This was sent in error. Sorry,
P. On 6/16/20 7:27 AM, Prarit Bhargava wrote: > There are two problems with kernel messages in fatal mode that were found > during testing of guests and userspace programs. > > The first is that no kernel message is output when the split lock detector > is triggered with a userspace program. As a result the userspace process > dies from receiving SIGBUS with no indication to the user of what caused > the process to die. > > The second problem is that only the first triggering guest causes a kernel > message to be output because the message is output with pr_warn_once(). > This also results in a loss of information to the user. > > While fixing these I noticed that the same message was being output > three times so I'm cleaning that up too. > > Fix fatal mode output, and use consistent messages for fatal and > warn modes for both userspace and guests. > > Co-developed-by: Sean Christopherson <sean.j.christopher...@intel.com> > Signed-off-by: Sean Christopherson <sean.j.christopher...@intel.com> > Cc: Thomas Gleixner <t...@linutronix.de> > Cc: Ingo Molnar <mi...@redhat.com> > Cc: Borislav Petkov <b...@alien8.de> > Cc: x...@kernel.org > Cc: "H. Peter Anvin" <h...@zytor.com> > Cc: Tony Luck <tony.l...@intel.com> > Cc: "Peter Zijlstra (Intel)" <pet...@infradead.org> > Cc: Sean Christopherson <sean.j.christopher...@intel.com> > Cc: Rahul Tanwar <rahul.tan...@linux.intel.com> > Cc: Xiaoyao Li <xiaoyao...@intel.com> > Cc: Ricardo Neri <ricardo.neri-calde...@linux.intel.com> > Cc: Dave Hansen <dave.han...@linux.intel.com> > --- > v2: Do not output a message if CPL 3 Alignment Check is turned on (xiaoyao.li) > v3: refactor code (sean.j.christopherson) > v4: Fix Sign off (sean.j.christopherson) > > arch/x86/kernel/cpu/intel.c | 22 ++++++++++------------ > 1 file changed, 10 insertions(+), 12 deletions(-) > > diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c > index 63926c94eb5f..3a373f0be674 100644 > --- a/arch/x86/kernel/cpu/intel.c > +++ b/arch/x86/kernel/cpu/intel.c > @@ -1074,11 +1074,14 @@ static void split_lock_init(void) > split_lock_verify_msr(sld_state != sld_off); > } > > -static void split_lock_warn(unsigned long ip) > +static bool handle_split_lock(unsigned long ip) > { > - pr_warn_ratelimited("#AC: %s/%d took a split_lock trap at address: > 0x%lx\n", > + pr_warn("#AC: %s/%d took a split_lock trap at address: 0x%lx\n", > current->comm, current->pid, ip); > > + if (sld_state != sld_warn) > + return false; > + > /* > * Disable the split lock detection for this task so it can make > * progress and set TIF_SLD so the detection is re-enabled via > @@ -1086,18 +1089,13 @@ static void split_lock_warn(unsigned long ip) > */ > sld_update_msr(false); > set_tsk_thread_flag(current, TIF_SLD); > + return true; > } > > bool handle_guest_split_lock(unsigned long ip) > { > - if (sld_state == sld_warn) { > - split_lock_warn(ip); > + if (handle_split_lock(ip)) > return true; > - } > - > - pr_warn_once("#AC: %s/%d %s split_lock trap at address: 0x%lx\n", > - current->comm, current->pid, > - sld_state == sld_fatal ? "fatal" : "bogus", ip); > > current->thread.error_code = 0; > current->thread.trap_nr = X86_TRAP_AC; > @@ -1108,10 +1106,10 @@ EXPORT_SYMBOL_GPL(handle_guest_split_lock); > > bool handle_user_split_lock(struct pt_regs *regs, long error_code) > { > - if ((regs->flags & X86_EFLAGS_AC) || sld_state == sld_fatal) > + if (regs->flags & X86_EFLAGS_AC) > return false; > - split_lock_warn(regs->ip); > - return true; > + > + return handle_split_lock(regs->ip); > } > > /* >