linux-kernel - RE: [PATCH v2 6/7] Drivers: hv: vmbus: Suspend/resume the vmbus itself for hibernation

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Date:   Wed, 7 Aug 2019 23:09:09 +0000
From:   Dexuan Cui <decui@...rosoft.com>
To:     "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>,
        "sashal@...nel.org" <sashal@...nel.org>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        KY Srinivasan <kys@...rosoft.com>,
        Michael Kelley <mikelley@...rosoft.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v2 6/7] Drivers: hv: vmbus: Suspend/resume the vmbus
 itself for hibernation

> From: Dexuan Cui <decui@...rosoft.com>
> Sent: Wednesday, July 31, 2019 10:52 AM
> To: linux-hyperv@...r.kernel.org; gregkh@...uxfoundation.org; Stephen
> @@ -2050,6 +2095,10 @@ 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)
> +};

It turns out this " SET_SYSTEM_SLEEP_PM_OPS" should be changed to
"SET_NOIRQ_SYSTEM_SLEEP_PM_OPS" to make NIC SR-IOV work with
hibernation.

This is because the "pci_dev_pm_ops" uses the "noirq" callbacks. 
In the resume path, the "noirq" restore callback runs before the non-noirq
callbacks, meaning the vmbus_bus_resume() and the pci-hyperv's .resume()
must also run via the "noirq" callbacks.

Similarly, I also need to make the same change in this patch:
[PATCH v2 7/7] Drivers: hv: vmbus: Implement suspend/resume for VSC drivers for hibernation

BTW, I'd like to change the print_hex_dump_debug() to print_hex_dump() in this patch:
[PATCH v2 5/7] Drivers: hv: vmbus: Ignore the offers when resuming from hibernation

print_hex_dump_debug() outputs nothing unless we enable the dyndbg. 
This is not good as we do want see the error messages here, if there is an error.

I'll do more tests and post a v3 of the patchset.

Thanks,
-- Dexuan