From: Yanan Wang <wangyanan55@huawei.com>
To: <qemu-devel@nongnu.org>
Cc: "Peter Maydell" <peter.maydell@linaro.org>,
"Andrew Jones" <drjones@redhat.com>,
"Daniel P . Berrangé" <berrange@redhat.com>,
"Eduardo Habkost" <ehabkost@redhat.com>,
"Pierre Morel" <pmorel@linux.ibm.com>,
"Pankaj Gupta" <pankaj.gupta.linux@gmail.com>,
"Cornelia Huck" <cohuck@redhat.com>,
"Markus Armbruster" <armbru@redhat.com>,
"Yanan Wang" <wangyanan55@huawei.com>,
wanghaibin.wang@huawei.com, yuzenghui@huawei.com,
"Paolo Bonzini" <pbonzini@redhat.com>
Subject: [PATCH for-6.1 v2] machine: Disallow specifying topology parameters as zero
Date: Thu, 22 Jul 2021 23:43:26 +0800 [thread overview]
Message-ID: <20210722154326.1464-2-wangyanan55@huawei.com> (raw)
In-Reply-To: <20210722154326.1464-1-wangyanan55@huawei.com>
In the SMP configuration, we should either specify a topology
parameter with a reasonable value (equal to or greater than 1)
or just leave it omitted and QEMU will calculate its value.
Configurations which explicitly specify the topology parameters
as zero like "sockets=0" are meaningless, so disallow them.
However, the commit 1e63fe685804d
(machine: pass QAPI struct to mc->smp_parse) has documented that
'0' has the same semantics as omitting a parameter in the qapi
comment for SMPConfiguration. So this patch fixes the doc and
also adds the corresponding sanity check in the smp parsers.
Suggested-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
---
hw/core/machine.c | 14 ++++++++++++++
qapi/machine.json | 6 +++---
qemu-options.hx | 12 +++++++-----
3 files changed, 24 insertions(+), 8 deletions(-)
diff --git a/hw/core/machine.c b/hw/core/machine.c
index 775add0795..db129d937b 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -829,6 +829,20 @@ static void machine_set_smp(Object *obj, Visitor *v, const char *name,
return;
}
+ /*
+ * The topology parameters must be specified equal to or great than one
+ * or just omitted, 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)) {
+ error_setg(errp, "parameters must be equal to or greater than one if provided");
+ goto out_free;
+ }
+
mc->smp_parse(ms, config, errp);
if (errp) {
goto out_free;
diff --git a/qapi/machine.json b/qapi/machine.json
index c3210ee1fb..9272cb3cf8 100644
--- a/qapi/machine.json
+++ b/qapi/machine.json
@@ -1288,8 +1288,8 @@
##
# @SMPConfiguration:
#
-# Schema for CPU topology configuration. "0" or a missing value lets
-# QEMU figure out a suitable value based on the ones that are provided.
+# Schema for CPU topology configuration. A missing value lets QEMU
+# figure out a suitable value based on the ones that are provided.
#
# @cpus: number of virtual CPUs in the virtual machine
#
@@ -1297,7 +1297,7 @@
#
# @dies: number of dies per socket in the CPU topology
#
-# @cores: number of cores per thread in the CPU topology
+# @cores: number of cores per die in the CPU topology
#
# @threads: number of threads per core in the CPU topology
#
diff --git a/qemu-options.hx b/qemu-options.hx
index 99ed5ec5f1..b0168f8c48 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -223,11 +223,13 @@ 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 equal to or great
+ than one, 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,
--
2.19.1
next prev parent reply other threads:[~2021-07-22 15:46 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-22 15:43 [PATCH for-6.1 v2 0/1] machine: Disallow specifying topology parameters as zero Yanan Wang
2021-07-22 15:43 ` Yanan Wang [this message]
2021-07-22 16:01 ` [PATCH for-6.1 v2] " Daniel P. Berrangé
2021-07-23 8:02 ` Markus Armbruster
2021-07-23 8:40 ` wangyanan (Y)
2021-07-23 8:46 ` Cornelia Huck
2021-07-22 16:15 ` Andrew Jones
2021-07-22 22:25 ` Cleber Rosa
2021-07-23 1:57 ` wangyanan (Y)
2021-07-23 14:14 ` Cleber Rosa
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