From 5266b8e4445cc836c46689d80a9ff539fa3bfbda Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Thu, 26 Oct 2017 11:50:56 +0200 Subject: [PATCH] xen: fix booting ballooned down hvm guest Commit 96edd61dcf44362d3ef0bed1a5361e0ac7886a63 ("xen/balloon: don't online new memory initially") introduced a regression when booting a HVM domain with memory less than mem-max: instead of ballooning down immediately the system would try to use the memory up to mem-max resulting in Xen crashing the domain. For HVM domains the current size will be reflected in Xenstore node memory/static-max instead of memory/target. Additionally we have to trigger the ballooning process at once. Cc: # 4.13 Fixes: 96edd61dcf44362d3ef0bed1a5361e0ac7886a63 ("xen/balloon: don't online new memory initially") Reported-by: Simon Gaiser Suggested-by: Boris Ostrovsky Signed-off-by: Juergen Gross Reviewed-by: Boris Ostrovsky Signed-off-by: Boris Ostrovsky --- drivers/xen/xen-balloon.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) diff --git a/drivers/xen/xen-balloon.c b/drivers/xen/xen-balloon.c index e89136ab851e..b437fccd4e62 100644 --- a/drivers/xen/xen-balloon.c +++ b/drivers/xen/xen-balloon.c @@ -57,7 +57,7 @@ static int register_balloon(struct device *dev); static void watch_target(struct xenbus_watch *watch, const char *path, const char *token) { - unsigned long long new_target; + unsigned long long new_target, static_max; int err; static bool watch_fired; static long target_diff; @@ -72,13 +72,20 @@ static void watch_target(struct xenbus_watch *watch, * pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10. */ new_target >>= PAGE_SHIFT - 10; - if (watch_fired) { - balloon_set_new_target(new_target - target_diff); - return; + + if (!watch_fired) { + watch_fired = true; + err = xenbus_scanf(XBT_NIL, "memory", "static-max", "%llu", + &static_max); + if (err != 1) + static_max = new_target; + else + static_max >>= PAGE_SHIFT - 10; + target_diff = xen_pv_domain() ? 0 + : static_max - balloon_stats.target_pages; } - watch_fired = true; - target_diff = new_target - balloon_stats.target_pages; + balloon_set_new_target(new_target - target_diff); } static struct xenbus_watch target_watch = { .node = "memory/target",