KVM: s390: Do not report unusabled IDs via KVM_CAP_MAX_VCPU_ID (a86cb413) · Commits · 戴 / test

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@redhat.com> Reviewed-by:

Cornelia Huck <cohuck@redhat.com> Reviewed-by:

David Hildenbrand <david@redhat.com> Signed-off-by:

Thomas Huth <thuth@redhat.com> Message-Id: <20190523164309.13345-9-thuth@redhat.com> Cc: stable@vger.kernel.org Signed-off-by:

Christian Borntraeger <borntraeger@de.ibm.com>

arch/mips/kvm/mips.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -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;

arch/powerpc/kvm/powerpc.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -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;

arch/s390/kvm/kvm-s390.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -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;

arch/x86/kvm/x86.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -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;

virt/kvm/arm/arm.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -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;

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