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KVM: s390: do not clobber registers during guest reset/store status 

commit 55680890ea upstream.

The initial CPU reset clobbers the userspace fpc and the store status
ioctl clobbers the guest acrs + fpr.  As these calls are only done via
ioctl (and not via vcpu_run), no CPU context is loaded, so we can (and
must) act directly on the sync regs, not on the thread context.

Cc: stable@kernel.org
Fixes: e1788bb995 ("KVM: s390: handle floating point registers in the run ioctl not in vcpu_put/load")
Fixes: 31d8b8d41a ("KVM: s390: handle access registers in the run ioctl not in vcpu_put/load")
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Link: https://lore.kernel.org/r/20200131100205.74720-2-frankja@linux.ibm.com
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Christian Borntraeger 2020-01-31 05:02:00 -05:00 committed by Greg Kroah-Hartman
parent b1f9f9b843
commit 6e41b54999
1 changed files with 2 additions and 4 deletions
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6
arch/s390/kvm/kvm-s390.c
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@ -2863,9 +2863,7 @@ static void kvm_s390_vcpu_initial_reset(struct kvm_vcpu *vcpu)
vcpu->arch.sie_block->gcr[14] = CR14_UNUSED_32 |
CR14_UNUSED_33 |
CR14_EXTERNAL_DAMAGE_SUBMASK;
/* make sure the new fpc will be lazily loaded */
save_fpu_regs();
current->thread.fpu.fpc = 0;
vcpu->run->s.regs.fpc = 0;
vcpu->arch.sie_block->gbea = 1;
vcpu->arch.sie_block->pp = 0;
vcpu->arch.sie_block->fpf &= ~FPF_BPBC;
@ -4354,7 +4352,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
switch (ioctl) {
case KVM_S390_STORE_STATUS:
idx = srcu_read_lock(&vcpu->kvm->srcu);
r = kvm_s390_vcpu_store_status(vcpu, arg);
r = kvm_s390_store_status_unloaded(vcpu, arg);
srcu_read_unlock(&vcpu->kvm->srcu, idx);
break;
case KVM_S390_SET_INITIAL_PSW: {