[PATCH 4.7 063/184] KVM: s390: dont use current->thread.fpu.* when accessing registers

[Greg Kroah-Hartman]

4.7-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Hildenbrand <d...@linux.vnet.ibm.com>

commit a7d4b8f2565ad0dfdff9a222d1d87990c73b36e8 upstream.

As the meaning of these variables and pointers seems to change more
frequently, let's directly access our save area, instead of going via
current->thread.

Right now, this is broken for set/get_fpu. They simply overwrite the
host registers, as the pointers to the current save area were turned
into the static host save area.

Fixes: 3f6813b9a5e0 ("s390/fpu: allocate 'struct fpu' with the task_struct")
Reported-by: Hao QingFeng <ha...@linux.vnet.ibm.com>
Signed-off-by: David Hildenbrand <d...@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntrae...@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 arch/s390/kvm/kvm-s390.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -1951,9 +1951,10 @@ int kvm_arch_vcpu_ioctl_set_fpu(struct k
                return -EINVAL;
        current->thread.fpu.fpc = fpu->fpc;
        if (MACHINE_HAS_VX)
-               convert_fp_to_vx(current->thread.fpu.vxrs, (freg_t *)fpu->fprs);
+               convert_fp_to_vx((__vector128 *) vcpu->run->s.regs.vrs,
+                                (freg_t *) fpu->fprs);
        else
-               memcpy(current->thread.fpu.fprs, &fpu->fprs, sizeof(fpu->fprs));
+               memcpy(vcpu->run->s.regs.fprs, &fpu->fprs, sizeof(fpu->fprs));
        return 0;
 }
 
@@ -1962,9 +1963,10 @@ int kvm_arch_vcpu_ioctl_get_fpu(struct k
        /* make sure we have the latest values */
        save_fpu_regs();
        if (MACHINE_HAS_VX)
-               convert_vx_to_fp((freg_t *)fpu->fprs, current->thread.fpu.vxrs);
+               convert_vx_to_fp((freg_t *) fpu->fprs,
+                                (__vector128 *) vcpu->run->s.regs.vrs);
        else
-               memcpy(fpu->fprs, current->thread.fpu.fprs, sizeof(fpu->fprs));
+               memcpy(fpu->fprs, vcpu->run->s.regs.fprs, sizeof(fpu->fprs));
        fpu->fpc = current->thread.fpu.fpc;
        return 0;
 }