Re: [PATCH v3 4/4] powerpc/pseries/vas: Disable window open during migration

[Nicholas Piggin <npiggin@gmail.com>]

Excerpts from Haren Myneni's message of February 20, 2022 6:08 am:
> 
> The current partition migration implementation does not freeze the
> user space and the user space can continue open VAS windows. So
> when migration_in_progress flag is enabled, VAS open window
> API returns -EBUSY.

Seems like it could be merged with the previous patch. Unless
you're trying to specifically call out the -EBUSY chane to the
API?

Thanks,
Nick

> 
> Signed-off-by: Haren Myneni <haren@linux.ibm.com>
> ---
>  arch/powerpc/platforms/pseries/vas.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/pseries/vas.c b/arch/powerpc/platforms/pseries/vas.c
> index df22827969db..4be80112b05e 100644
> --- a/arch/powerpc/platforms/pseries/vas.c
> +++ b/arch/powerpc/platforms/pseries/vas.c
> @@ -30,6 +30,7 @@ static struct hv_vas_cop_feat_caps hv_cop_caps;
>  
>  static struct vas_caps vascaps[VAS_MAX_FEAT_TYPE];
>  static DEFINE_MUTEX(vas_pseries_mutex);
> +static bool migration_in_progress;
>  
>  static long hcall_return_busy_check(long rc)
>  {
> @@ -356,8 +357,11 @@ static struct vas_window *vas_allocate_window(int vas_id, u64 flags,
>  	 * same fault IRQ is not freed by the OS before.
>  	 */
>  	mutex_lock(&vas_pseries_mutex);
> -	rc = allocate_setup_window(txwin, (u64 *)&domain[0],
> -				   cop_feat_caps->win_type);
> +	if (migration_in_progress)
> +		rc = -EBUSY;
> +	else
> +		rc = allocate_setup_window(txwin, (u64 *)&domain[0],
> +					   cop_feat_caps->win_type);
>  	mutex_unlock(&vas_pseries_mutex);
>  	if (rc)
>  		goto out;
> @@ -890,6 +894,11 @@ int vas_migration_handler(int action)
>  
>  	mutex_lock(&vas_pseries_mutex);
>  
> +	if (action == VAS_SUSPEND)
> +		migration_in_progress = true;
> +	else
> +		migration_in_progress = false;
> +
>  	for (i = 0; i < VAS_MAX_FEAT_TYPE; i++) {
>  		vcaps = &vascaps[i];
>  		caps = &vcaps->caps;
> -- 
> 2.27.0
> 
> 
>