On 02/28/2017 07:30 AM, Nicholas Piggin wrote:
> A synchronous machine check is an exception raised by the attempt to
> execute the current instruction. If the error can't be corrected, it
> can make sense to SIGBUS the currently running process.
>
> In other cases, the error condition is not related to the current
> instruction, so killing the current process is not the right thing to
> do.
>
> Today, all machine checks are MCE_SEV_ERROR_SYNC, so this has no
> practical change. It will be used to handle POWER9 asynchronous
> machine checks.
>
> Signed-off-by: Nicholas Piggin <npig...@gmail.com>
> ---
> arch/powerpc/platforms/powernv/opal.c | 21 ++++++---------------
> 1 file changed, 6 insertions(+), 15 deletions(-)
>
> diff --git a/arch/powerpc/platforms/powernv/opal.c
> b/arch/powerpc/platforms/powernv/opal.c
> index 86d9fde93c17..e0f856bfbfe8 100644
> --- a/arch/powerpc/platforms/powernv/opal.c
> +++ b/arch/powerpc/platforms/powernv/opal.c
> @@ -395,7 +395,6 @@ static int opal_recover_mce(struct pt_regs *regs,
> struct machine_check_event *evt)
> {
> int recovered = 0;
> - uint64_t ea = get_mce_fault_addr(evt);
>
> if (!(regs->msr & MSR_RI)) {
> /* If MSR_RI isn't set, we cannot recover */
> @@ -404,26 +403,18 @@ static int opal_recover_mce(struct pt_regs *regs,
> } else if (evt->disposition == MCE_DISPOSITION_RECOVERED) {
> /* Platform corrected itself */
> recovered = 1;
> - } else if (ea && !is_kernel_addr(ea)) {
> + } else if (evt->severity == MCE_SEV_FATAL) {
> + /* Fatal machine check */
> + pr_err("Machine check interrupt is fatal\n");
> + recovered = 0;
Setting recovered = 0 would trigger kernel panic. Should we panic the
kernel for asynchronous errors ?
> + } else if ((evt->severity == MCE_SEV_ERROR_SYNC) &&
> + (user_mode(regs) && !is_global_init(current))) {
> /*
> - * Faulting address is not in kernel text. We should be fine.
> - * We need to find which process uses this address.
> * For now, kill the task if we have received exception when
> * in userspace.
> *
> * TODO: Queue up this address for hwpoisioning later.
> */
> - if (user_mode(regs) && !is_global_init(current)) {
> - _exception(SIGBUS, regs, BUS_MCEERR_AR, regs->nip);
> - recovered = 1;
> - } else
> - recovered = 0;
> - } else if (user_mode(regs) && !is_global_init(current) &&
> - evt->severity == MCE_SEV_ERROR_SYNC) {
> - /*
> - * If we have received a synchronous error when in userspace
> - * kill the task.
> - */
> _exception(SIGBUS, regs, BUS_MCEERR_AR, regs->nip);
> recovered = 1;
> }
>
