From a86cb413f4bf273a9d341a3ab2c2ca44e12eb317 Mon Sep 17 00:00:00 2001 From: Thomas Huth Date: Thu, 23 May 2019 18:43:08 +0200 Subject: KVM: s390: Do not report unusabled IDs via KVM_CAP_MAX_VCPU_ID 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 Reviewed-by: Cornelia Huck Reviewed-by: David Hildenbrand Signed-off-by: Thomas Huth Message-Id: <20190523164309.13345-9-thuth@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Christian Borntraeger --- virt/kvm/arm/arm.c | 3 +++ virt/kvm/kvm_main.c | 2 -- 2 files changed, 3 insertions(+), 2 deletions(-) (limited to 'virt') 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 301089a462c4..ca54b09adf5b 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -3151,8 +3151,6 @@ 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: -- cgit