On Thu, May 23, 2019 at 06:43:08PM +0200, 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(-) > > diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c > index 6d0517ac18e5..0369f26ab96d 100644 > --- a/arch/mips/kvm/mips.c > +++ b/arch/mips/kvm/mips.c > @@ -1122,6 +1122,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) > case KVM_CAP_MAX_VCPUS: > r = KVM_MAX_VCPUS; > break; > + case KVM_CAP_MAX_VCPU_ID: > + r = KVM_MAX_VCPU_ID; > + break; > case KVM_CAP_MIPS_FPU: > /* We don't handle systems with inconsistent cpu_has_fpu */ > r = !!raw_cpu_has_fpu; > diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c > index 3393b166817a..aa3a678711be 100644 > --- a/arch/powerpc/kvm/powerpc.c > +++ b/arch/powerpc/kvm/powerpc.c > @@ -657,6 +657,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) > case KVM_CAP_MAX_VCPUS: > r = KVM_MAX_VCPUS; > break; > + case KVM_CAP_MAX_VCPU_ID: > + r = KVM_MAX_VCPU_ID; > + break; > #ifdef CONFIG_PPC_BOOK3S_64 > case KVM_CAP_PPC_GET_SMMU_INFO: > r = 1; > diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c > index 8d6d75db8de6..871d2e99b156 100644 > --- a/arch/s390/kvm/kvm-s390.c > +++ b/arch/s390/kvm/kvm-s390.c > @@ -539,6 +539,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) > break; > case KVM_CAP_NR_VCPUS: > case KVM_CAP_MAX_VCPUS: > + case KVM_CAP_MAX_VCPU_ID: > r = KVM_S390_BSCA_CPU_SLOTS; > if (!kvm_s390_use_sca_entries()) > r = KVM_MAX_VCPUS; > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 536b78c4af6e..09a07d6a154e 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -3122,6 +3122,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) > case KVM_CAP_MAX_VCPUS: > r = KVM_MAX_VCPUS; > break; > + case KVM_CAP_MAX_VCPU_ID: > + r = KVM_MAX_VCPU_ID; > + break; > case KVM_CAP_PV_MMU: /* obsolete */ > r = 0; > break; > diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c > index 90cedebaeb94..7eeebe5e9da2 100644 > --- a/virt/kvm/arm/arm.c > +++ b/virt/kvm/arm/arm.c > @@ -224,6 +224,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) > case KVM_CAP_MAX_VCPUS: > r = KVM_MAX_VCPUS; > break; > + case KVM_CAP_MAX_VCPU_ID: > + r = KVM_MAX_VCPU_ID; > + break; > case KVM_CAP_MSI_DEVID: > if (!kvm) > r = -EINVAL; > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index f0d13d9d125d..c09259dd6286 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -3146,8 +3146,6 @@ 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; > case KVM_CAP_NR_MEMSLOTS: > return KVM_USER_MEM_SLOTS; > default: > -- > 2.21.0 > Reviewed-by: Andrew Jones <drjones@xxxxxxxxxx>
