From mboxrd@z Thu Jan  1 00:00:00 1970
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: Re: Device Reset on Nvidia GPUs
Date: Fri, 15 Nov 2013 09:40:04 -0500
Message-ID: <20131115144004.GA28448@phenom.dumpdata.com>
References: <87b7d4387d7ab0bbb220efa864170381@mail.shatteredsilicon.net>
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To: Gordan Bobic <gordan@bobich.net>
Cc: xen-devel@lists.xen.org, Stefano Stabellini <stefano.stabellini@eu.citrix.com>
List-Id: xen-devel@lists.xenproject.org

On Fri, Nov 15, 2013 at 02:29:39PM +0000, Gordan Bobic wrote:
> On Fri, 15 Nov 2013 14:27:21 +0000, Stefano Stabellini
> <stefano.stabellini@eu.citrix.com> wrote:
> >On Fri, 15 Nov 2013, Gordan Bobic wrote:
> >>I've noticed that nouveau driver has a sysfs reset implemented
> >>(although I'm not sure whether it is just a stub or whether it
> >>does anything).
> >>
> >>Now, I fully understand that this is not actually necessary,
> >>based purely on empirical evidence:
> >>
> >>My ATI cards reliably crash the host when the domU the are passed
> >>to is rebooted, and the xen-pciback driver does have the sysfs
> >>reset implemented for ATI cards.
> >>
> >>OTOH, my (modified) Nvidia cards handle domU reboots perfectly
> >>and the xen-pciback driver has no sysfs reset implementation
> >>for those.
> >>
> >>So I'm kind of torn between:
> >>1) It's not broken so don't even think about trying to fix it.
> >>2) Since FOSS reset implementation seems to exist, it might be
> >>handy to port it into the xen-pciback feature list (caveat:
> >>this may impact 1), which would be embarrasing).
> >>
> >>Thoughts?
> >
> >libxl is capable of using the sysfs reset node, so there shouldn't be
> >any needed for porting the reset code to pciback
> 
> Not quite - when the device is owned by xen-pciback, there is
> no reset node. When it is owned by nouveau, the reset node in
> sysfs is there.

Sure, but pciback does the reset:


      /* 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");  
        else {                                                                  
                dev_dbg(&dev->dev, "resetting (FLR, D3, etc) the device\n");    
                __pci_reset_function_locked(dev);                               
                pci_restore_state(dev);                                         
        }                                                              

The pci_reset_function(..) - the non-locked variant) is called when you
do 'reset' to the SysFS.

Unless the nouveau driver does some extra 'reset'?
> 
> Gordan
> 
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