[RFC PATCH 3/3] powerpc/pseries/vas: Use migration_in_progress to disable DLPAR

[Haren Myneni]

Before migration starts, all secondary CPUs will be offline which
can invoke VAS DLPAR event. So disable VAS DLPAR event with
migration_in_progress flag during suspend and enable after resume
operations.

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.

Signed-off-by: Haren Myneni <haren at linux.ibm.com>
---
 arch/powerpc/platforms/pseries/vas.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/vas.c b/arch/powerpc/platforms/pseries/vas.c
index d2d7202a4f4e..1a10c1904aaa 100644
--- a/arch/powerpc/platforms/pseries/vas.c
+++ b/arch/powerpc/platforms/pseries/vas.c
@@ -30,6 +30,7 @@ static bool copypaste_feat;
 
 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)
 {
@@ -349,8 +350,11 @@ 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;
@@ -771,6 +775,9 @@ int vas_reconfig_capabilties(u8 type)
 		return -ENOMEM;
 
 	mutex_lock(&vas_pseries_mutex);
+	if (migration_in_progress)
+		goto out;
+
 	rc = h_query_vas_capabilities(H_QUERY_VAS_CAPABILITIES, vcaps->feat,
 				      (u64)virt_to_phys(hv_caps));
 	if (rc)
@@ -866,6 +873,11 @@ static int vas_migrate_windows(bool suspend)
 
 	mutex_lock(&vas_pseries_mutex);
 
+	if (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