KVM: s390: Fix possible host kernel bug on lctl(g) handling

The lctl(g) instructions require a specific alignment for the parameters.
The architecture requires a specification program check if these alignments
are not used. Enforcing this alignment also removes a possible host BUG,
since the get_guest functions check for proper alignment and emits a BUG.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
index f94da68a5c2220325b47bf2226c61dcdf56fb4ac..61236102203e8746933ae96dab4876b421d901d6 100644 (file)
--- a/arch/s390/kvm/intercept.c
+++ b/arch/s390/kvm/intercept.c
@@ -38,6 +38,9 @@ static int handle_lctlg(struct kvm_vcpu *vcpu)
        if (base2)
                useraddr += vcpu->arch.guest_gprs[base2];
 
+       if (useraddr & 7)
+               return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
+
        reg = reg1;
 
        VCPU_EVENT(vcpu, 5, "lctlg r1:%x, r3:%x,b2:%x,d2:%x", reg1, reg3, base2,
@@ -74,6 +77,9 @@ static int handle_lctl(struct kvm_vcpu *vcpu)
        if (base2)
                useraddr += vcpu->arch.guest_gprs[base2];
 
+       if (useraddr & 3)
+               return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
+
        VCPU_EVENT(vcpu, 5, "lctl r1:%x, r3:%x,b2:%x,d2:%x", reg1, reg3, base2,
                   disp2);