If a given machine have max_cpus set, not just smp_cpus needs to be
limited, but the total number of CPUs (considering CPU hotplug) for the
machine.
We also had yet another max_cpus limit check at smp_parse(), ensuring
that max_cpus < MAX_CPUMASK_BITS.
This patch unifies the machine->max_cpus and MAX_CPUMASK_BITS checks,
and also moves the (smp_cpus <= max_cpus) outside smp_parse(), to keep
all checks in the same place.
With those changes, the new code ensures that:
1 <= smp_cpus <= max_cpus <= machine->max_cpus <= MAX_CPUMASK_BITS
Signed-off-by: Eduardo Habkost <ehabk...@redhat.com>
Cc: Peter Maydell <peter.mayd...@linaro.org>
Cc: Andreas Färber <afaer...@suse.de>
Cc: Igor Mammedov <imamm...@redhat.com>
Cc: Marcelo Tosatti <mtosa...@redhat.com>
---
Changes v1 -> v2:
* v1 was: [PATCH] vl.c: Check max_cpus limit instead of smp_cpus
* Unify machine->max_cpus and MAX_CPUMASK_BITS check
* Move all checks outside smp_parse()
* Add assert() lines ensuring the results are consistent
* s/machine/machine_class/, after rebase to latest qemu.git
(commit 6b342cc)
---
vl.c | 26 ++++++++++++++------------
1 file changed, 14 insertions(+), 12 deletions(-)
diff --git a/vl.c b/vl.c
index 73e0661..434cdc3 100644
--- a/vl.c
+++ b/vl.c
@@ -1425,15 +1425,6 @@ static void smp_parse(QemuOpts *opts)
max_cpus = smp_cpus;
}
- if (max_cpus > MAX_CPUMASK_BITS) {
- fprintf(stderr, "Unsupported number of maxcpus\n");
- exit(1);
- }
- if (max_cpus < smp_cpus) {
- fprintf(stderr, "maxcpus must be equal to or greater than smp\n");
- exit(1);
- }
-
}
static void configure_realtime(QemuOpts *opts)
@@ -4055,13 +4046,24 @@ int main(int argc, char **argv, char **envp)
smp_parse(qemu_opts_find(qemu_find_opts("smp-opts"), NULL));
machine_class->max_cpus = machine_class->max_cpus ?: 1; /* Default to UP */
- if (smp_cpus > machine_class->max_cpus) {
- fprintf(stderr, "Number of SMP cpus requested (%d), exceeds max cpus "
- "supported by machine `%s' (%d)\n", smp_cpus,
+ machine_class->max_cpus = MIN(machine_class->max_cpus, MAX_CPUMASK_BITS);
+
+ if (max_cpus < smp_cpus) {
+ fprintf(stderr, "maxcpus must be equal to or greater than smp\n");
+ exit(1);
+ }
+ if (max_cpus > machine_class->max_cpus) {
+ fprintf(stderr, "Total number of CPUs (%d), exceeds maximum "
+ "supported by machine `%s' (%d)\n", max_cpus,
machine_class->name, machine_class->max_cpus);
exit(1);
}
+ assert(1 <= smp_cpus);
+ assert(smp_cpus <= max_cpus);
+ assert(max_cpus <= machine_class->max_cpus);
+ assert(machine_class->max_cpus <= MAX_CPUMASK_BITS);
+
/*
* Get the default machine options from the machine if it is not already
* specified either by the configuration file or by the command line.
--
1.9.0
