-04-24 21:20:53.203] RIP:    e033:[<ffffffff8255a485>]
>>>>
>>>> Can you please tell us symbol+offset for RIP?
>>>>
>>>> Juergen
>>>>
>>>
>>> Sure:
>>> # addr2line -e vmlinux-4.11.0-rc8-20170424-linus-doflr-xennext-boris+ ffffffff8255a485
>>> linux-linus/arch/x86/xen/enlighten_pv.c:288
>>>
>>> Which is:
>>> static bool __init xen_check_xsave(void)
>>> {
>>>         unsigned int err, eax, edx;
>>>
>>>         /*
>>>          * Xen 4.0 and older accidentally leaked the host XSAVE flag into guest
>>>          * view, despite not being able to support guests using the
>>>          * functionality. Probe for the actual availability of XSAVE by seeing
>>>          * whether xgetbv executes successfully or raises #UD.
>>>          */
>>> HERE -->    asm volatile("1: .byte 0x0f,0x01,0xd0\n\t" /* xgetbv */    
>>>                      "xor %[err], %[err]\n"
>>>                      "2:\n\t"
>>>                      ".pushsection .fixup,\"ax\"\n\t"
>>>                      "3: movl $1,%[err]\n\t"
>>>                      "jmp 2b\n\t"
>>>                      ".popsection\n\t"
>>>                      _ASM_EXTABLE(1b, 3b)
>>>                      : [err] "=r" (err), "=a" (eax), "=d" (edx)
>>>                      : "c" (0));
>>>
>>>         return err == 0;
>>
>> I hoped so. :-)
>>
>> I posted a patch to repair this some minutes ago. Would you mind to try
>> it? See:
>>
>> https://lists.xen.org/archives/html/xen-devel/2017-04/msg02925.html
>>
>>
>> Juergen
> 
> Hmm next up seems to be a hanging dom0 kernel somewhat later during boot, with not too many clues.
> (any output of xen debug-keys that could be of interest ?)

> mapping kernel into physical memory
> about to get started...
> [    0.000000] Linux version 4.11.0-rc8-20170425-linus-doflr-xennext-boris-juergen-2+ (root@serveerstertje) (gcc version 4.9.2 (Debian 4.9.2-10) ) #1 SMP Tue Apr 25 12:01:44 CEST 2017
> [    0.000000] Command line: root=/dev/mapper/serveerstertje_ssd-root ro verbose earlyprintk=xen mem=2048M console=hvc0 console=tty0 acpi_enforce_resources=lax max_loop=30 loop_max_part=10 r8169.use_dac=1 loglevel=10 nomodeset xen-pciback.hide=(00:14.2)(04:00.0)(08:00.0)(09:00.*)(0a:00.*)(0e:00.0)
> [    0.000000] x86/fpu: x87 FPU will use FXSAVE

As this is the expected message for a cpu without the XSAVE feature
(being the reason for the crash you had without my patch): can I add
your "Tested-by:" for my patch?

Juergen

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