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[PULL 02/30] machine: Deprecate "parameter=0" SMP configurations
From: |
Paolo Bonzini |
Subject: |
[PULL 02/30] machine: Deprecate "parameter=0" SMP configurations |
Date: |
Sun, 3 Oct 2021 09:42:22 +0200 |
From: Yanan Wang <wangyanan55@huawei.com>
In the SMP configuration, we should either provide a topology
parameter with a reasonable value (greater than zero) or just
omit it and QEMU will compute the missing value.
The users shouldn't provide a configuration with any parameter
of it specified as zero (e.g. -smp 8,sockets=0) which could
possibly cause unexpected results in the -smp parsing. So we
deprecate this kind of configurations since 6.2 by adding the
explicit sanity check.
Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20210929025816.21076-3-wangyanan55@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
docs/about/deprecated.rst | 15 +++++++++++++++
hw/core/machine.c | 14 ++++++++++++++
qemu-options.hx | 12 +++++++-----
3 files changed, 36 insertions(+), 5 deletions(-)
diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst
index 2f7db9a98d..0bed6ecb1d 100644
--- a/docs/about/deprecated.rst
+++ b/docs/about/deprecated.rst
@@ -160,6 +160,21 @@ Use ``-display sdl`` instead.
Use ``-display curses`` instead.
+``-smp`` ("parameter=0" SMP configurations) (since 6.2)
+'''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+Specified CPU topology parameters must be greater than zero.
+
+In the SMP configuration, users should either provide a CPU topology
+parameter with a reasonable value (greater than zero) or just omit it
+and QEMU will compute the missing value.
+
+However, historically it was implicitly allowed for users to provide
+a parameter with zero value, which is meaningless and could also possibly
+cause unexpected results in the -smp parsing. So support for this kind of
+configurations (e.g. -smp 8,sockets=0) is deprecated since 6.2 and will
+be removed in the near future, users have to ensure that all the topology
+members described with -smp are greater than zero.
Plugin argument passing through ``arg=<string>`` (since 6.1)
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
diff --git a/hw/core/machine.c b/hw/core/machine.c
index 067f42b528..4e409261c9 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -835,6 +835,20 @@ static void machine_set_smp(Object *obj, Visitor *v, const
char *name,
return;
}
+ /*
+ * Specified CPU topology parameters must be greater than zero,
+ * explicit configuration like "cpus=0" is not allowed.
+ */
+ if ((config->has_cpus && config->cpus == 0) ||
+ (config->has_sockets && config->sockets == 0) ||
+ (config->has_dies && config->dies == 0) ||
+ (config->has_cores && config->cores == 0) ||
+ (config->has_threads && config->threads == 0) ||
+ (config->has_maxcpus && config->maxcpus == 0)) {
+ warn_report("Deprecated CPU topology (considered invalid): "
+ "CPU topology parameters must be greater than zero");
+ }
+
mc->smp_parse(ms, config, errp);
if (*errp) {
goto out_free;
diff --git a/qemu-options.hx b/qemu-options.hx
index ceca52818a..4a092a092a 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -233,11 +233,13 @@ SRST
of computing the CPU maximum count.
Either the initial CPU count, or at least one of the topology parameters
- must be specified. Values for any omitted parameters will be computed
- from those which are given. Historically preference was given to the
- coarsest topology parameters when computing missing values (ie sockets
- preferred over cores, which were preferred over threads), however, this
- behaviour is considered liable to change.
+ must be specified. The specified parameters must be greater than zero,
+ explicit configuration like "cpus=0" is not allowed. Values for any
+ omitted parameters will be computed from those which are given.
+ Historically preference was given to the coarsest topology parameters
+ when computing missing values (ie sockets preferred over cores, which
+ were preferred over threads), however, this behaviour is considered
+ liable to change.
ERST
DEF("numa", HAS_ARG, QEMU_OPTION_numa,
--
2.31.1
- [PULL 00/30] Misc changes for 2021-10-03, Paolo Bonzini, 2021/10/03
- [PULL 01/30] qapi/machine: Fix an incorrect comment of SMPConfiguration, Paolo Bonzini, 2021/10/03
- [PULL 03/30] machine: Minor refactor/fix for the smp parsers, Paolo Bonzini, 2021/10/03
- [PULL 02/30] machine: Deprecate "parameter=0" SMP configurations,
Paolo Bonzini <=
- [PULL 05/30] machine: Set the value of cpus to match maxcpus if it's omitted, Paolo Bonzini, 2021/10/03
- [PULL 04/30] machine: Uniformly use maxcpus to calculate the omitted parameters, Paolo Bonzini, 2021/10/03
- [PULL 06/30] machine: Improve the error reporting of smp parsing, Paolo Bonzini, 2021/10/03
- [PULL 09/30] machine: Prefer cores over sockets in smp parsing since 6.2, Paolo Bonzini, 2021/10/03
- [PULL 08/30] qtest/numa-test: Use detailed -smp CLIs in test_def_cpu_split, Paolo Bonzini, 2021/10/03
- [PULL 07/30] qtest/numa-test: Use detailed -smp CLIs in pc_dynamic_cpu_cfg, Paolo Bonzini, 2021/10/03
- [PULL 11/30] machine: Tweak the order of topology members in struct CpuTopology, Paolo Bonzini, 2021/10/03
- [PULL 12/30] machine: Make smp_parse generic enough for all arches, Paolo Bonzini, 2021/10/03
- [PULL 10/30] machine: Use ms instead of global current_machine in sanity-check, Paolo Bonzini, 2021/10/03
- [PULL 13/30] machine: Remove smp_parse callback from MachineClass, Paolo Bonzini, 2021/10/03