> On Thu, 23 Mar 2017, Peter Zijlstra wrote: > > On Thu, Mar 23, 2017 at 11:25:49AM -0700, [email protected] wrote: > > > + for_each_possible_cpu(cpu) { > > > + rdmsrl_on_cpu(cpu, MSR_IA32_DEBUGCTLMSR, > &debugctlmsr); > > > + if (val) > > > + wrmsrl_on_cpu(cpu, MSR_IA32_DEBUGCTLMSR, > debugctlmsr | DEBUGCTLMSR_FREEZE_WHILE_SMM); > > > + else > > > + wrmsrl_on_cpu(cpu, MSR_IA32_DEBUGCTLMSR, > debugctlmsr & ~DEBUGCTLMSR_FREEZE_WHILE_SMM); > > > + } > > > > No; that's just disgusting. Also {rd,wr}msr_on_cpu() should die, > > exactly because people end up writing crap like this. > > Aside of that this is completely broken against other users of > DEBUGCTLMSR because it's not atomic vs. the other modifications. >
OK. I will change it. I guess I need a way/function which can atomically rd,wr msr on all cpus. Are there existing alternative ways/functions to do that? Thanks, Kan
