On Fri, 2016-12-23 at 18:11 -0800, Andy Lutomirski wrote: > On Fri, Dec 23, 2016 at 5:37 PM, Ricardo Neri > <ricardo.neri-calde...@linux.intel.com> wrote: > > If the User-Mode Instruction Prevention CPU feature is available and > > enabled, a general protection fault will be issued if the instructions > > sgdt, sldt, sidt, str or smsw are executed from user-mode context > > (CPL > 0). If the fault was caused by any of the instructions protected > > by UMIP, fixup_umip_exceptino will emulate dummy results for these > > instructions. > > > > Cc: Andy Lutomirski <l...@kernel.org> > > Cc: Andrew Morton <a...@linux-foundation.org> > > Cc: H. Peter Anvin <h...@zytor.com> > > Cc: Borislav Petkov <b...@suse.de> > > Cc: Brian Gerst <brge...@gmail.com> > > Cc: Chen Yucong <sla...@gmail.com> > > Cc: Chris Metcalf <cmetc...@mellanox.com> > > Cc: Dave Hansen <dave.han...@linux.intel.com> > > Cc: Fenghua Yu <fenghua...@intel.com> > > Cc: Huang Rui <ray.hu...@amd.com> > > Cc: Jiri Slaby <jsl...@suse.cz> > > Cc: Jonathan Corbet <cor...@lwn.net> > > Cc: Michael S. Tsirkin <m...@redhat.com> > > Cc: Paul Gortmaker <paul.gortma...@windriver.com> > > Cc: Peter Zijlstra <pet...@infradead.org> > > Cc: Ravi V. Shankar <ravi.v.shan...@intel.com> > > Cc: Shuah Khan <sh...@kernel.org> > > Cc: Vlastimil Babka <vba...@suse.cz> > > Cc: Tony Luck <tony.l...@intel.com> > > Cc: Paolo Bonzini <pbonz...@redhat.com> > > Cc: Liang Z. Li <liang.z...@intel.com> > > Cc: Alexandre Julliard <julli...@winehq.org> > > Cc: Stas Sergeev <s...@list.ru> > > Cc: x...@kernel.org > > Cc: linux-ms...@vger.kernel.org > > Signed-off-by: Ricardo Neri <ricardo.neri-calde...@linux.intel.com> > > --- > > arch/x86/kernel/traps.c | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c > > index bf0c6d0..5044fb3 100644 > > --- a/arch/x86/kernel/traps.c > > +++ b/arch/x86/kernel/traps.c > > @@ -64,6 +64,7 @@ > > #include <asm/trace/mpx.h> > > #include <asm/mpx.h> > > #include <asm/vm86.h> > > +#include <asm/umip.h> > > > > #ifdef CONFIG_X86_64 > > #include <asm/x86_init.h> > > @@ -491,6 +492,9 @@ do_general_protection(struct pt_regs *regs, long > > error_code) > > RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU"); > > cond_local_irq_enable(regs); > > > > + if (user_mode(regs) && !fixup_umip_exception(regs)) > > + return; > > + > > I would do fixup_umip_exception(regs) == 0 to make it more obvious > what's going on.
Sure. I will make this change. > > Also, since you're allowing this in v8086 mode, I think this should > have an explicit test in > tools/testing/selftests/x86/entry_from_vm86.c. I *think* it will work > fine, but the pt_regs handling in vm86 mode is quite scary and has > been rewritten recently. I will include a test for this. Thanks and BR, Ricardo
