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Commit a86cb413 authored by Thomas Huth's avatar Thomas Huth Committed by Christian Borntraeger
Browse files

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: default avatarAndrew Jones <drjones@redhat.com>
Reviewed-by: default avatarCornelia Huck <cohuck@redhat.com>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Signed-off-by: default avatarThomas Huth <thuth@redhat.com>
Message-Id: <20190523164309.13345-9-thuth@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
parent eb1f2f38

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;