queue-4.19/kvm-s390-do-not-report-unusabled-ids-via-kvm_cap_max_vcpu_id.patch

   1 From a86cb413f4bf273a9d341a3ab2c2ca44e12eb317 Mon Sep 17 00:00:00 2001
   2 From: Thomas Huth <thuth@redhat.com>
   3 Date: Thu, 23 May 2019 18:43:08 +0200
   4 Subject: KVM: s390: Do not report unusabled IDs via KVM_CAP_MAX_VCPU_ID
   5
   6 From: Thomas Huth <thuth@redhat.com>
   7
   8 commit a86cb413f4bf273a9d341a3ab2c2ca44e12eb317 upstream.
   9
  10 KVM_CAP_MAX_VCPU_ID is currently always reporting KVM_MAX_VCPU_ID on all
  11 architectures. However, on s390x, the amount of usable CPUs is determined
  12 during runtime - it is depending on the features of the machine the code
  13 is running on. Since we are using the vcpu_id as an index into the SCA
  14 structures that are defined by the hardware (see e.g. the sca_add_vcpu()
  15 function), it is not only the amount of CPUs that is limited by the hard-
  16 ware, but also the range of IDs that we can use.
  17 Thus KVM_CAP_MAX_VCPU_ID must be determined during runtime on s390x, too.
  18 So the handling of KVM_CAP_MAX_VCPU_ID has to be moved from the common
  19 code into the architecture specific code, and on s390x we have to return
  20 the same value here as for KVM_CAP_MAX_VCPUS.
  21 This problem has been discovered with the kvm_create_max_vcpus selftest.
  22 With this change applied, the selftest now passes on s390x, too.
  23
  24 Reviewed-by: Andrew Jones <drjones@redhat.com>
  25 Reviewed-by: Cornelia Huck <cohuck@redhat.com>
  26 Reviewed-by: David Hildenbrand <david@redhat.com>
  27 Signed-off-by: Thomas Huth <thuth@redhat.com>
  28 Message-Id: <20190523164309.13345-9-thuth@redhat.com>
  29 Cc: stable@vger.kernel.org
  30 Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
  31 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  32
  33
  34 ---
  35  arch/mips/kvm/mips.c       |    3 +++
  36  arch/powerpc/kvm/powerpc.c |    3 +++
  37  arch/s390/kvm/kvm-s390.c   |    1 +
  38  arch/x86/kvm/x86.c         |    3 +++
  39  virt/kvm/arm/arm.c         |    3 +++
  40  virt/kvm/kvm_main.c        |    2 --
  41  6 files changed, 13 insertions(+), 2 deletions(-)
  42
  43 --- a/arch/mips/kvm/mips.c
  44 +++ b/arch/mips/kvm/mips.c
  45 @@ -1099,6 +1099,9 @@ int kvm_vm_ioctl_check_extension(struct
  46         case KVM_CAP_MAX_VCPUS:
  47                 r = KVM_MAX_VCPUS;
  48                 break;
  49 +       case KVM_CAP_MAX_VCPU_ID:
  50 +               r = KVM_MAX_VCPU_ID;
  51 +               break;
  52         case KVM_CAP_MIPS_FPU:
  53                 /* We don't handle systems with inconsistent cpu_has_fpu */
  54                 r = !!raw_cpu_has_fpu;
  55 --- a/arch/powerpc/kvm/powerpc.c
  56 +++ b/arch/powerpc/kvm/powerpc.c
  57 @@ -632,6 +632,9 @@ int kvm_vm_ioctl_check_extension(struct
  58         case KVM_CAP_MAX_VCPUS:
  59                 r = KVM_MAX_VCPUS;
  60                 break;
  61 +       case KVM_CAP_MAX_VCPU_ID:
  62 +               r = KVM_MAX_VCPU_ID;
  63 +               break;
  64  #ifdef CONFIG_PPC_BOOK3S_64
  65         case KVM_CAP_PPC_GET_SMMU_INFO:
  66                 r = 1;
  67 --- a/arch/s390/kvm/kvm-s390.c
  68 +++ b/arch/s390/kvm/kvm-s390.c
  69 @@ -489,6 +489,7 @@ int kvm_vm_ioctl_check_extension(struct
  70                 break;
  71         case KVM_CAP_NR_VCPUS:
  72         case KVM_CAP_MAX_VCPUS:
  73 +       case KVM_CAP_MAX_VCPU_ID:
  74                 r = KVM_S390_BSCA_CPU_SLOTS;
  75                 if (!kvm_s390_use_sca_entries())
  76                         r = KVM_MAX_VCPUS;
  77 --- a/arch/x86/kvm/x86.c
  78 +++ b/arch/x86/kvm/x86.c
  79 @@ -2987,6 +2987,9 @@ int kvm_vm_ioctl_check_extension(struct
  80         case KVM_CAP_MAX_VCPUS:
  81                 r = KVM_MAX_VCPUS;
  82                 break;
  83 +       case KVM_CAP_MAX_VCPU_ID:
  84 +               r = KVM_MAX_VCPU_ID;
  85 +               break;
  86         case KVM_CAP_NR_MEMSLOTS:
  87                 r = KVM_USER_MEM_SLOTS;
  88                 break;
  89 --- a/virt/kvm/arm/arm.c
  90 +++ b/virt/kvm/arm/arm.c
  91 @@ -223,6 +223,9 @@ int kvm_vm_ioctl_check_extension(struct
  92         case KVM_CAP_MAX_VCPUS:
  93                 r = KVM_MAX_VCPUS;
  94                 break;
  95 +       case KVM_CAP_MAX_VCPU_ID:
  96 +               r = KVM_MAX_VCPU_ID;
  97 +               break;
  98         case KVM_CAP_NR_MEMSLOTS:
  99                 r = KVM_USER_MEM_SLOTS;
 100                 break;
 101 --- a/virt/kvm/kvm_main.c
 102 +++ b/virt/kvm/kvm_main.c
 103 @@ -2965,8 +2965,6 @@ static long kvm_vm_ioctl_check_extension
 104         case KVM_CAP_MULTI_ADDRESS_SPACE:
 105                 return KVM_ADDRESS_SPACE_NUM;
 106  #endif
 107 -       case KVM_CAP_MAX_VCPU_ID:
 108 -               return KVM_MAX_VCPU_ID;
 109         default:
 110                 break;
 111         }