On 2/1/23 14:20, Pierre Morel wrote:
The modification of the CPU attributes are done through a monitor
command.
It allows to move the core inside the topology tree to optimise
the cache usage in the case the host's hypervisor previously
moved the CPU.
The same command allows to modify the CPU attributes modifiers
like polarization entitlement and the dedicated attribute to notify
the guest if the host admin modified scheduling or dedication of a vCPU.
With this knowledge the guest has the possibility to optimize the
usage of the vCPUs.
The command is made experimental for the moment.
Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
---
qapi/machine-target.json | 29 +++++++++++++
include/monitor/hmp.h | 1 +
hw/s390x/cpu-topology.c | 88 ++++++++++++++++++++++++++++++++++++++++
hmp-commands.hx | 16 ++++++++
4 files changed, 134 insertions(+)
diff --git a/qapi/machine-target.json b/qapi/machine-target.json
index 2e267fa458..58df0f5061 100644
--- a/qapi/machine-target.json
+++ b/qapi/machine-target.json
@@ -342,3 +342,32 @@
'TARGET_S390X',
'TARGET_MIPS',
'TARGET_LOONGARCH64' ] } }
+
+##
+# @x-set-cpu-topology:
+#
+# @core: the vCPU ID to be moved
+# @socket: the destination socket where to move the vCPU
+# @book: the destination book where to move the vCPU
+# @drawer: the destination drawer where to move the vCPU
+# @polarity: optional polarity, default is last polarity set by the guest
+# @dedicated: optional, if the vCPU is dedicated to a real CPU
+#
+# Modifies the topology by moving the CPU inside the topology
+# tree or by changing a modifier attribute of a CPU.
+#
+# Returns: Nothing on success, the reason on failure.
+#
+# Since: <next qemu stable release, eg. 1.0>
+##
+{ 'command': 'x-set-cpu-topology',
+ 'data': {
+ 'core': 'int',
+ 'socket': 'int',
+ 'book': 'int',
+ 'drawer': 'int',
+ '*polarity': 'int',
+ '*dedicated': 'bool'
+ },
+ 'if': { 'all': [ 'TARGET_S390X', 'CONFIG_KVM' ] }
+}
diff --git a/include/monitor/hmp.h b/include/monitor/hmp.h
index 1b3bdcb446..12827479cf 100644
--- a/include/monitor/hmp.h
+++ b/include/monitor/hmp.h
@@ -151,5 +151,6 @@ void hmp_human_readable_text_helper(Monitor *mon,
HumanReadableText *(*qmp_handler)(Error **));
void hmp_info_stats(Monitor *mon, const QDict *qdict);
void hmp_pcie_aer_inject_error(Monitor *mon, const QDict *qdict);
+void hmp_x_set_cpu_topology(Monitor *mon, const QDict *qdict);
#endif
diff --git a/hw/s390x/cpu-topology.c b/hw/s390x/cpu-topology.c
index c33378577b..6c50050991 100644
--- a/hw/s390x/cpu-topology.c
+++ b/hw/s390x/cpu-topology.c
@@ -18,6 +18,10 @@
#include "target/s390x/cpu.h"
#include "hw/s390x/s390-virtio-ccw.h"
#include "hw/s390x/cpu-topology.h"
+#include "qapi/qapi-commands-machine-target.h"
+#include "qapi/qmp/qdict.h"
+#include "monitor/hmp.h"
+#include "monitor/monitor.h"
/*
* s390_topology is used to keep the topology information.
@@ -379,3 +383,87 @@ void s390_topology_set_cpu(MachineState *ms, S390CPU *cpu, Error **errp)
/* topology tree is reflected in props */
s390_update_cpu_props(ms, cpu);
}
+
+/*
+ * qmp and hmp implementations
+ */
+
+static void s390_change_topology(int64_t core_id, int64_t socket_id,
+ int64_t book_id, int64_t drawer_id,
+ int64_t polarity, bool dedicated,
+ Error **errp)
+{
+ MachineState *ms = current_machine;
+ S390CPU *cpu;
+ ERRP_GUARD();
+
+ cpu = (S390CPU *)ms->possible_cpus->cpus[core_id].cpu;
+ if (!cpu) {
+ error_setg(errp, "Core-id %ld does not exist!", core_id);
+ return;
+ }
+
+ /* Verify the new topology */
!! Should verify the new topology but ...
+ s390_topology_check(cpu, errp);
... verifies the old one => I will have to change this.
Sorry, this will impact the patch 2 because I think I should modify the
s390_topology_check() function to take as arguments the individual
attributes.
Like:
static void s390_topology_check( uint16_t core_id, uint16_t socket_id,
uint16_t book_id, uint16_t drawer_id,
uint16_t entitlement, bool dedicated,
Error **errp)
Regards,
Pierre
--
Pierre Morel
IBM Lab Boeblingen
