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KVM: s390: Do not report unusabled IDs via KVM_CAP_MAX_VCPU_ID

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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>
This commit is contained in:
Thomas Huth 2019-05-23 18:43:08 +02:00 committed by Christian Borntraeger
parent eb1f2f387d
commit a86cb413f4
6 changed files with 13 additions and 2 deletions
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3
arch/mips/kvm/mips.c
View File

@ -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;

3
arch/powerpc/kvm/powerpc.c
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@ -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;

1
arch/s390/kvm/kvm-s390.c
View File

@ -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;

3
arch/x86/kvm/x86.c
View File

@ -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;

3
virt/kvm/arm/arm.c
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@ -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;

2
virt/kvm/kvm_main.c
View File

@ -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: