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| author | Greg Kurz <gkurz@linux.vnet.ibm.com> | 2016-05-09 18:13:37 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2016-05-11 22:37:54 +0200 |
| commit | 0b1b1dfd52a67f4f09a18cb82337199bc90ad7fb (patch) | |
| tree | 7d4ec00b96a96ef12fe3aeab042de758451e1bd4 /virt | |
| parent | KVM: remove NULL return path for vcpu ids >= KVM_MAX_VCPUS (diff) | |
| download | linux-0b1b1dfd52a67f4f09a18cb82337199bc90ad7fb.tar.xz linux-0b1b1dfd52a67f4f09a18cb82337199bc90ad7fb.zip | |
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.c | 4 |
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; } |