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Date: Thu, 12 Sep 2019 12:08:42 +0200
From: David Hildenbrand <david@...hat.com>
To: Dexuan Cui <decui@...rosoft.com>,
KY Srinivasan <kys@...rosoft.com>,
Haiyang Zhang <haiyangz@...rosoft.com>,
Stephen Hemminger <sthemmin@...rosoft.com>,
"sashal@...nel.org" <sashal@...nel.org>,
"linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Michael Kelley <mikelley@...rosoft.com>
Subject: Re: [PATCH] hv_balloon: Add the support of hibernation
On 12.09.19 01:36, Dexuan Cui wrote:
> 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.
>
Why do you even care about supporting hibernation? Can't you just pause
the VM in the hypervisor and continue to live a happy life? :)
> Signed-off-by: Dexuan Cui <decui@...rosoft.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
I am not sure if that's a good idea. Can't you base this series on
hv_is_hibernation_supported() ?
> + /*
> + * 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,
> },
>
--
Thanks,
David / dhildenb
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