Commit b13cd24c authored by Roger Pau Monne's avatar Roger Pau Monne Committed by Juergen Gross
Browse files

xen/balloon: improve accuracy of initial balloon target for dom0 



The dom0 balloon target set by the toolstack is the value returned by
XENMEM_current_reservation.  Do the same in the kernel balloon driver and
set the current allocation to the value returned by
XENMEM_current_reservation.  On my test system this causes the kernel
balloon driver target to exactly match the value set by the toolstack in
xenstore.

Note this approach can be used by both PV and PVH dom0s, as the toolstack
always uses XENMEM_current_reservation to set the initial target regardless
of the dom0 type.

Signed-off-by: default avatarRoger Pau Monné <roger.pau@citrix.com>
Reviewed-by: default avatarJuergen Gross <jgross@suse.com>
Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
Message-ID: <20260128110510.46425-3-roger.pau@citrix.com>
parent 0949c646

drivers/xen/balloon.c

+17 −10
Original line number Diff line number Diff line
@@ -724,7 +724,8 @@ static int __init balloon_add_regions(void) 
static int __init balloon_init(void)

{

	struct task_struct *task;

	unsigned long current_pages;

	long current_pages = 0;

	domid_t domid = DOMID_SELF;

	int rc;



	if (!xen_domain())
@@ -732,6 +733,10 @@ static int __init balloon_init(void) 


	pr_info("Initialising balloon driver\n");



	if (xen_initial_domain())

		current_pages = HYPERVISOR_memory_op(XENMEM_current_reservation,

		                                     &domid);

	if (current_pages <= 0) {

		if (xen_pv_domain()) {

			if (xen_released_pages >= xen_start_info->nr_pages)

				goto underflow;
@@ -740,7 +745,9 @@ static int __init balloon_init(void) 
		} else {

			if (xen_unpopulated_pages >= get_num_physpages())

				goto underflow;

		current_pages = get_num_physpages() - xen_unpopulated_pages;

			current_pages = get_num_physpages() -

			                xen_unpopulated_pages;

		}

	}



	balloon_stats.current_pages = current_pages;