x86/iopl/64: Properly context-switch IOPL on Xen PV
authorAndy Lutomirski <luto@kernel.org>
Wed, 16 Mar 2016 21:14:21 +0000 (14:14 -0700)
committerIngo Molnar <mingo@kernel.org>
Thu, 17 Mar 2016 08:49:26 +0000 (09:49 +0100)
commitb7a584598aea7ca73140cb87b40319944dd3393f
tree79f30be94b46b3bf08eb2ab82921973fef2c0064
parentb08983015cdddca7e41c95f5054e2a8fb222a264
x86/iopl/64: Properly context-switch IOPL on Xen PV

On Xen PV, regs->flags doesn't reliably reflect IOPL and the
exit-to-userspace code doesn't change IOPL.  We need to context
switch it manually.

I'm doing this without going through paravirt because this is
specific to Xen PV.  After the dust settles, we can merge this with
the 32-bit code, tidy up the iopl syscall implementation, and remove
the set_iopl pvop entirely.

Fixes XSA-171.

Reviewewd-by: Jan Beulich <JBeulich@suse.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jan Beulich <JBeulich@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/693c3bd7aeb4d3c27c92c622b7d0f554a458173c.1458162709.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
arch/x86/include/asm/xen/hypervisor.h
arch/x86/kernel/process_64.c
arch/x86/xen/enlighten.c