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Date: Thu, 05 Jan 2012 13:58:50 -0500
From: Don Dutile <ddutile@...hat.com>
To: Ian Campbell <Ian.Campbell@...rix.com>
CC: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"jbarnes@...tuousgeek.org" <jbarnes@...tuousgeek.org>,
"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.com>
Subject: Re: [Xen-devel] [PATCH 2/5] xen/pciback: Support pci_reset_function,
aka FLR or D3 support.
On 01/05/2012 05:24 AM, Ian Campbell wrote:
> On Thu, 2012-01-05 at 00:46 +0000, Konrad Rzeszutek Wilk wrote:
>> We use the __pci_reset_function_locked to perform the action.
>> Also on attaching ("bind") and detaching ("unbind") we save and
>> restore the configuration states. When the device is disconnected
>> from a guest we use the "pci_reset_function" to also reset the
>> device before being passed to another guest.
>
> Currently I thought the toolstack was supposed to do the reset (by
> writing to the reset node in sysfs) as it was (de)assigning devices
> to/from guests. That's not to say that there isn't an argument for
> preferring to do it kernels side but it would be interesting to make
> that argument explicitly.
>
> I guess the toolstack doesn't currently save/restore the configuration
> state, could it though? I guess the state is all available in sysfs. On
pci_reset_function() saves the config state before doing a fcn-level reset.
the libvirt toolstack handles the unbind/reset/bind functionality
and is used by kvm for it's device assignment.
> the other hand the kernel provides us with a very handy function which
> Just Does It...
>
> Ian.
>
>>
>> Signed-off-by: Konrad Rzeszutek Wilk<konrad.wilk@...cle.com>
>> ---
>> drivers/xen/xen-pciback/pci_stub.c | 41 +++++++++++++++++++++++++++++++++--
>> drivers/xen/xen-pciback/pciback.h | 1 +
>> 2 files changed, 39 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
>> index 8f06e1e..0ce0dc6 100644
>> --- a/drivers/xen/xen-pciback/pci_stub.c
>> +++ b/drivers/xen/xen-pciback/pci_stub.c
>> @@ -85,19 +85,34 @@ static struct pcistub_device *pcistub_device_alloc(struct pci_dev *dev)
>> static void pcistub_device_release(struct kref *kref)
>> {
>> struct pcistub_device *psdev;
>> + struct xen_pcibk_dev_data *dev_data;
>>
>> psdev = container_of(kref, struct pcistub_device, kref);
>> + dev_data = pci_get_drvdata(psdev->dev);
>>
>> dev_dbg(&psdev->dev->dev, "pcistub_device_release\n");
>>
>> xen_unregister_device_domain_owner(psdev->dev);
>>
>> - /* Clean-up the device */
>> + /* Call the reset function which does not take lock as this
>> + * is called from "unbind" which takes a device_lock mutex.
>> + */
>> + __pci_reset_function_locked(psdev->dev);
>> + if (pci_load_and_free_saved_state(psdev->dev,
>> + &dev_data->pci_saved_state)) {
>> + dev_dbg(&psdev->dev->dev, "Could not reload PCI state\n");
>> + } else
>> + pci_restore_state(psdev->dev);
>> +
>> + /* Disable the device */
>> xen_pcibk_reset_device(psdev->dev);
>> +
>> + kfree(dev_data);
>> + pci_set_drvdata(psdev->dev, NULL);
>> +
>> + /* Clean-up the device */
>> xen_pcibk_config_free_dyn_fields(psdev->dev);
>> xen_pcibk_config_free_dev(psdev->dev);
>> - kfree(pci_get_drvdata(psdev->dev));
>> - pci_set_drvdata(psdev->dev, NULL);
>>
>> pci_dev_put(psdev->dev);
>>
>> @@ -230,7 +245,17 @@ void pcistub_put_pci_dev(struct pci_dev *dev)
>> /* Cleanup our device
>> * (so it's ready for the next domain)
>> */
>> +
>> + /* This is OK - we are running from workqueue context
>> + * and want to inhibit the user from fiddling with 'reset'
>> + */
>> + pci_reset_function(dev);
>> + pci_restore_state(psdev->dev);
>> +
>> + /* This disables the device. */
>> xen_pcibk_reset_device(found_psdev->dev);
>> +
>> + /* And cleanup up our emulated fields. */
>> xen_pcibk_config_free_dyn_fields(found_psdev->dev);
>> xen_pcibk_config_reset_dev(found_psdev->dev);
>>
>> @@ -325,6 +350,16 @@ static int __devinit pcistub_init_device(struct pci_dev *dev)
>> if (err)
>> goto config_release;
>>
>> + dev_dbg(&dev->dev, "reseting (FLR, D3, etc) the device\n");
>> + __pci_reset_function_locked(dev);
>> +
>> + /* We need the device active to save the state. */
>> + dev_dbg(&dev->dev, "save state of device\n");
>> + pci_save_state(dev);
>> + dev_data->pci_saved_state = pci_store_saved_state(dev);
>> + if (!dev_data->pci_saved_state)
>> + dev_err(&dev->dev, "Could not store PCI conf saved state!\n");
>> +
>> /* Now disable the device (this also ensures some private device
>> * data is setup before we export)
>> */
>> diff --git a/drivers/xen/xen-pciback/pciback.h b/drivers/xen/xen-pciback/pciback.h
>> index e9b4011..a7def01 100644
>> --- a/drivers/xen/xen-pciback/pciback.h
>> +++ b/drivers/xen/xen-pciback/pciback.h
>> @@ -41,6 +41,7 @@ struct xen_pcibk_device {
>>
>> struct xen_pcibk_dev_data {
>> struct list_head config_fields;
>> + struct pci_saved_state *pci_saved_state;
>> unsigned int permissive:1;
>> unsigned int warned_on_write:1;
>> unsigned int enable_intx:1;
>
>
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