From 35f06623b82d99dd380340eef465394975dd1c80 Mon Sep 17 00:00:00 2001
Message-Id: <35f06623b82d99dd380340eef465394975dd1c80@dist-git>
From: Jiri Denemark <jdenemar@redhat.com>
Date: Wed, 22 Jun 2022 16:37:31 +0200
Subject: [PATCH] qemu_migration: Implement VIR_MIGRATE_ZEROCOPY flag
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Resolves: https://gitlab.com/libvirt/libvirt/-/issues/306
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
(cherry picked from commit d375993ab314a41bca7ef6c846e07afc18c37774)
https://bugzilla.redhat.com/show_bug.cgi?id=2089433
Conflicts:
src/qemu/qemu_migration.c
src/qemu/qemu_migration.h
- post-copy recovery not bacported
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
---
src/qemu/qemu_migration.c | 21 +++++++++++++++++++++
src/qemu/qemu_migration.h | 1 +
src/qemu/qemu_migration_params.c | 6 ++++++
src/qemu/qemu_migration_params.h | 1 +
4 files changed, 29 insertions(+)
diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index 35ad201580..db5163e993 100644
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -2366,6 +2366,12 @@ qemuMigrationSrcBeginPhase(virQEMUDriver *driver,
return NULL;
}
+ if (flags & VIR_MIGRATE_ZEROCOPY && !(flags & VIR_MIGRATE_PARALLEL)) {
+ virReportError(VIR_ERR_OPERATION_INVALID, "%s",
+ _("zero-copy is only available for parallel migration"));
+ return NULL;
+ }
+
if (flags & (VIR_MIGRATE_NON_SHARED_DISK | VIR_MIGRATE_NON_SHARED_INC)) {
if (flags & VIR_MIGRATE_NON_SHARED_SYNCHRONOUS_WRITES &&
!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BLOCKDEV)) {
@@ -4137,6 +4143,21 @@ qemuMigrationSrcRun(virQEMUDriver *driver,
migParams) < 0)
goto error;
+ if (flags & VIR_MIGRATE_ZEROCOPY) {
+ /* Zero-copy requires pages in transfer to be locked in host memory.
+ * Unfortunately, we have no reliable way of computing how many pages
+ * will need to be locked at the same time. Thus we set the limit to
+ * the whole guest memory and reset it back once migration is done. */
+ unsigned long long limit;
+
+ if (virMemoryLimitIsSet(vm->def->mem.hard_limit))
+ limit = vm->def->mem.hard_limit;
+ else
+ limit = virDomainDefGetMemoryTotal(vm->def);
+
+ if (qemuDomainSetMaxMemLock(vm, limit << 10, &priv->preMigrationMemlock) < 0)
+ goto error;
+ }
if (storageMigration) {
if (mig->nbd) {
diff --git a/src/qemu/qemu_migration.h b/src/qemu/qemu_migration.h
index b233358a51..6f737f7b4c 100644
--- a/src/qemu/qemu_migration.h
+++ b/src/qemu/qemu_migration.h
@@ -60,6 +60,7 @@
VIR_MIGRATE_TLS | \
VIR_MIGRATE_PARALLEL | \
VIR_MIGRATE_NON_SHARED_SYNCHRONOUS_WRITES | \
+ VIR_MIGRATE_ZEROCOPY | \
0)
/* All supported migration parameters and their types. */
diff --git a/src/qemu/qemu_migration_params.c b/src/qemu/qemu_migration_params.c
index 7b225fdf4b..c985583861 100644
--- a/src/qemu/qemu_migration_params.c
+++ b/src/qemu/qemu_migration_params.c
@@ -96,6 +96,7 @@ VIR_ENUM_IMPL(qemuMigrationCapability,
"multifd",
"dirty-bitmaps",
"return-path",
+ "zero-copy-send",
);
@@ -177,6 +178,11 @@ static const qemuMigrationParamsFlagMapItem qemuMigrationParamsFlagMap[] = {
VIR_MIGRATE_TUNNELLED,
QEMU_MIGRATION_CAP_RETURN_PATH,
QEMU_MIGRATION_SOURCE | QEMU_MIGRATION_DESTINATION},
+
+ {QEMU_MIGRATION_FLAG_REQUIRED,
+ VIR_MIGRATE_ZEROCOPY,
+ QEMU_MIGRATION_CAP_ZERO_COPY_SEND,
+ QEMU_MIGRATION_SOURCE},
};
/* Translation from VIR_MIGRATE_PARAM_* typed parameters to
diff --git a/src/qemu/qemu_migration_params.h b/src/qemu/qemu_migration_params.h
index b4de8dda7b..caa5e47f0f 100644
--- a/src/qemu/qemu_migration_params.h
+++ b/src/qemu/qemu_migration_params.h
@@ -41,6 +41,7 @@ typedef enum {
QEMU_MIGRATION_CAP_MULTIFD,
QEMU_MIGRATION_CAP_BLOCK_DIRTY_BITMAPS,
QEMU_MIGRATION_CAP_RETURN_PATH,
+ QEMU_MIGRATION_CAP_ZERO_COPY_SEND,
QEMU_MIGRATION_CAP_LAST
} qemuMigrationCapability;
--
2.35.1