diff options
| author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2013-10-15 16:08:34 +0200 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2013-10-24 17:17:11 +0200 |
| commit | 4725c86055f5bbdcdfe47199c0715881893a2c79 (patch) | |
| tree | e201bd8d8a11e58117e9ecf360f3fab43c6267e9 /arch/s390/kvm | |
| parent | 01a7cfa24afd8e18ce691d3c2f1e1f093cf3a900 (diff) | |
s390: fix save and restore of the floating-point-control register
The FPC_VALID_MASK has been used to check the validity of the value
to be loaded into the floating-point-control register. With the
introduction of the floating-point extension facility and the
decimal-floating-point additional bits have been defined which need
to be checked in a non straight forward way. So far these bits have
been ignored which can cause an incorrect results for decimal-
floating-point operations, e.g. an incorrect rounding mode to be
set after signal return.
The static check with the FPC_VALID_MASK is replaced with a trial
load of the floating-point-control value, see test_fp_ctl.
In addition an information leak with the padding word between the
floating-point-control word and the floating-point registers in
the s390_fp_regs is fixed.
Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/kvm')
| -rw-r--r-- | arch/s390/kvm/kvm-s390.c | 23 |
1 files changed, 15 insertions, 8 deletions
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 776dafe918db..ed8064cb5c49 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -343,10 +343,11 @@ void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) { - save_fp_regs(&vcpu->arch.host_fpregs); + save_fp_ctl(&vcpu->arch.host_fpregs.fpc); + save_fp_regs(vcpu->arch.host_fpregs.fprs); save_access_regs(vcpu->arch.host_acrs); - vcpu->arch.guest_fpregs.fpc &= FPC_VALID_MASK; - restore_fp_regs(&vcpu->arch.guest_fpregs); + restore_fp_ctl(&vcpu->arch.guest_fpregs.fpc); + restore_fp_regs(vcpu->arch.guest_fpregs.fprs); restore_access_regs(vcpu->run->s.regs.acrs); gmap_enable(vcpu->arch.gmap); atomic_set_mask(CPUSTAT_RUNNING, &vcpu->arch.sie_block->cpuflags); @@ -356,9 +357,11 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) { atomic_clear_mask(CPUSTAT_RUNNING, &vcpu->arch.sie_block->cpuflags); gmap_disable(vcpu->arch.gmap); - save_fp_regs(&vcpu->arch.guest_fpregs); + save_fp_ctl(&vcpu->arch.guest_fpregs.fpc); + save_fp_regs(vcpu->arch.guest_fpregs.fprs); save_access_regs(vcpu->run->s.regs.acrs); - restore_fp_regs(&vcpu->arch.host_fpregs); + restore_fp_ctl(&vcpu->arch.host_fpregs.fpc); + restore_fp_regs(vcpu->arch.host_fpregs.fprs); restore_access_regs(vcpu->arch.host_acrs); } @@ -618,9 +621,12 @@ int kvm_arch_vcpu_ioctl_get_sregs(struct kvm_vcpu *vcpu, int kvm_arch_vcpu_ioctl_set_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu) { + if (test_fp_ctl(fpu->fpc)) + return -EINVAL; memcpy(&vcpu->arch.guest_fpregs.fprs, &fpu->fprs, sizeof(fpu->fprs)); - vcpu->arch.guest_fpregs.fpc = fpu->fpc & FPC_VALID_MASK; - restore_fp_regs(&vcpu->arch.guest_fpregs); + vcpu->arch.guest_fpregs.fpc = fpu->fpc; + restore_fp_ctl(&vcpu->arch.guest_fpregs.fpc); + restore_fp_regs(vcpu->arch.guest_fpregs.fprs); return 0; } @@ -876,7 +882,8 @@ int kvm_s390_vcpu_store_status(struct kvm_vcpu *vcpu, unsigned long addr) * copying in vcpu load/put. Lets update our copies before we save * it into the save area */ - save_fp_regs(&vcpu->arch.guest_fpregs); + save_fp_ctl(&vcpu->arch.guest_fpregs.fpc); + save_fp_regs(vcpu->arch.guest_fpregs.fprs); save_access_regs(vcpu->run->s.regs.acrs); if (__guestcopy(vcpu, addr + offsetof(struct save_area, fp_regs), |