tools/kdd: don't use a pointer to an unaligned field.

The 'val' field in the packet is byte-aligned (because it is part of a
packed struct), but the pointer argument to kdd_rdmsr() has the normal
alignment constraints for a uint64_t *.  Use a local variable to make sure
the passed pointer has the correct alignment.

Reported-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Tim Deegan <tim@xen.org>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Tested-by: Roger Pau Monné <roger.pau@citrix.com>

tools/debugger/kdd/kdd.c

@@ -710,11 +710,13 @@ static void kdd_handle_read_ctrl(kdd_state *s)
 static void kdd_handle_read_msr(kdd_state *s)
 {
     uint32_t msr = s->rxp.cmd.msr.msr;
+    uint64_t val;
     int ok;
     KDD_LOG(s, "Read MSR 0x%"PRIx32"\n", msr);
 
-    ok = (kdd_rdmsr(s->guest, s->cpuid, msr, &s->txp.cmd.msr.val) == 0);
+    ok = (kdd_rdmsr(s->guest, s->cpuid, msr, &val) == 0);
     s->txp.cmd.msr.msr = msr;
+    s->txp.cmd.msr.val = val;
     s->txp.cmd.msr.status = (ok ? KDD_STATUS_SUCCESS : KDD_STATUS_FAILURE);
     kdd_send_cmd(s, KDD_CMD_READ_MSR, 0);
 }