From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jan Beulich" Subject: Re: Crash with paravirt-ops 2.6.31.6 kernel Date: Thu, 26 Nov 2009 07:35:25 +0000 Message-ID: <4B0E3DCD0200007800022260@vpn.id2.novell.com> References: <28846609.721258484676784.JavaMail.root@ifrit.dereferenced.org> <20091122095403.GA1496@wavehammer.waldi.eu.org> <1258989935.7590.52.camel@zakaz.uk.xensource.com> <4B0AC6FA0200007800021812@vpn.id2.novell.com> <1258994658.7590.80.camel@zakaz.uk.xensource.com> <4B0D13850200007800021FC6@vpn.id2.novell.com> <4B0DA080.7030904@goop.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <4B0DA080.7030904@goop.org> Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Jeremy Fitzhardinge Cc: "xen-devel@lists.xensource.com" , Bastian Blank , Ian Campbell , "544145@bugs.debian.org" <544145@bugs.debian.org> List-Id: xen-devel@lists.xenproject.org >>> Jeremy Fitzhardinge 25.11.09 22:24 >>> >On 11/25/09 02:22, Jan Beulich wrote: >> Okay, I think I spotted the relevant difference: 2.6.18 and forward = ports >> set VGCF_in_syscall only when returning from 64-bit system calls = (through >> ret_from_sys_call) - 32-bit syscalls (regardless of the entry path = taken) >> return through int_ret_from_sys_call. 32-bit guest kernels shouldn't be >> affected by this, as compat mode returns from the hypervisor >> (compat_restore_all_guest) always use iret. >> =20 > >I think dropping the VCGF_in_syscall flag is the simplest possible fix >then. There doesn't seem to be a huge benefit to using sysret in this >case. Does this look OK? Yes, with one (more cosmetic than really useful) adjustment - the flag should also be dropped from the !CONFIG_IA32_EMULATION code path at the end of the file. In any case, Acked-by: Jan Beulich Jan