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Subject[PATCH] hv_balloon: Add the support of hibernation
Date
When hibernation is enabled, we must ignore the balloon up/down and
hot-add requests from the host, if any.

Fow now, if people want to test hibernation, please blacklist hv_balloon
or do not enable Dynamic Memory and Memory Resizing. See the comment in
balloon_probe() for more info.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
---

This patch is basically a pure Hyper-V specific change and it has a
build dependency on the commit 271b2224d42f ("Drivers: hv: vmbus: Implement
suspend/resume for VSC drivers for hibernation"), which is on Sasha Levin's
Hyper-V tree's hyperv-next branch:
https://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux.git/log/?h=hyperv-next

I request this patch should go through Sasha's tree rather than the
other tree(s).

drivers/hv/hv_balloon.c | 101 +++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 99 insertions(+), 2 deletions(-)

diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index 34bd735..7df0f67 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -24,6 +24,8 @@

#include <linux/hyperv.h>

+#include <asm/mshyperv.h>
+
#define CREATE_TRACE_POINTS
#include "hv_trace_balloon.h"

@@ -457,6 +459,7 @@ struct hot_add_wrk {
struct work_struct wrk;
};

+static bool allow_hibernation;
static bool hot_add = true;
static bool do_hot_add;
/*
@@ -1053,8 +1056,12 @@ static void hot_add_req(struct work_struct *dummy)
else
resp.result = 0;

- if (!do_hot_add || (resp.page_count == 0))
- pr_err("Memory hot add failed\n");
+ if (!do_hot_add || resp.page_count == 0) {
+ if (!allow_hibernation)
+ pr_err("Memory hot add failed\n");
+ else
+ pr_info("Ignore hot-add request!\n");
+ }

dm->state = DM_INITIALIZED;
resp.hdr.trans_id = atomic_inc_return(&trans_id);
@@ -1509,6 +1516,11 @@ static void balloon_onchannelcallback(void *context)
break;

case DM_BALLOON_REQUEST:
+ if (allow_hibernation) {
+ pr_info("Ignore balloon-up request!\n");
+ break;
+ }
+
if (dm->state == DM_BALLOON_UP)
pr_warn("Currently ballooning\n");
bal_msg = (struct dm_balloon *)recv_buffer;
@@ -1518,6 +1530,11 @@ static void balloon_onchannelcallback(void *context)
break;

case DM_UNBALLOON_REQUEST:
+ if (allow_hibernation) {
+ pr_info("Ignore balloon-down request!\n");
+ break;
+ }
+
dm->state = DM_BALLOON_DOWN;
balloon_down(dm,
(struct dm_unballoon_request *)recv_buffer);
@@ -1623,6 +1640,11 @@ static int balloon_connect_vsp(struct hv_device *dev)
cap_msg.hdr.size = sizeof(struct dm_capabilities);
cap_msg.hdr.trans_id = atomic_inc_return(&trans_id);

+ /*
+ * When hibernation (i.e. virtual ACPI S4 state) is enabled, the host
+ * currently still requires the bits to be set, so we have to add code
+ * to fail the host's hot-add and balloon up/down requests, if any.
+ */
cap_msg.caps.cap_bits.balloon = 1;
cap_msg.caps.cap_bits.hot_add = 1;

@@ -1672,6 +1694,24 @@ static int balloon_probe(struct hv_device *dev,
{
int ret;

+#if 0
+ /*
+ * The patch to implement hv_is_hibernation_supported() is going
+ * through the tip tree. For now, let's hardcode allow_hibernation
+ * to false to keep the current behavior of hv_balloon. If people
+ * want to test hibernation, please blacklist hv_balloon fow now
+ * or do not enable Dynamid Memory and Memory Resizing.
+ *
+ * We'll remove the conditional compilation as soon as
+ * hv_is_hibernation_supported() is available in the mainline tree.
+ */
+ allow_hibernation = hv_is_hibernation_supported();
+#else
+ allow_hibernation = false;
+#endif
+ if (allow_hibernation)
+ hot_add = false;
+
#ifdef CONFIG_MEMORY_HOTPLUG
do_hot_add = hot_add;
#else
@@ -1711,6 +1751,8 @@ static int balloon_probe(struct hv_device *dev,
return 0;

probe_error:
+ dm_device.state = DM_INIT_ERROR;
+ dm_device.thread = NULL;
vmbus_close(dev->channel);
#ifdef CONFIG_MEMORY_HOTPLUG
unregister_memory_notifier(&hv_memory_nb);
@@ -1752,6 +1794,59 @@ static int balloon_remove(struct hv_device *dev)
return 0;
}

+static int balloon_suspend(struct hv_device *hv_dev)
+{
+ struct hv_dynmem_device *dm = hv_get_drvdata(hv_dev);
+
+ tasklet_disable(&hv_dev->channel->callback_event);
+
+ cancel_work_sync(&dm->balloon_wrk.wrk);
+ cancel_work_sync(&dm->ha_wrk.wrk);
+
+ if (dm->thread) {
+ kthread_stop(dm->thread);
+ dm->thread = NULL;
+ vmbus_close(hv_dev->channel);
+ }
+
+ tasklet_enable(&hv_dev->channel->callback_event);
+
+ return 0;
+
+}
+
+static int balloon_resume(struct hv_device *dev)
+{
+ int ret;
+
+ dm_device.state = DM_INITIALIZING;
+
+ ret = balloon_connect_vsp(dev);
+
+ if (ret != 0)
+ goto out;
+
+ dm_device.thread =
+ kthread_run(dm_thread_func, &dm_device, "hv_balloon");
+ if (IS_ERR(dm_device.thread)) {
+ ret = PTR_ERR(dm_device.thread);
+ dm_device.thread = NULL;
+ goto close_channel;
+ }
+
+ dm_device.state = DM_INITIALIZED;
+ return 0;
+close_channel:
+ vmbus_close(dev->channel);
+out:
+ dm_device.state = DM_INIT_ERROR;
+#ifdef CONFIG_MEMORY_HOTPLUG
+ unregister_memory_notifier(&hv_memory_nb);
+ restore_online_page_callback(&hv_online_page);
+#endif
+ return ret;
+}
+
static const struct hv_vmbus_device_id id_table[] = {
/* Dynamic Memory Class ID */
/* 525074DC-8985-46e2-8057-A307DC18A502 */
@@ -1766,6 +1861,8 @@ static int balloon_remove(struct hv_device *dev)
.id_table = id_table,
.probe = balloon_probe,
.remove = balloon_remove,
+ .suspend = balloon_suspend,
+ .resume = balloon_resume,
.driver = {
.probe_type = PROBE_PREFER_ASYNCHRONOUS,
},
--
1.8.3.1
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