[PATCH] kvm-s390: Fix possible host kernel bug on lctl(g) handling

Christian Borntraeger
2008-07-25T13:55:08Z

From: Christian Borntraeger <borntraeger@de.ibm.com>

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>
---
arch/s390/kvm/intercept.c | 6 ++++++
1 file changed, 6 insertions(+)

Index: kvm/arch/s390/kvm/intercept.c
===================================================================
--- kvm.orig/arch/s390/kvm/intercept.c
+++ kvm/arch/s390/kvm/intercept.c
@@ -38,6 +38,9 @@ static int handle_lctlg(struct kvm_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 *
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);