linux-kernel - [PATCH 1/2] powerpc/mobility: Wait for memory transfer to complete

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Message-Id: <20220601155315.35109-2-ldufour@linux.ibm.com>
Date:   Wed,  1 Jun 2022 17:53:14 +0200
From:   Laurent Dufour <ldufour@...ux.ibm.com>
To:     mpe@...erman.id.au, benh@...nel.crashing.org, paulus@...ba.org,
        nathanl@...ux.ibm.com, haren@...ux.vnet.ibm.com, npiggin@...il.com
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] powerpc/mobility: Wait for memory transfer to complete

In pseries_migration_partition(), loop until the memory transfer is
complete. This way the calling drmgr process will not exit earlier,
allowing callbacks to be run only once the migration is fully completed.

This will also allow to manage the NMI watchdog state in the next commits.

Signed-off-by: Laurent Dufour <ldufour@...ux.ibm.com>
---
 arch/powerpc/platforms/pseries/mobility.c | 34 +++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
index 78f3f74c7056..55612a1b07d6 100644
--- a/arch/powerpc/platforms/pseries/mobility.c
+++ b/arch/powerpc/platforms/pseries/mobility.c
@@ -427,6 +427,35 @@ static int wait_for_vasi_session_suspending(u64 handle)
 	return ret;
 }
 
+static void wait_for_vasi_session_completed(u64 handle)
+{
+	unsigned long state = 0;
+	int ret;
+
+	pr_info("waiting for memory transfert to complete...\n");
+	/*
+	 * Wait for transition from H_VASI_RESUMED to
+	 * H_VASI_COMPLETED. Treat anything else as an error.
+	 */
+	while (true) {
+		ret = poll_vasi_state(handle, &state);
+
+		if (ret || state == H_VASI_COMPLETED)
+			break;
+
+		if (state != H_VASI_RESUMED) {
+			pr_err("unexpected H_VASI_STATE result %lu\n", state);
+			ret = -EIO;
+			break;
+		}
+
+		msleep(500);
+	}
+
+	pr_info("memory transfert completed (ret:%d state:%ld).\n",
+		ret, state);
+}
+
 static void prod_single(unsigned int target_cpu)
 {
 	long hvrc;
@@ -673,9 +702,10 @@ static int pseries_migrate_partition(u64 handle)
 	vas_migration_handler(VAS_SUSPEND);
 
 	ret = pseries_suspend(handle);
-	if (ret == 0)
+	if (ret == 0) {
 		post_mobility_fixup();
-	else
+		wait_for_vasi_session_completed(handle);
+	} else
 		pseries_cancel_migration(handle, ret);
 
 	vas_migration_handler(VAS_RESUME);
-- 
2.36.1