On Tue, 2023-03-07 at 20:55 -0600, Nathan Lynch wrote: > Haren Myneni <ha...@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 CPU > > event > > and the kernel gets -ENOTSUPP for HCALLs if the user-mode NX is not > > supported. > > The commit text would be improved by more explanation about the > higher > level failure mode here. Does lparcfg_write() fail when it shouldn't? > If > so, does that cause a processor DLPAR operation to spuriously fail?
Thanks for your suggestions, I will add more explanation in the description. Even if copy/paste is not enabled, pseries_vas_dlpar_cpu() just returns 0 which allows lparcfg_write() returns success - will not affect DLPAR operation. if (pseries_vas_dlpar_cpu() != 0) retval = H_HARDWARE; > > pseries_vas_dlpar_cpu() is also called from pseries_vas_notifier() in > dedicated processor mode. Does this problem affect that scenario > also? It should not affect for dedicated processor mode. pseries_vas_notifier() is registered if copy/paste is enabled. if (!rc && copypaste_feat) { if (firmware_has_feature(FW_FEATURE_LPAR)) of_reconfig_notifier_register(&pseries_vas_nb); > > > This patch ignores updating VAS capabilities and returns success if > > the > > copy/paste feature is not enabled. > > > > Fixes: 2147783d6bf0 ("powerpc/pseries: Use lparcfg to reconfig VAS > > windows for DLPAR CPU") > > Signed-off-by: Haren Myneni <ha...@linux.ibm.com> > > --- > > 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..dc003849d2c5 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].f > > eat, > > (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 = 0; > > copypaste_feat is a bool, so use false, not 0. But otherwise I think > this looks correct and consistent with the rest of the code in vas.c. Correct my mistake. Thanks Haren