[PATCH v2] powerpc/pseries/vas: Ignore VAS update for DLPAR if copy/paste is not enabled

[Nathan Lynch]

Haren Myneni <haren at linux.ibm.com> writes:
> The hypervisor supports user-mode NX from Power10. pseries_vas_dlpar_cpu()
> is called from lparcfg_write() to update VAS windows for DLPAR event in
> shared processor mode and the kernel gets -ENOTSUPP for HCALLs if the
> user-mode NX is not supported. The current VAS implementation also
> supports only with Radix page tables. Whereas in dedicated processor
> mode, pseries_vas_notifier() is registered only if the copy/paste
> feature is enabled. So instead of displaying HCALL error messages,
> update VAS capabilities if the copy/paste feature is available.

OK, so this prevents the code from making inappropriate hcalls and
logging useless errors, looks good.

>
> This patch ignores updating VAS capabilities in pseries_vas_dlpar_cpu()
> and returns success if the copy/paste feature is not enabled.
> Then lparcfg_write() completes the processor DLPAR operations
> without any failures.
>
> Fixes: 2147783d6bf0 ("powerpc/pseries: Use lparcfg to reconfig VAS windows for DLPAR CPU")
> Signed-off-by: Haren Myneni <haren at linux.ibm.com>

Reviewed-by: Nathan Lynch <nathanl at linux.ibm.com>


> ---
> v2: Use bool for copypaste_feat and expand commit message on handling failures
>
>  arch/powerpc/platforms/pseries/vas.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/arch/powerpc/platforms/pseries/vas.c b/arch/powerpc/platforms/pseries/vas.c
> index 559112312810..513180467562 100644
> --- a/arch/powerpc/platforms/pseries/vas.c
> +++ b/arch/powerpc/platforms/pseries/vas.c
> @@ -856,6 +856,13 @@ int pseries_vas_dlpar_cpu(void)
>  {
>  	int new_nr_creds, rc;
>  
> +	/*
> +	 * NX-GZIP is not enabled. Nothing to do for DLPAR event
> +	 */
> +	if (!copypaste_feat)
> +		return 0;
> +
> +
>  	rc = h_query_vas_capabilities(H_QUERY_VAS_CAPABILITIES,
>  				      vascaps[VAS_GZIP_DEF_FEAT_TYPE].feat,
>  				      (u64)virt_to_phys(&hv_cop_caps));
> @@ -1012,6 +1019,7 @@ static int __init pseries_vas_init(void)
>  	 * Linux supports user space COPY/PASTE only with Radix
>  	 */
>  	if (!radix_enabled()) {
> +		copypaste_feat = false;
>  		pr_err("API is supported only with radix page tables\n");
>  		return -ENOTSUPP;
>  	}
> -- 
> 2.26.3