[RFC PATCH 3/3] powerpc/pseries/vas: Disable window open during migration

[Haren Myneni]

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 | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/vas.c b/arch/powerpc/platforms/pseries/vas.c
index 7087528e4246..e407767a9cb8 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)
 {
@@ -356,8 +357,11 @@ 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;
@@ -796,6 +800,7 @@ int vas_reconfig_capabilties(u8 type)
 		return -ENOMEM;
 
 	mutex_lock(&vas_pseries_mutex);
+
 	rc = h_query_vas_capabilities(H_QUERY_VAS_CAPABILITIES, vcaps->feat,
 				      (u64)virt_to_phys(hv_caps));
 	if (rc)
@@ -894,6 +899,11 @@ 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