Hi,
When I tested xm mem-set command and xm mem-max command, I found a bug
in xencomm. About error message, please refer an attached file:
xm-memset20061111.log. My operations are as follows.
1. Boot Xen/dom0. (dom0_mem is default.)
2. xm mem-set Domain-0 400
3. xm mem-max Domain-0 400
4. xm mem-set Domain-0 512
When balloon driver called the memory_op hypercall, xencomm overwrite
in the hypercall parameter. It is extent_start of xen_memory_reservation_t
that is overwritten. However, xencomm does not restore the hypercall
parameter that overwrote. As a result, hypercall of the 200th line in
balloon driver fails.
linux-2.6-xen-sparse/drivers/xen/balloon/balloon.c
167 static int increase_reservation(unsigned long nr_pages)
168 {
169 unsigned long pfn, i, flags;
170 struct page *page;
[snip]
190 set_xen_guest_handle(reservation.extent_start, frame_list);
191 reservation.nr_extents = nr_pages;
192 rc = HYPERVISOR_memory_op(
193 XENMEM_populate_physmap, &reservation);
194 if (rc < nr_pages) {
195 if (rc > 0) {
196 int ret;
197
198 /* We hit the Xen hard limit: reprobe. */
199 reservation.nr_extents = rc;
200 ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation,
201 &reservation);
202 BUG_ON(ret != rc);
203 }
[snip]
This patch saves and restores the hypercall parameter within xencomm.
Signed-off-by: Masaki Kanno <kanno.masaki@xxxxxxxxxxxxxx>
Best regards,
Kan
xm-memset20061111.log
Description: Binary data
xcom_memory_op.patch
Description: Binary data
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