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

[Haren Myneni]

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.

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>
---
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