RE: [PATCH 6/7] Drivers: hv: vmbus: Suspend/resume the vmbus itself for hibernation

Michael Kelley
2019-07-30T23:25:43Z

From: Dexuan Cui <decui@microsoft.com> Sent: Monday, July 8, 2019 10:30 PM
>
> This is needed when we resume the old kernel from the "current" kernel.

Perhaps a bit more descriptive commit message could be supplied?

>
> Signed-off-by: Dexuan Cui <decui@microsoft.com>
> ---
> drivers/hv/connection.c | 3 +--
> drivers/hv/hyperv_vmbus.h | 2 ++
> drivers/hv/vmbus_drv.c | 40 ++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 43 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
> index 09829e1..806319c 100644
> --- a/drivers/hv/connection.c
> +++ b/drivers/hv/connection.c
> @@ -59,8 +59,7 @@ static __u32 vmbus_get_next_version(__u32 current_version)
> }
> }
>
> -static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
> - __u32 version)
> +int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
> {
> int ret = 0;
> unsigned int cur_cpu;
> diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
> index 26ea161..e657197 100644
> --- a/drivers/hv/hyperv_vmbus.h
> +++ b/drivers/hv/hyperv_vmbus.h
> @@ -274,6 +274,8 @@ struct vmbus_msginfo {
>
> extern struct vmbus_connection vmbus_connection;
>
> +int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version);
> +
> static inline void vmbus_send_interrupt(u32 relid)
> {
> sync_set_bit(relid, vmbus_connection.send_int_page);
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index 1c2d935..1730e7b 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -2045,6 +2045,41 @@ static int vmbus_acpi_add(struct acpi_device *device)
> return ret_val;
> }
>
> +static int vmbus_bus_suspend(struct device *dev)
> +{
> + vmbus_initiate_unload(false);
> +
> + vmbus_connection.conn_state = DISCONNECTED;
> +
> + return 0;
> +}
> +
> +static int vmbus_bus_resume(struct device *dev)
> +{
> + struct vmbus_channel_msginfo *msginfo;
> + size_t msgsize;
> + int ret;
> +
> + msgsize = sizeof(*msginfo) +
> + sizeof(struct vmbus_channel_initiate_contact);
> +
> + msginfo = kzalloc(msgsize, GFP_KERNEL);
> +
> + if (msginfo == NULL)
> + return -ENOMEM;
> +
> + ret = vmbus_negotiate_version(msginfo, vmbus_proto_version);

I think this code answers my earlier question: Upon resume, we negotiate the same
VMbus protocol version we had at time of hibernation, even if running on a newer
version of Hyper-V that might support newer protocol versions. Hence the offer
messages should not have any previously reserved fields now being used. A
comment to this effect would be useful.

> +
> + kfree(msginfo);
> +
> + if (ret != 0)
> + return ret;
> +
> + vmbus_request_offers();
> +
> + return 0;
> +}
> +
> static const struct acpi_device_id vmbus_acpi_device_ids[] = {
> {"VMBUS", 0},
> {"VMBus", 0},
> @@ -2052,6 +2087,10 @@ static int vmbus_acpi_add(struct acpi_device *device)
> };
> MODULE_DEVICE_TABLE(acpi, vmbus_acpi_device_ids);
>
> +static const struct dev_pm_ops vmbus_bus_pm = {
> + SET_SYSTEM_SLEEP_PM_OPS(vmbus_bus_suspend, vmbus_bus_resume)
> +};
> +
> static struct acpi_driver vmbus_acpi_driver = {
> .name = "vmbus",
> .ids = vmbus_acpi_device_ids,
> @@ -2059,6 +2098,7 @@ static int vmbus_acpi_add(struct acpi_device *device)
> .add = vmbus_acpi_add,
> .remove = vmbus_acpi_remove,
> },
> + .drv.pm = &vmbus_bus_pm,
> };
>
> static void hv_kexec_handler(void)
> --
> 1.8.3.1