There is still a bit of an issue after the last set of changes made by
mlarkin@. The changed get_input_data() interface takes a pointer to a
uint32_t as an argument, but only modifies the bytes that correspond
to the access size. That means that if we read the value into an
uint32_t that is allocated on the stack, because if the access size is
less than 4 bytes, we end up with stack garbage in the variable. This
is a problem in the mc146818 emulation code.
The result is that seabios (sometimes) detects the wrong memory size
and subsequently triggers the following kernel printf:
unknown memory type 1 for GPA 0x207bffd0
Not sure what happens with the VM at that point. It seems to be
hanging.
Diff below fixes the issue. As far as I can see the i8253 and i8259
emulation code isn't affected as the uint32_t stack variable gets
converted into a uint8_t before being used. But perhaps we should
initialize the stack variables there as well to prevent further
accidents.
ok?
Index: mc146818.c
===================================================================
RCS file: /cvs/src/usr.sbin/vmd/mc146818.c,v
retrieving revision 1.10
diff -u -p -r1.10 mc146818.c
--- mc146818.c 25 Mar 2017 22:36:53 -0000 1.10
+++ mc146818.c 26 Mar 2017 14:26:10 -0000
@@ -249,7 +249,7 @@ vcpu_exit_mc146818(struct vm_run_params
union vm_exit *vei = vrp->vrp_exit;
uint16_t port = vei->vei.vei_port;
uint8_t dir = vei->vei.vei_dir;
- uint32_t data;
+ uint32_t data = 0;
get_input_data(vei, &data);
