On Wed, 2009-11-25 at 21:24 +, Jeremy Fitzhardinge wrote:
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
Ian Campbell ian.campb...@citrix.com 23.11.09 17:44
On Mon, 2009-11-23 at 16:31 +, Jan Beulich wrote:
It does not happen on XenSource 2.6.18 kernel
I assume that this kernel (perhaps coincidentally) manages to use
FLAT_USER_CS32 for compat mode processes.
, or the Debian 2.6.26
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
Jeremy Fitzhardinge jer...@goop.org 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
On Tue, 2009-11-24 at 00:39 +, Jeremy Fitzhardinge wrote:
On 11/23/09 07:25, Ian Campbell wrote:
On Sun, 2009-11-22 at 09:54 +, Bastian Blank wrote:
On Tue, Nov 17, 2009 at 10:04:36PM +0300, William Pitcock wrote:
[1.254927] init[1] general protection ip:f779042f
On Sun, 2009-11-22 at 09:54 +, Bastian Blank wrote:
On Tue, Nov 17, 2009 at 10:04:36PM +0300, William Pitcock wrote:
[1.254927] init[1] general protection ip:f779042f sp:ff9b0340 error:0
Hmm, this looks like the old Debian bug 544145[1]. For some reason the
hypervisor jumps back
On Mon, Nov 23, 2009 at 03:25:35PM +, Ian Campbell wrote:
We are attempting to return to the Linux defined __USER_CS32 (0x23)
which does not match the test for the Xen defined FLAT_USER_CS32
(0xe023) and therefore we hit the sysretq instead of the sysretl which
causes us to return with CS
On Mon, 2009-11-23 at 16:31 +, Bastian Blank wrote:
On Mon, Nov 23, 2009 at 03:25:35PM +, Ian Campbell wrote:
We are attempting to return to the Linux defined __USER_CS32 (0x23)
which does not match the test for the Xen defined FLAT_USER_CS32
(0xe023) and therefore we hit the
On Mon, 2009-11-23 at 16:31 +, Jan Beulich wrote:
Ian Campbell ian.campb...@citrix.com 23.11.09 16:25
Perhaps simply not returning guest userspace with sysret (as above)
makes most sense, a syscall already takes a trap through the hypervisor
on both entry and exit so I'm not sure the
Ian Campbell ian.campb...@citrix.com 23.11.09 16:25
Perhaps simply not returning guest userspace with sysret (as above)
makes most sense, a syscall already takes a trap through the hypervisor
on both entry and exit so I'm not sure the difference between sysret and
iret is going to be noticeable.
On Mon, 2009-11-23 at 17:13 +, Keir Fraser wrote:
On 23/11/2009 16:44, Ian Campbell ian.campb...@citrix.com wrote:
But this is not just the return-to-user-space path you're changing, but
also the hypercall one. You certainly don't want an iret in that case.
Don't the hypercalls
On Mon, Nov 23, 2009 at 04:42:59PM +, Ian Campbell wrote:
On Mon, 2009-11-23 at 16:31 +, Bastian Blank wrote:
The code actually have to know if it was called from 64 or compatibility
mode, not assume it.
Sounds correct. This is tricky for a hypervisor since we don't know the
mode of
On 23/11/2009 16:44, Ian Campbell ian.campb...@citrix.com wrote:
But this is not just the return-to-user-space path you're changing, but
also the hypercall one. You certainly don't want an iret in that case.
Don't the hypercalls already always go via iret?
-testw
On 11/23/09 07:25, Ian Campbell wrote:
On Sun, 2009-11-22 at 09:54 +, Bastian Blank wrote:
On Tue, Nov 17, 2009 at 10:04:36PM +0300, William Pitcock wrote:
[1.254927] init[1] general protection ip:f779042f sp:ff9b0340 error:0
Hmm, this looks like the old Debian bug
On 11/23/09 09:23, Bastian Blank wrote:
I don't believe that is the case (the processor would have to carry some
state for the entire duration of a syscall for it to make any
difference). I think the spec simply assumes that an OS author would
want to use sysret if they used syscall.
15 matches
Mail list logo
