KVM: ia64: fix zero extending for mmio ld1/2/4 emulation in KVM

Only copy in the data actually requested by the instruction emulation
and zero pad the destination register first. This avoids the problem
where emulated mmio access got garbled data from ld2.acq instructions
in the vga console driver.

Signed-off-by: Jes Sorensen <jes@sgi.com>
Acked-by: Xiantao Zhang <xiantao.zhang@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/arch/ia64/kvm/mmio.c b/arch/ia64/kvm/mmio.c
index 351bf70da463..7f1a858bc69f 100644
--- a/arch/ia64/kvm/mmio.c
+++ b/arch/ia64/kvm/mmio.c
@@ -159,7 +159,8 @@ static void mmio_access(struct kvm_vcpu *vcpu, u64 src_pa, u64 *dest,
 
         if (p->u.ioreq.state == STATE_IORESP_READY) {
                 if (dir == IOREQ_READ)
-                        *dest = p->u.ioreq.data;
+                        /* it's necessary to ensure zero extending */
+                        *dest = p->u.ioreq.data & (~0UL >> (64-(s*8)));
         } else
                 panic_vm(vcpu);
 out: