| Message ID | 1343672558-8560-1-git-send-email-riegamaths@gmail.com |
|---|---|
| State | New |
| Headers | show |
On Mon, Jul 30, 2012 at 7:22 PM, <riegamaths@gmail.com> wrote: > From: Dunrong Huang <riegamaths@gmail.com> > > Add a helper function for fetching max cpus supported by kvm. > > Make QEMU exit with an error message if smp_cpus exceeds limit > of VCPU count retrieved by invoking this helper function. > > Signed-off-by: Dunrong Huang <riegamaths@gmail.com> > --- > kvm-all.c | 25 +++++++++++++++++++++++++ > 1 files changed, 25 insertions(+), 0 deletions(-) > > diff --git a/kvm-all.c b/kvm-all.c > index 2148b20..8cb4b92 100644 > --- a/kvm-all.c > +++ b/kvm-all.c > @@ -1207,6 +1207,23 @@ static int kvm_irqchip_create(KVMState *s) > return 0; > } > > +static int kvm_max_vcpus(KVMState *s) > +{ > + int max_vcpus = 4; > + int ret; > + ret = kvm_check_extension(s, KVM_CAP_MAX_VCPUS); > + if (ret) { > + max_vcpus = ret; > + } else { > + ret = kvm_check_extension(s, KVM_CAP_NR_VCPUS); > + if (ret) { > + max_vcpus = ret; > + } > + } The indentation is off here. It should be 4 spaces. Otherwise looks fine. Stefan
On 30 July 2012 19:22, <riegamaths@gmail.com> wrote: > +static int kvm_max_vcpus(KVMState *s) > +{ > + int max_vcpus = 4; > + int ret; > + ret = kvm_check_extension(s, KVM_CAP_MAX_VCPUS); > + if (ret) { > + max_vcpus = ret; > + } else { > + ret = kvm_check_extension(s, KVM_CAP_NR_VCPUS); > + if (ret) { > + max_vcpus = ret; > + } > + } > + > + return max_vcpus; > +} A small thing, but I think having code flow like: /* Find number of supported CPUs using the recommended * procedure from the kernel API documentation to cope with * older kernels that may be missing capabilities. */ ret = kvm_check_extension(s, KVM_CAP_MAX_VCPUS); if (ret) { return ret; } ret = kvm_check_extension(s, KVM_CAP_NR_VCPUS); if (ret) { return ret; } return 4; would be clearer. (also I think a comment helps suggest that 4 isn't a magic number we made up ourselves :-)) -- PMM
diff --git a/kvm-all.c b/kvm-all.c index 2148b20..8cb4b92 100644 --- a/kvm-all.c +++ b/kvm-all.c @@ -1207,6 +1207,23 @@ static int kvm_irqchip_create(KVMState *s) return 0; } +static int kvm_max_vcpus(KVMState *s) +{ + int max_vcpus = 4; + int ret; + ret = kvm_check_extension(s, KVM_CAP_MAX_VCPUS); + if (ret) { + max_vcpus = ret; + } else { + ret = kvm_check_extension(s, KVM_CAP_NR_VCPUS); + if (ret) { + max_vcpus = ret; + } + } + + return max_vcpus; +} + int kvm_init(void) { static const char upgrade_note[] = @@ -1216,6 +1233,7 @@ int kvm_init(void) const KVMCapabilityInfo *missing_cap; int ret; int i; + int max_vcpus; s = g_malloc0(sizeof(KVMState)); @@ -1256,6 +1274,13 @@ int kvm_init(void) goto err; } + max_vcpus = kvm_max_vcpus(s); + if (smp_cpus > max_vcpus) { + fprintf(stderr, "Number of SMP cpus requested (%d) exceeds max cpus " + "supported by KVM (%d)\n", smp_cpus, max_vcpus); + exit(1); + } + s->vmfd = kvm_ioctl(s, KVM_CREATE_VM, 0); if (s->vmfd < 0) { #ifdef TARGET_S390X