linux/arch
Andrew Cooper 581b7f158f x86/cpu: Fix SMAP check in PVOPS environments
There appears to be no formal statement of what pv_irq_ops.save_fl() is
supposed to return precisely.  Native returns the full flags, while lguest and
Xen only return the Interrupt Flag, and both have comments by the
implementations stating that only the Interrupt Flag is looked at.  This may
have been true when initially implemented, but no longer is.

To make matters worse, the Xen PVOP leaves the upper bits undefined, making
the BUG_ON() undefined behaviour.  Experimentally, this now trips for 32bit PV
guests on Broadwell hardware.  The BUG_ON() is consistent for an individual
build, but not consistent for all builds.  It has also been a sitting timebomb
since SMAP support was introduced.

Use native_save_fl() instead, which will obtain an accurate view of the AC
flag.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Tested-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: <lguest@lists.ozlabs.org>
Cc: Xen-devel <xen-devel@lists.xen.org>
CC: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1433323874-6927-1-git-send-email-andrew.cooper3@citrix.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-11-19 11:07:49 +01:00
..
alpha Linux 4.3-rc6 2015-10-20 10:16:46 +02:00
arc Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-11-03 16:10:43 -08:00
arm Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-11-03 16:10:43 -08:00
arm64 Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-11-03 16:10:43 -08:00
avr32 Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-11-03 16:10:43 -08:00
blackfin Merge branch 'strscpy' of git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile 2015-10-04 16:31:13 +01:00
c6x irqdomain: Use irq_domain_get_of_node() instead of direct field access 2015-10-13 19:01:23 +02:00
cris cris: Drop reference to get_cmos_time() 2015-11-02 20:03:05 +01:00
frv Linux 4.3-rc4 2015-10-06 17:10:28 +02:00
h8300 Linux 4.3-rc6 2015-10-20 10:16:46 +02:00
hexagon Linux 4.3-rc4 2015-10-06 17:10:28 +02:00
ia64 Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-11-03 16:10:43 -08:00
m32r Linux 4.3-rc4 2015-10-06 17:10:28 +02:00
m68k Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-11-03 16:10:43 -08:00
metag Linux 4.3-rc4 2015-10-06 17:10:28 +02:00
microblaze Merge branch 'strscpy' of git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile 2015-10-04 16:31:13 +01:00
mips Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-11-03 16:10:43 -08:00
mn10300 Linux 4.3-rc4 2015-10-06 17:10:28 +02:00
nios2 Merge branch 'strscpy' of git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile 2015-10-04 16:31:13 +01:00
openrisc
parisc atomic, arch: Audit atomic_{read,set}() 2015-09-23 09:54:28 +02:00
powerpc Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-11-03 17:38:09 -08:00
s390 Merge branch 'perf/urgent' into perf/core, before pulling new changes 2015-10-08 10:52:18 +02:00
score Merge branch 'strscpy' of git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile 2015-10-04 16:31:13 +01:00
sh Linux 4.3-rc6 2015-10-20 10:16:46 +02:00
sparc Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-11-03 17:38:09 -08:00
tile Linux 4.3-rc6 2015-10-20 10:16:46 +02:00
um um: Fix kernel mode fault condition 2015-10-19 22:53:37 +02:00
unicore32 Merge branch 'strscpy' of git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile 2015-10-04 16:31:13 +01:00
x86 x86/cpu: Fix SMAP check in PVOPS environments 2015-11-19 11:07:49 +01:00
xtensa Linux 4.3-rc4 2015-10-06 17:10:28 +02:00
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