On 10/09/2018 03:12 PM, Michael Bringmann wrote:
> The PPC mobility code may receive RTAS requests to perform PRRN
> topology changes at any time, including during LPAR migration
> operations. In some configurations where the affinity of CPUs
> or memory is being changed on that platform, the PRRN requests
> may apply or refer to outdated information prior to the complete
> update of the device-tree. This patch changes the duration for
> which topology updates are suppressed during LPAR migrations from
> just the rtas_ibm_suspend_me / 'ibm,suspend-me' call(s) to cover
> the entire 'migration_store' operation to allow all changes to
> the device-tree to be applied prior to accepting and applying any
> PRRN requests.
>
> For tracking purposes, pr_info notices are added to the functions
> start_topology_update() and stop_topology_update() of 'numa.c'.
>
> Signed-off-by: Michael Bringmann <m...@linux.vnet.ibm.com>
Reviewed-by: Nathan Fontenot <nf...@linux.vnet.ibm.com>
> ---
> Changes in v02:
> -- Rebase to latest powerpc next tree.
> ---
> arch/powerpc/kernel/rtas.c | 2 --
> arch/powerpc/mm/numa.c | 6 ++++++
> arch/powerpc/platforms/pseries/mobility.c | 5 +++++
> 3 files changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
> index 2c7ed31..e02ac37 100644
> --- a/arch/powerpc/kernel/rtas.c
> +++ b/arch/powerpc/kernel/rtas.c
> @@ -982,7 +982,6 @@ int rtas_ibm_suspend_me(u64 handle)
> }
>
> cpu_hotplug_disable();
> - stop_topology_update();
>
> /* Call function on all CPUs. One of us will make the
> * rtas call
> @@ -995,7 +994,6 @@ int rtas_ibm_suspend_me(u64 handle)
> if (atomic_read(&data.error) != 0)
> printk(KERN_ERR "Error doing global join\n");
>
> - start_topology_update();
> cpu_hotplug_enable();
>
> /* Take down CPUs not online prior to suspend */
> diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> index b5a71ba..0ade0a1 100644
> --- a/arch/powerpc/mm/numa.c
> +++ b/arch/powerpc/mm/numa.c
> @@ -1518,6 +1518,10 @@ int start_topology_update(void)
> }
> }
>
> + pr_info("Starting topology update%s%s\n",
> + (prrn_enabled ? " prrn_enabled" : ""),
> + (vphn_enabled ? " vphn_enabled" : ""));
> +
> return rc;
> }
>
> @@ -1539,6 +1543,8 @@ int stop_topology_update(void)
> rc = del_timer_sync(&topology_timer);
> }
>
> + pr_info("Stopping topology update\n");
> +
> return rc;
> }
>
> diff --git a/arch/powerpc/platforms/pseries/mobility.c
> b/arch/powerpc/platforms/pseries/mobility.c
> index 2f0f512..7da222d 100644
> --- a/arch/powerpc/platforms/pseries/mobility.c
> +++ b/arch/powerpc/platforms/pseries/mobility.c
> @@ -367,6 +367,8 @@ static ssize_t migration_store(struct class *class,
> if (rc)
> return rc;
>
> + stop_topology_update();
> +
> do {
> rc = rtas_ibm_suspend_me(streamid);
> if (rc == -EAGAIN)
> @@ -377,6 +379,9 @@ static ssize_t migration_store(struct class *class,
> return rc;
>
> post_mobility_fixup();
> +
> + start_topology_update();
> +
> return count;
> }
>
>
