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Date: Tue, 7 Jan 2020 21:09:50 +0800
From: lantianyu1986@...il.com
To: kys@...rosoft.com, haiyangz@...rosoft.com, sthemmin@...rosoft.com,
sashal@...nel.org, michael.h.kelley@...rosoft.com, david@...hat.com
Cc: Tianyu Lan <Tianyu.Lan@...rosoft.com>,
linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org,
vkuznets@...hat.com, eric.devolder@...cle.com
Subject: [RFC PATCH V2 10/10] x86/Hyper-V: Workaround Hyper-V unballoon msg bug
From: Tianyu Lan <Tianyu.Lan@...rosoft.com>
Hyper-V sends unballoon msg instead of mem hot add msg in some
case. System doesn't receive balloon msg before unballoon msg
and this will cause balloon_down() to produce warning of
free non-exist memory. Workaround the issue via treating
unballoon msg as mem hot-add msg when mem hot-add is
enabled.
Signed-off-by: Tianyu Lan <Tianyu.Lan@...rosoft.com>
---
drivers/hv/hv_balloon.c | 116 +++++++++++++++++++++++++++---------------------
1 file changed, 66 insertions(+), 50 deletions(-)
diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index 5aaae62955bf..7f3e7ab22d5d 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -486,6 +486,9 @@ union dm_msg_info {
struct {
__u32 num_pages;
} balloon_state;
+ struct {
+ struct dm_unballoon_request *request;
+ } unballoon_state;
struct {
union dm_mem_page_range ha_page_range;
union dm_mem_page_range ha_region_range;
@@ -1155,6 +1158,21 @@ static unsigned long process_hot_add(unsigned long pg_start,
return pfn_cnt;
}
+ if ((rg_start == 0) && (!dm_device.host_specified_ha_region)) {
+ /*
+ * The host has not specified the hot-add region.
+ * Based on the hot-add page range being specified,
+ * compute a hot-add region that can cover the pages
+ * that need to be hot-added while ensuring the alignment
+ * and size requirements of Linux as it relates to hot-add.
+ */
+ rg_size = (pfn_cnt / HA_CHUNK) * HA_CHUNK;
+ if (pfn_cnt % HA_CHUNK)
+ rg_size += HA_CHUNK;
+
+ rg_start = (pg_start / HA_CHUNK) * HA_CHUNK;
+ }
+
if (!dm_device.host_specified_ha_region) {
covered = pfn_covered(pg_start, pfn_cnt);
if (covered < 0)
@@ -1488,28 +1506,6 @@ static void hot_add_req(union dm_msg_info *msg_info)
rg_start = msg_info->hot_add.ha_region_range.finfo.start_page;
rg_sz = msg_info->hot_add.ha_region_range.finfo.page_cnt;
- if ((rg_start == 0) && (!dm->host_specified_ha_region)) {
- unsigned long region_size;
- unsigned long region_start;
-
- /*
- * The host has not specified the hot-add region.
- * Based on the hot-add page range being specified,
- * compute a hot-add region that can cover the pages
- * that need to be hot-added while ensuring the alignment
- * and size requirements of Linux as it relates to hot-add.
- */
- region_start = pg_start;
- region_size = (pfn_cnt / HA_CHUNK) * HA_CHUNK;
- if (pfn_cnt % HA_CHUNK)
- region_size += HA_CHUNK;
-
- region_start = (pg_start / HA_CHUNK) * HA_CHUNK;
-
- rg_start = region_start;
- rg_sz = region_size;
- }
-
if (do_hot_add)
resp.page_count = process_hot_add(pg_start, pfn_cnt,
rg_start, rg_sz);
@@ -1823,41 +1819,37 @@ static void balloon_up(union dm_msg_info *msg_info)
}
-static void dm_msg_work(struct work_struct *dummy)
-{
- union dm_msg_info *msg_info = &dm_device.dm_wrk.dm_msg;
-
- switch (dm_device.dm_wrk.msg_type) {
- case DM_BALLOON_REQUEST:
- balloon_up(msg_info);
- break;
- case DM_MEM_HOT_ADD_REQUEST:
- hot_add_req(msg_info);
- break;
- case DM_MEM_HOT_REMOVE_REQUEST:
- hot_remove_req(msg_info);
- break;
- default:
- return;
- }
-}
-
-static void balloon_down(struct hv_dynmem_device *dm,
- struct dm_unballoon_request *req)
+static void balloon_down(union dm_msg_info *msg_info)
{
+ struct dm_unballoon_request *req = msg_info->unballoon_state.request;
union dm_mem_page_range *range_array = req->range_array;
+ struct hv_dynmem_device *dm = &dm_device;
+ unsigned int prev_pages_ballooned = dm->num_pages_ballooned;
int range_count = req->range_count;
struct dm_unballoon_response resp;
int i;
- unsigned int prev_pages_ballooned = dm->num_pages_ballooned;
for (i = 0; i < range_count; i++) {
- free_balloon_pages(dm, &range_array[i]);
- complete(&dm_device.config_event);
+ /*
+ * Hyper-V has a bug that send unballoon msg instead
+ * of hot add msg even if there is no balloon msg sent
+ * before. Treat all unballoon msgs as hot add msgs
+ * if hot add capability is enabled.
+ */
+ if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG) && do_hot_add) {
+ dm->host_specified_ha_region = false;
+ dm->num_pages_added +=
+ process_hot_add(range_array[i].finfo.start_page,
+ range_array[i].finfo.page_cnt, 0, 0);
+ } else {
+ free_balloon_pages(dm, &range_array[i]);
+ complete(&dm_device.config_event);
+ }
}
- pr_debug("Freed %u ballooned pages.\n",
- prev_pages_ballooned - dm->num_pages_ballooned);
+ if (!do_hot_add)
+ pr_debug("Freed %u ballooned pages.\n",
+ prev_pages_ballooned - dm->num_pages_ballooned);
if (req->more_pages == 1)
return;
@@ -1875,6 +1867,28 @@ static void balloon_down(struct hv_dynmem_device *dm,
dm->state = DM_INITIALIZED;
}
+static void dm_msg_work(struct work_struct *dummy)
+{
+ union dm_msg_info *msg_info = &dm_device.dm_wrk.dm_msg;
+
+ switch (dm_device.dm_wrk.msg_type) {
+ case DM_BALLOON_REQUEST:
+ balloon_up(msg_info);
+ break;
+ case DM_UNBALLOON_REQUEST:
+ balloon_down(msg_info);
+ break;
+ case DM_MEM_HOT_ADD_REQUEST:
+ hot_add_req(msg_info);
+ break;
+ case DM_MEM_HOT_REMOVE_REQUEST:
+ hot_remove_req(msg_info);
+ break;
+ default:
+ return;
+ }
+}
+
static void balloon_onchannelcallback(void *context);
static int dm_thread_func(void *dm_dev)
@@ -2024,8 +2038,10 @@ static void balloon_onchannelcallback(void *context)
}
dm->state = DM_BALLOON_DOWN;
- balloon_down(dm,
- (struct dm_unballoon_request *)recv_buffer);
+ dm_wrk->msg_type = DM_UNBALLOON_REQUEST;
+ msg_info->unballoon_state.request
+ = (struct dm_unballoon_request *)recv_buffer;
+ schedule_work(&dm_wrk->wrk);
break;
case DM_MEM_HOT_ADD_REQUEST:
--
2.14.5
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