The routine ar_translation() can be reached by both the instruction intercept path (where the access registers had been loaded with the guest register contents), and the MEM_OP ioctls (which hadn't). This latter case means that any ALET the guest expects to be used would be ignored.
Fix this by swapping the host/guest access registers around the MEM_OP ioctl, in the same way that the KVM_RUN ioctl does with sync_regs()/store_regs(). The full register swap isn't needed here, since only the access registers are used in this interface. Introduce a boolean in the kvm_vcpu_arch struct to indicate the guest ARs have been loaded into the registers. This permits a warning to be emitted if entering this path without a proper register setup. Suggested-by: Christian Borntraeger <[email protected]> Signed-off-by: Eric Farman <[email protected]> --- arch/s390/include/asm/kvm_host.h | 1 + arch/s390/kvm/gaccess.c | 2 ++ arch/s390/kvm/kvm-s390.c | 11 +++++++++++ 3 files changed, 14 insertions(+) diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h index 52664105a473..c86215eb4ca7 100644 --- a/arch/s390/include/asm/kvm_host.h +++ b/arch/s390/include/asm/kvm_host.h @@ -765,6 +765,7 @@ struct kvm_vcpu_arch { __u64 cputm_start; bool gs_enabled; bool skey_enabled; + bool acrs_loaded; struct kvm_s390_pv_vcpu pv; union diag318_info diag318_info; }; diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c index 5bfcc50c1a68..33587bb4c9e8 100644 --- a/arch/s390/kvm/gaccess.c +++ b/arch/s390/kvm/gaccess.c @@ -391,6 +391,8 @@ static int ar_translation(struct kvm_vcpu *vcpu, union asce *asce, u8 ar, if (ar >= NUM_ACRS) return -EINVAL; + WARN_ON_ONCE(!vcpu->arch.acrs_loaded); + save_access_regs(vcpu->run->s.regs.acrs); alet.val = vcpu->run->s.regs.acrs[ar]; diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index ea63ac769889..c60ec561f7f1 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -3951,6 +3951,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu) KVM_SYNC_ARCH0 | KVM_SYNC_PFAULT | KVM_SYNC_DIAG318; + vcpu->arch.acrs_loaded = false; kvm_s390_set_prefix(vcpu, 0); if (test_kvm_facility(vcpu->kvm, 64)) vcpu->run->kvm_valid_regs |= KVM_SYNC_RICCB; @@ -4951,6 +4952,7 @@ static void sync_regs(struct kvm_vcpu *vcpu) } save_access_regs(vcpu->arch.host_acrs); restore_access_regs(vcpu->run->s.regs.acrs); + vcpu->arch.acrs_loaded = true; /* save host (userspace) fprs/vrs */ save_fpu_regs(); vcpu->arch.host_fpregs.fpc = current->thread.fpu.fpc; @@ -5021,6 +5023,7 @@ static void store_regs(struct kvm_vcpu *vcpu) kvm_run->s.regs.pfc = vcpu->arch.pfault_compare; save_access_regs(vcpu->run->s.regs.acrs); restore_access_regs(vcpu->arch.host_acrs); + vcpu->arch.acrs_loaded = false; /* Save guest register state */ save_fpu_regs(); vcpu->run->s.regs.fpc = current->thread.fpu.fpc; @@ -5391,6 +5394,11 @@ static long kvm_s390_vcpu_mem_op(struct kvm_vcpu *vcpu, return -ENOMEM; } + /* Swap host/guest access registers */ + save_access_regs(vcpu->arch.host_acrs); + restore_access_regs(vcpu->run->s.regs.acrs); + vcpu->arch.acrs_loaded = true; + acc_mode = mop->op == KVM_S390_MEMOP_LOGICAL_READ ? GACC_FETCH : GACC_STORE; if (mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY) { r = check_gva_range(vcpu, mop->gaddr, mop->ar, mop->size, @@ -5420,6 +5428,9 @@ static long kvm_s390_vcpu_mem_op(struct kvm_vcpu *vcpu, kvm_s390_inject_prog_irq(vcpu, &vcpu->arch.pgm); out_free: + save_access_regs(vcpu->run->s.regs.acrs); + restore_access_regs(vcpu->arch.host_acrs); + vcpu->arch.acrs_loaded = false; vfree(tmpbuf); return r; } -- 2.40.1
