From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from list by lists.gnu.org with archive (Exim 4.71) id 1aMbGf-00056E-Mn for mharc-grub-devel@gnu.org; Fri, 22 Jan 2016 07:56:45 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34351) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aMbGZ-00054w-Gg for grub-devel@gnu.org; Fri, 22 Jan 2016 07:56:43 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aMbGX-0002ec-Pr for grub-devel@gnu.org; Fri, 22 Jan 2016 07:56:39 -0500 Received: from mail-wm0-x229.google.com ([2a00:1450:400c:c09::229]:36409) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aMbGX-0002eS-Ew for grub-devel@gnu.org; Fri, 22 Jan 2016 07:56:37 -0500 Received: by mail-wm0-x229.google.com with SMTP id l65so259946911wmf.1 for ; Fri, 22 Jan 2016 04:56:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=subject:to:references:cc:from:message-id:date:user-agent :mime-version:in-reply-to:content-type; bh=0Vf1LJebnosYy/oquXwV2gzYU+7+YI9mV19HrCC0MAk=; b=jWQz2aDoK7C/RS++hmVVj01eULaVcNUPv+hTHQoDQhrIn88bV681kaiSRy7pyWY702 EUDCfdGlntrgS1aow+2ZGp+mXXqkq/Gi12ThfGglcLxXDUgnjKrILXFmEmPQf/xCo9o+ 6YydezO0LOh1360GI3GV5WSnkzCQWHnQ+y2DMBUGuLx/PtyXTwRInJAkVKqajBLMSf1m xZmFQ11adcRrm2bBp/7GjnzSlKO00wuEa18dptbZgmTGHvEXNJvAzFW9JPQz+RtFB5SM d7sHfYrI2fxEkYKImoo0jFNXRlWubo+q2CQ14/2XTWvunywWZrS6MD0WcSHJHx+d2oju lcXw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:subject:to:references:cc:from:message-id:date :user-agent:mime-version:in-reply-to:content-type; bh=0Vf1LJebnosYy/oquXwV2gzYU+7+YI9mV19HrCC0MAk=; b=hvJBNMPFw5tvft4JZAUZSU8bq3M+jlZxu3eVQA0P8Vbk8vy/IoIJStxidMLruEzLgK GJJ8qC/d3y61LSB+zM/gBJhrYJRenOFAiZy4DDjTmzcRjEw20lGx4FduSzdrn8gY7Bi7 iYlwls0hfvZSTb3M9unp01TzYGoWLcbZVpdfknAMutuL73QjVc/NpoKGEyjxEf7oEAXn X7ipCeK3aDJ/gXedD3mSBuhbET6Fa0V4f0zR0poEBrAaoksAIgePiWuoMCdv7Jn7EFDg +R4BW3fXeUw7Z334mk33O8oqnKchH4PggqOGLAx1P62jijw0E86ab3fgzTfXU0F8tm4/ GvIw== X-Gm-Message-State: AG10YOQoVy4zzo4AOJ+aJEmgIX+mNGK32Qc+hFyWbwJRY1LBXyCDopkoVo8czP4qAqKmKg== X-Received: by 10.194.83.136 with SMTP id q8mr3018407wjy.51.1453467396714; Fri, 22 Jan 2016 04:56:36 -0800 (PST) Received: from ?IPv6:2a02:120b:2c41:63f0:a2a8:cdff:fe64:b3b5? ([2a02:120b:2c41:63f0:a2a8:cdff:fe64:b3b5]) by smtp.gmail.com with ESMTPSA id w1sm2841864wmd.2.2016.01.22.04.56.34 (version=TLSv1/SSLv3 cipher=OTHER); Fri, 22 Jan 2016 04:56:34 -0800 (PST) Subject: Re: [Xen-devel] [BUG] XEN domU crash when PV grub chainloads 32-bit domU grub To: Ian Campbell , grub-devel@gnu.org References: <5600628A.20202@zappa.cx> <1442912018.10338.118.camel@citrix.com> From: =?UTF-8?Q?Vladimir_'=cf=86-coder/phcoder'_Serbinenko?= Message-ID: <56A226F8.3020301@gmail.com> Date: Fri, 22 Jan 2016 13:56:24 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Icedove/38.5.0 MIME-Version: 1.0 In-Reply-To: <1442912018.10338.118.camel@citrix.com> Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="bu17pAf0UtvBt8D6sP0Wd55TbEoG146I1" X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 2a00:1450:400c:c09::229 Cc: Andreas Sundstrom , xen-devel@lists.xen.org X-BeenThere: grub-devel@gnu.org X-Mailman-Version: 2.1.14 Precedence: list Reply-To: The development of GNU GRUB List-Id: The development of GNU GRUB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 22 Jan 2016 12:56:44 -0000 This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --bu17pAf0UtvBt8D6sP0Wd55TbEoG146I1 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 22.09.2015 10:53, Ian Campbell wrote: > Hi Vladimir & grub-devel, >=20 > Do you have any thoughts on this issue with i386 pv-grub2? >=20 Is it still an issue? If so I'll try to replicate it. From stack dump I see that it has jumped to NULL. GRUB has no threads so it's not a race condition with itself but may be one with some Xen part. An altrnative possibility is that grub forgets to flush cache at some point in boot process. > Thanks, Ian. >=20 > On Mon, 2015-09-21 at 22:03 +0200, Andreas Sundstrom wrote: >> This is using Debian Jessie and grub 2.02~beta2-22 (with Debian patche= s >> applied) and Xen 4.4.1 >> >> I originally posted a bug report with Debian but got the suggestion to= >> file bugs with upstream as well. >> Debian bug report: >> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=3D799480 >> >> Note that my original thought was that this bug probably is within GRU= B. >> But Ian asked me to file a bug with Xen as well, you have to live with= >> the >> fact that it is centered around GRUB though. >> >> Here's the information from my original bug report: >> >> Using 64-bit dom0 and 32-bit domU PV (para-virtualized) grub sometimes= >> fail when chainloading the domU's grub. 64-bit domU seem to work 100% >> of the time. >> >> My understanding of the process: >> >> * dom0 launches domU with grub that is loaded from dom0's disk. >> * Grub reads config file from memdisk, and then looks for grub binary= in >> domU filesystem. >> * If grub is found in domU it then chainloads (multiboot) that grub >> binary >> and the domU grub reads grub.cfg and continue booting. >> * If grub is not found in domU it reads grub.cfg and continues with >> boot. >> >> It fails at step 3 in my list of the boot process, but sometimes it >> does work so it may be something like a race condition that causes the= >> problem? >> >> A workaround is to not install or rename /boot/xen in domU so that the= >> first grub that is loaded from dom0's disk will not find the grub >> binary in the domU filesystem and hence continues to read grub.cfg and= >> boot. The drawback of this is of course that the two versions can't >> differ too much as there are different setups creating grub.cfg and >> then reading/parsing it at boot time. >> >> I am not sure at this point whether this is a problem in XEN or a >> problem in grub but I compiled the legacy pvgrub that uses some minios= >> from XEN (don't really know much more about it) and when that legacy >> pvgrub chainloads the domU grub it seems to work 100% of the time. Now= >> the legace pvgrub is not a real alternative as it's not packaged for >> Debian though. >> >> When it fails "xl create vm -c" outputs this: >> Parsing config from /etc/xen/vm >> libxl: error: libxl_dom.c:35:libxl__domain_type: unable to get domain >> type for domid=3D16 >> Unable to attach console >> libxl: error: libxl_exec.c:118:libxl_report_child_exitstatus: console >> child [0] exited with error status 1 >> >> And "xl dmesg" shows errors like this: >> (XEN) traps.c:2514:d15 Domain attempted WRMSR 00000000c0010201 from >> 0x0000000000000000 to 0x000000000000ffff. >> (XEN) d16:v0: unhandled page fault (ec=3D0010) >> (XEN) Pagetable walk from 0000000000000000: >> (XEN) L4[0x000] =3D 0000000200256027 000000000000049c >> (XEN) L3[0x000] =3D 0000000200255027 000000000000049d >> (XEN) L2[0x000] =3D 0000000200251023 00000000000004a1 >> (XEN) L1[0x000] =3D 0000000000000000 ffffffffffffffff >> (XEN) domain_crash_sync called from entry.S: fault at ffff82d08021feb0= >> compat_create_bounce_frame+0xc6/0xde >> (XEN) Domain 16 (vcpu#0) crashed on cpu#0: >> (XEN) ----[ Xen-4.4.1 x86_64 debug=3Dn Not tainted ]---- >> (XEN) CPU: 0 >> (XEN) RIP: e019:[<0000000000000000>] >> (XEN) RFLAGS: 0000000000000246 EM: 1 CONTEXT: pv guest >> (XEN) rax: 0000000000000000 rbx: 0000000000000000 rcx: 000000000000000= 0 >> (XEN) rdx: 0000000000000000 rsi: 0000000000499000 rdi: 000000000080000= 0 >> (XEN) rbp: 000000000000000a rsp: 00000000005a5ff0 r8: 0000000000000000= >> (XEN) r9: 0000000000000000 r10: ffff83023e9b9000 r11: ffff83023e9b9000= >> (XEN) r12: 0000033f3d335bfb r13: ffff82d080300800 r14: ffff82d0802ea94= 0 >> (XEN) r15: ffff83005e819000 cr0: 000000008005003b cr4: 00000000000506f= 0 >> (XEN) cr3: 0000000200b7a000 cr2: 0000000000000000 >> (XEN) ds: e021 es: e021 fs: e021 gs: e021 ss: e021 cs: e019 >> (XEN) Guest stack trace from esp=3D005a5ff0: >> (XEN) 00000010 00000000 0001e019 00010046 0016b38b 0016b38a 0016b389 >> 0016b388 >> (XEN) 0016b387 0016b386 0016b385 0016b384 0016b383 0016b382 0016b381 >> 0016b380 >> (XEN) 0016b37f 0016b37e 0016b37d 0016b37c 0016b37b 0016b37a 0016b379 >> 0016b378 >> (XEN) 0016b377 0016b376 0016b375 0016b374 0016b373 0016b372 0016b371 >> 0016b370 >> (XEN) 0016b36f 0016b36e 0016b36d 0016b36c 0016b36b 0016b36a 0016b369 >> 0016b368 >> (XEN) 0016b367 0016b366 0016b365 0016b364 0016b363 0016b362 0016b361 >> 0016b360 >> (XEN) 0016b35f 0016b35e 0016b35d 0016b35c 0016b35b 0016b35a 0016b359 >> 0016b358 >> (XEN) 0016b357 0016b356 0016b355 0016b354 0016b353 0016b352 0016b351 >> 0016b350 >> (XEN) 0016b34f 0016b34e 0016b34d 0016b34c 0016b34b 0016b34a 0016b349 >> 0016b348 >> (XEN) 0016b347 0016b346 0016b345 0016b344 0016b343 0016b342 0016b341 >> 0016b340 >> (XEN) 0016b33f 0016b33e 0016b33d 0016b33c 0016b33b 0016b33a 0016b339 >> 0016b338 >> (XEN) 0016b337 0016b336 0016b335 0016b334 0016b333 0016b332 0016b331 >> 0016b330 >> (XEN) 0016b32f 0016b32e 0016b32d 0016b32c 0016b32b 0016b32a 0016b329 >> 0016b328 >> (XEN) 0016b327 0016b326 0016b325 0016b324 0016b323 0016b322 0016b321 >> 0016b320 >> (XEN) 0016b31f 0016b31e 0016b31d 0016b31c 0016b31b 0016b31a 0016b319 >> 0016b318 >> (XEN) 0016b317 0016b316 0016b315 0016b314 0016b313 0016b312 0016b311 >> 0016b310 >> (XEN) 0016b30f 0016b30e 0016b30d 0016b30c 0016b30b 0016b30a 0016b309 >> 0016b308 >> (XEN) 0016b307 0016b306 0016b305 0016b304 0016b303 0016b302 0016b301 >> 0016b300 >> (XEN) 0016b2ff 0016b2fe 0016b2fd 0016b2fc 0016b2fb 0016b2fa 0016b2f9 >> 0016b2f8 >> (XEN) 0016b2f7 0016b2f6 0016b2f5 0016b2f4 0016b2f3 0016b2f2 0016b2f1 >> 0016b2f0 >> >> An easy way to find out which grub you are in if the machine boots is >> to hit 'c' and type 'ls', only the grub from dom0 will know about >> (memdisk). So when trying to replicate the issue (and the domU >> actually starts) you can hit 'c', type 'ls' (check for memdisk) and >> then type 'halt' and relaunch the domU. Usually I can't launch more >> than 4-5 times in a row before it fails, often it fails on my first >> try. >> >> For information I have reproduced on two different AMD desktop >> processor machines, not sure if Intel would be any different. I'm >> pretty sure I did tests with grub from unstable with same result at >> some point, but can test again if that is likely to work. >> >> The package that is in installed on the domU side is "grub-xen". >> >> I am unable to understand how to debug grub further on my own, I have >> printed out text from grub so that I understood that it is the >> chainload that fails. I see no output from the domU grub (except when >> it works as it should of course). I can help with further testing if >> needed. >> >> /Andreas >> >> >> _______________________________________________ >> Xen-devel mailing list >> Xen-devel@lists.xen.org >> http://lists.xen.org/xen-devel >=20 --bu17pAf0UtvBt8D6sP0Wd55TbEoG146I1 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iF4EAREKAAYFAlaiJvgACgkQmBXlbbo5nOvObAD/YlFMRTMTkwvVC0goKDHuT67C QAVEQyas+lyb35/8HRkA/2qvYragxDJLOmVFgddpZMTf1cPWUHBHUSGXJ5lnHX9n =ZtIz -----END PGP SIGNATURE----- --bu17pAf0UtvBt8D6sP0Wd55TbEoG146I1--