From: Thomas Huth <thuth@xxxxxxxxxx> commit a86cb413f4bf273a9d341a3ab2c2ca44e12eb317 upstream. 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. Reviewed-by: Andrew Jones <drjones@xxxxxxxxxx> Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx> Reviewed-by: David Hildenbrand <david@xxxxxxxxxx> Signed-off-by: Thomas Huth <thuth@xxxxxxxxxx> Message-Id: <20190523164309.13345-9-thuth@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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(-) --- a/arch/mips/kvm/mips.c +++ b/arch/mips/kvm/mips.c @@ -1078,6 +1078,9 @@ int kvm_vm_ioctl_check_extension(struct 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; --- a/arch/powerpc/kvm/powerpc.c +++ b/arch/powerpc/kvm/powerpc.c @@ -629,6 +629,9 @@ int kvm_vm_ioctl_check_extension(struct 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; --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -428,6 +428,7 @@ int kvm_vm_ioctl_check_extension(struct 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; --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2825,6 +2825,9 @@ int kvm_vm_ioctl_check_extension(struct 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_NR_MEMSLOTS: r = KVM_USER_MEM_SLOTS; break; --- a/virt/kvm/arm/arm.c +++ b/virt/kvm/arm/arm.c @@ -217,6 +217,9 @@ int kvm_vm_ioctl_check_extension(struct 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_NR_MEMSLOTS: r = KVM_USER_MEM_SLOTS; break; --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2964,8 +2964,6 @@ static long kvm_vm_ioctl_check_extension 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; }
