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 <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>
diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index 6d0517a..0369f26 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -1122,6 +1122,9 @@
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;
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 3393b16..aa3a678 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -657,6 +657,9 @@
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;
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index e5e8eb2..28ebd64 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -539,6 +539,7 @@
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;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index acb179f..83aefd7 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3122,6 +3122,9 @@
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;
diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index 90cedeb..7eeebe5 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -224,6 +224,9 @@
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 301089a..ca54b09 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3151,8 +3151,6 @@
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:
