On 18.02.20 09:40, David Hildenbrand wrote:
> On 14.02.20 23:26, Christian Borntraeger wrote:
>> From: Janosch Frank <frankja@xxxxxxxxxxxxx>
>
> "KVM: s390: protvirt: disallow KVM_GET_ONE_REG/KVM_SET_ONE_REG"
>
>>
>> A lot of the registers are controlled by the Ultravisor and never
>> visible to KVM. Some fields in the sie control block are overlayed, like
>> gbea. As no known userspace uses the ONE_REG interface on s390 if sync
>> regs are available, no functionality is lost if it is disabled for
>> protected guests.
>>
>> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
>> Reviewed-by: Thomas Huth <thuth@xxxxxxxxxx>
>> Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>
>> [borntraeger@xxxxxxxxxx: patch merging, splitting, fixing]
>> Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
>> ---
>> Documentation/virt/kvm/api.rst | 6 ++++--
>> arch/s390/kvm/kvm-s390.c | 3 +++
>> 2 files changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
>> index cb58714fe60d..a82166e5f7d9 100644
>> --- a/Documentation/virt/kvm/api.rst
>> +++ b/Documentation/virt/kvm/api.rst
>> @@ -2117,7 +2117,8 @@ Errors:
>>
>> ====== ============================================================
>> ENOENT no such register
>> - EINVAL invalid register ID, or no such register
>> + EINVAL invalid register ID, or no such register, ONE_REG forbidden
>> + for protected guests (s390)
>
> "invalid register ID, no such register, or used with VMs in protected
> virtualization mode on s390" ?
ack.
>
>> EPERM (arm64) register access not allowed before vcpu finalization
>> ====== ============================================================
>>
>> @@ -2552,7 +2553,8 @@ Errors include:
>>
>> ======== ============================================================
>> ENOENT no such register
>> - EINVAL invalid register ID, or no such register
>> + EINVAL invalid register ID, or no such register, ONE_REG forbidden
>> + for protected guests (s390)
>
> dito
ack
>
>> EPERM (arm64) register access not allowed before vcpu finalization
>> ======== ============================================================
>>
>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
>> index 8db82aaf1275..d20a7fa9d480 100644
>> --- a/arch/s390/kvm/kvm-s390.c
>> +++ b/arch/s390/kvm/kvm-s390.c
>> @@ -4638,6 +4638,9 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
>> case KVM_SET_ONE_REG:
>> case KVM_GET_ONE_REG: {
>> struct kvm_one_reg reg;
>> + r = -EINVAL;
>> + if (kvm_s390_pv_is_protected(vcpu->kvm))
>> + break;
>
> I assume races will be dealt with in your next series.
yes. This is running under vcpu_mutex and we will hold that lock when doing
the gear shift.
>
>> r = -EFAULT;
>> if (copy_from_user(®, argp, sizeof(reg)))
>> break;
>>
>
> With the two nits fixed
>
> Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
>
