[RFC PATCH 2/3] powerpc/pseries/vas: Add VAS suspend/resume notifier

[Haren Myneni <haren@linux.ibm.com>]

Since the windows belong to the VAS hardware resource, the
hypervisor expects the partition to close them on source partition
and reopen them after the partition migrated on the destination
machine.

This suspend/resume notifier invokes suspend operation before
and resume operation after migration. All active windows for
both default and QoS types will be closed during suspend and
reopen them during resume. During migration, the user space
should expect paste instruction failure if issues copy/paste
on these active windows.

Signed-off-by: Haren Myneni <haren@linux.ibm.com>
---
 arch/powerpc/platforms/pseries/vas.c | 97 +++++++++++++++++++++++++++-
 1 file changed, 96 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/pseries/vas.c b/arch/powerpc/platforms/pseries/vas.c
index e4797fc73553..7087528e4246 100644
--- a/arch/powerpc/platforms/pseries/vas.c
+++ b/arch/powerpc/platforms/pseries/vas.c
@@ -16,6 +16,7 @@
 #include <asm/machdep.h>
 #include <asm/hvcall.h>
 #include <asm/plpar_wrappers.h>
+#include <asm/pseries-suspend.h>
 #include <asm/vas.h>
 #include "vas.h"
 
@@ -873,6 +874,98 @@ static struct notifier_block pseries_vas_nb = {
 	.notifier_call = pseries_vas_notifier,
 };
 
+/*
+ * For LPM, all windows have to be closed on the source partition
+ * before migration and reopen them on the destination partition
+ * after migration. So closing windows during suspend and
+ * reopen them during resume.
+ */
+static int vas_migrate_windows(bool suspend)
+{
+	struct hv_vas_cop_feat_caps *hv_caps;
+	struct vas_cop_feat_caps *caps;
+	int lpar_creds, new_creds = 0;
+	struct vas_caps *vcaps;
+	int i, rc = 0;
+
+	hv_caps = kmalloc(sizeof(*hv_caps), GFP_KERNEL);
+	if (!hv_caps)
+		return -ENOMEM;
+
+	mutex_lock(&vas_pseries_mutex);
+
+	for (i = 0; i < VAS_MAX_FEAT_TYPE; i++) {
+		vcaps = &vascaps[i];
+		caps = &vcaps->caps;
+		lpar_creds = atomic_read(&caps->target_creds);
+
+		rc = h_query_vas_capabilities(H_QUERY_VAS_CAPABILITIES, vcaps->feat,
+									(u64)virt_to_phys(hv_caps));
+		if (!rc) {
+			new_creds = be16_to_cpu(hv_caps->target_lpar_creds);
+			/*
+			 * Should not happen. But incase print messages, close all
+			 * windows in the list during suspend and reopen windows
+			 * based on new lpar_creds on the destination system.
+			 */
+			if (lpar_creds != new_creds) {
+				pr_err("%s: lpar creds: %d HV lpar creds: %d\n",
+						suspend ? "Suspend" : "Resume", lpar_creds,
+						new_creds);
+				pr_err("Used creds: %d, Active creds: %d\n",
+						atomic_read(&caps->used_creds),
+						vcaps->num_wins - vcaps->close_wins);
+			}
+		} else {
+			pr_err("%s: Get VAS capabilities failed with %d\n",
+					suspend ? "Suspend" : "Resume", rc);
+			/*
+			 * We can not stop migration with the current lpm
+			 * implementation. So continue closing all windows in the
+			 * list (during suspend) and return without opending windows
+			 * (during resume) if VAS capabilities HCALL failed.
+			 */
+			if (!suspend)
+				goto out;
+		}
+
+		if (suspend)
+			rc = reconfig_close_windows(vcaps, vcaps->num_wins, true);
+		else {
+			atomic_set(&caps->target_creds, new_creds);
+			rc = reconfig_open_windows(vcaps, new_creds, true);
+		}
+
+		/*
+		 * Ignore errors during suspend and return for resume.
+		 */
+		if (rc && !suspend)
+			goto out;
+	}
+
+out:
+	mutex_unlock(&vas_pseries_mutex);
+	kfree(hv_caps);
+	return rc;
+}
+
+static int vas_migration_handler(struct notifier_block *nb,
+								 unsigned long action, void *data)
+{
+	if (action == PSERIES_RESUMING)
+		return vas_migrate_windows(false);
+	else
+		return vas_migrate_windows(true);
+
+}
+
+static struct pseries_suspend_handler vas_suspend_handler = {
+	.notifier_block = {
+		.notifier_call = vas_migration_handler,
+	},
+};
+
+
 static int __init pseries_vas_init(void)
 {
 	struct hv_vas_cop_feat_caps *hv_cop_caps;
@@ -929,8 +1022,10 @@ static int __init pseries_vas_init(void)
 	}
 
 	/* Processors can be added/removed only on LPAR */
-	if (copypaste_feat && firmware_has_feature(FW_FEATURE_LPAR))
+	if (copypaste_feat && firmware_has_feature(FW_FEATURE_LPAR)) {
 		of_reconfig_notifier_register(&pseries_vas_nb);
+		pseries_register_suspend_handler(&vas_suspend_handler);
+	}
 
 	pr_info("GZIP feature is available\n");
 
-- 
2.27.0