On Tue, 28 May 2019 13:00:30 +0200 Christian Borntraeger <borntraeger@xxxxxxxxxx> wrote: > Paolo, Radim, > > would you consider this patch (or the full series) as 5.2 material or 5.3 material? FWIW, I'd consider this patch 5.2 material, as we're currently relaying wrong values to userspace. > > > On 23.05.19 18:43, Thomas Huth wrote: > > 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@xxxxxxxxxx> > > --- > > 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(-)
