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authorGreg Kurz <gkurz@linux.vnet.ibm.com>2016-05-09 18:13:37 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2016-05-11 22:37:54 +0200
commit0b1b1dfd52a67f4f09a18cb82337199bc90ad7fb (patch)
tree7d4ec00b96a96ef12fe3aeab042de758451e1bd4 /virt
parent9b9e3fc4d5a31f6050508f2404369beac4356867 (diff)
downloadlinux-stericsson-0b1b1dfd52a67f4f09a18cb82337199bc90ad7fb.tar.gz
kvm: introduce KVM_MAX_VCPU_ID
The KVM_MAX_VCPUS define provides the maximum number of vCPUs per guest, and also the upper limit for vCPU ids. This is okay for all archs except PowerPC which can have higher ids, depending on the cpu/core/thread topology. In the worst case (single threaded guest, host with 8 threads per core), it limits the maximum number of vCPUS to KVM_MAX_VCPUS / 8. This patch separates the vCPU numbering from the total number of vCPUs, with the introduction of KVM_MAX_VCPU_ID, as the maximal valid value for vCPU ids plus one. The corresponding KVM_CAP_MAX_VCPU_ID allows userspace to validate vCPU ids before passing them to KVM_CREATE_VCPU. This patch only implements KVM_MAX_VCPU_ID with a specific value for PowerPC. Other archs continue to return KVM_MAX_VCPUS instead. Suggested-by: Radim Krcmar <rkrcmar@redhat.com> Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/kvm_main.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 4fd482fb9260..ed3d9bb18a56 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2272,7 +2272,7 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
int r;
struct kvm_vcpu *vcpu;
- if (id >= KVM_MAX_VCPUS)
+ if (id >= KVM_MAX_VCPU_ID)
return -EINVAL;
vcpu = kvm_arch_vcpu_create(kvm, id);
@@ -2746,6 +2746,8 @@ static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg)
case KVM_CAP_MULTI_ADDRESS_SPACE:
return KVM_ADDRESS_SPACE_NUM;
#endif
+ case KVM_CAP_MAX_VCPU_ID:
+ return KVM_MAX_VCPU_ID;
default:
break;
}