Current code does:
- register pre_2_10_vmstate_dummy_icp with "icp/server" and instance
dependinfg on cpu number
- for newer machines, it register vmstate_icp with "icp/server" name
and instance 0
- now it unregisters "icp/server" for the 1st instance.
This is wrong at many levels:
- we shouldn't have two VMSTATEDescriptions with the same name
- In case this is the only solution that we can came with, it needs to
be:
* register pre_2_10_vmstate_dummy_icp
* unregister pre_2_10_vmstate_dummy_icp
* register real vmstate_icp
Created vmstate_replace_hack_for_ppc() with warnings left and right
that it is a hack.
CC: Cedric Le Goater <c...@kaod.org>
CC: Daniel Henrique Barboza <danielhb...@gmail.com>
CC: David Gibson <da...@gibson.dropbear.id.au>
CC: Greg Kurz <gr...@kaod.org>
Reviewed-by: Nicholas Piggin <npig...@gmail.com>
Signed-off-by: Juan Quintela <quint...@redhat.com>
Message-ID: <20231020090731.28701-8-quint...@redhat.com>
---
include/migration/vmstate.h | 11 +++++++++++
hw/intc/xics.c | 18 ++++++++++++++++--
hw/ppc/spapr.c | 25 +++++++++++++++++++++++--
migration/savevm.c | 18 ++++++++++++++++++
4 files changed, 68 insertions(+), 4 deletions(-)
diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
index 1ea97ccf2d..9821918631 100644
--- a/include/migration/vmstate.h
+++ b/include/migration/vmstate.h
@@ -1230,6 +1230,17 @@ static inline int vmstate_register(VMStateIf *obj, int
instance_id,
opaque, -1, 0, NULL);
}
+/**
+ * vmstate_replace_hack_for_ppc() - ppc used to abuse vmstate_register
+ *
+ * Don't even think about using this function in new code.
+ *
+ * Returns: 0 on success, -1 on failure
+ */
+int vmstate_replace_hack_for_ppc(VMStateIf *obj, int instance_id,
+ const VMStateDescription *vmsd,
+ void *opaque);
+
/**
* vmstate_register_any() - legacy function to register state
* serialisation description and let the function choose the id
diff --git a/hw/intc/xics.c b/hw/intc/xics.c
index c7f8abd71e..c77e986136 100644
--- a/hw/intc/xics.c
+++ b/hw/intc/xics.c
@@ -335,8 +335,22 @@ static void icp_realize(DeviceState *dev, Error **errp)
return;
}
}
-
- vmstate_register(NULL, icp->cs->cpu_index, &vmstate_icp_server, icp);
+ /*
+ * The way that pre_2_10_icp is handling is really, really hacky.
+ * We used to have here this call:
+ *
+ * vmstate_register(NULL, icp->cs->cpu_index, &vmstate_icp_server, icp);
+ *
+ * But we were doing:
+ * pre_2_10_vmstate_register_dummy_icp()
+ * this vmstate_register()
+ * pre_2_10_vmstate_unregister_dummy_icp()
+ *
+ * So for a short amount of time we had to vmstate entries with
+ * the same name. This fixes it.
+ */
+ vmstate_replace_hack_for_ppc(NULL, icp->cs->cpu_index,
+ &vmstate_icp_server, icp);
}
static void icp_unrealize(DeviceState *dev)
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index b25093be28..df09aa9d6a 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -143,6 +143,11 @@ static bool pre_2_10_vmstate_dummy_icp_needed(void *opaque)
}
static const VMStateDescription pre_2_10_vmstate_dummy_icp = {
+ /*
+ * Hack ahead. We can't have two devices with the same name and
+ * instance id. So I rename this to pass make check.
+ * Real help from people who knows the hardware is needed.
+ */
.name = "icp/server",
.version_id = 1,
.minimum_version_id = 1,
@@ -155,16 +160,32 @@ static const VMStateDescription
pre_2_10_vmstate_dummy_icp = {
},
};
+/*
+ * See comment in hw/intc/xics.c:icp_realize()
+ *
+ * You have to remove vmstate_replace_hack_for_ppc() when you remove
+ * the machine types that need the following function.
+ */
static void pre_2_10_vmstate_register_dummy_icp(int i)
{
vmstate_register(NULL, i, &pre_2_10_vmstate_dummy_icp,
(void *)(uintptr_t) i);
}
+/*
+ * See comment in hw/intc/xics.c:icp_realize()
+ *
+ * You have to remove vmstate_replace_hack_for_ppc() when you remove
+ * the machine types that need the following function.
+ */
static void pre_2_10_vmstate_unregister_dummy_icp(int i)
{
- vmstate_unregister(NULL, &pre_2_10_vmstate_dummy_icp,
- (void *)(uintptr_t) i);
+ /*
+ * This used to be:
+ *
+ * vmstate_unregister(NULL, &pre_2_10_vmstate_dummy_icp,
+ * (void *)(uintptr_t) i);
+ */
}
int spapr_max_server_number(SpaprMachineState *spapr)
diff --git a/migration/savevm.c b/migration/savevm.c
index ca5c7cebe0..1d1639c4b6 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -846,6 +846,24 @@ static void vmstate_check(const VMStateDescription *vmsd)
}
}
+/*
+ * See comment in hw/intc/xics.c:icp_realize()
+ *
+ * This function can be removed when
+ * pre_2_10_vmstate_register_dummy_icp() is removed.
+ */
+int vmstate_replace_hack_for_ppc(VMStateIf *obj, int instance_id,
+ const VMStateDescription *vmsd,
+ void *opaque)
+{
+ SaveStateEntry *se = find_se(vmsd->name, instance_id);
+
+ if (se) {
+ savevm_state_handler_remove(se);
+ }
+ return vmstate_register(obj, instance_id, vmsd, opaque);
+}
+
int vmstate_register_with_alias_id(VMStateIf *obj, uint32_t instance_id,
const VMStateDescription *vmsd,
void *opaque, int alias_id,
--
2.41.0
