On Thu, 23 May 2019 18:43:08 +0200 Thomas Huth thuth@redhat.com wrote:
In the subject: s/unusabled/unusable/
KVM_CAP_MAX_VCPU_ID is currently always reporting KVM_MAX_VCPU_ID on all architectures. However, on s390x, the amount of usable CPUs is determined during runtime - it is depending on the features of the machine the code is running on. Since we are using the vcpu_id as an index into the SCA structures that are defined by the hardware (see e.g. the sca_add_vcpu() function), it is not only the amount of CPUs that is limited by the hard- ware, but also the range of IDs that we can use. Thus KVM_CAP_MAX_VCPU_ID must be determined during runtime on s390x, too. So the handling of KVM_CAP_MAX_VCPU_ID has to be moved from the common code into the architecture specific code, and on s390x we have to return the same value here as for KVM_CAP_MAX_VCPUS. This problem has been discovered with the kvm_create_max_vcpus selftest. With this change applied, the selftest now passes on s390x, too.
Signed-off-by: Thomas Huth thuth@redhat.com
arch/mips/kvm/mips.c | 3 +++ arch/powerpc/kvm/powerpc.c | 3 +++ arch/s390/kvm/kvm-s390.c | 1 + arch/x86/kvm/x86.c | 3 +++ virt/kvm/arm/arm.c | 3 +++ virt/kvm/kvm_main.c | 2 -- 6 files changed, 13 insertions(+), 2 deletions(-)
Reviewed-by: Cornelia Huck cohuck@redhat.com