On Thu, Mar 26, 2020 at 12:29:04AM +1000, Nicholas Piggin wrote:
> Some of the conditions are not as clearly documented as they could be.
> Also the non-FWNMI case does not need a large comment.
>
> Reviewed-by: Greg Kurz
> Signed-off-by: Nicholas Piggin
Applied to ppc-for-5.0.
> ---
> hw/ppc/spapr_events.c | 19 +++
> 1 file changed, 11 insertions(+), 8 deletions(-)
>
> diff --git a/hw/ppc/spapr_events.c b/hw/ppc/spapr_events.c
> index a4a540f43d..a908c5d0e9 100644
> --- a/hw/ppc/spapr_events.c
> +++ b/hw/ppc/spapr_events.c
> @@ -860,17 +860,13 @@ void spapr_mce_req_event(PowerPCCPU *cpu, bool
> recovered)
> Error *local_err = NULL;
>
> if (spapr->fwnmi_machine_check_addr == -1) {
> -/*
> - * This implies that we have hit a machine check either when the
> - * guest has not registered FWNMI (i.e., "ibm,nmi-register" not
> - * called) or between system reset and "ibm,nmi-register".
> - * Fall back to the old machine check behavior in such cases.
> - */
> +/* Non-FWNMI case, deliver it like an architected CPU interrupt. */
> cs->exception_index = POWERPC_EXCP_MCHECK;
> ppc_cpu_do_interrupt(cs);
> return;
> }
>
> +/* Wait for FWNMI interlock. */
> while (spapr->fwnmi_machine_check_interlock != -1) {
> /*
> * Check whether the same CPU got machine check error
> @@ -882,8 +878,13 @@ void spapr_mce_req_event(PowerPCCPU *cpu, bool recovered)
> return;
> }
> qemu_cond_wait_iothread(>fwnmi_machine_check_interlock_cond);
> -/* Meanwhile if the system is reset, then just return */
> if (spapr->fwnmi_machine_check_addr == -1) {
> +/*
> + * If the machine was reset while waiting for the interlock,
> + * abort the delivery. The machine check applies to a context
> + * that no longer exists, so it wouldn't make sense to deliver
> + * it now.
> + */
> return;
> }
> }
> @@ -894,7 +895,9 @@ void spapr_mce_req_event(PowerPCCPU *cpu, bool recovered)
> * We don't want to abort so we let the migration to continue.
> * In a rare case, the machine check handler will run on the target.
> * Though this is not preferable, it is better than aborting
> - * the migration or killing the VM.
> + * the migration or killing the VM. It is okay to call
> + * migrate_del_blocker on a blocker that was not added (which the
> + * nmi-interlock handler would do when it's called after this).
> */
> warn_report("Received a fwnmi while migration was in progress");
> }
--
David Gibson| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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