linux-kernel - Re: [PATCH 1/1] virt/kvm/iommu.c: Add leading zeros to device's BDF notation in debug messages

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Message-ID: <1380743896.2673.6.camel@ul30vt.home>
Date:	Wed, 02 Oct 2013 13:58:16 -0600
From:	Alex Williamson <alex.williamson@...hat.com>
To:	Andre Richter <andre.o.richter@...il.com>
Cc:	Gleb Natapov <gleb@...hat.com>,
	Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] virt/kvm/iommu.c: Add leading zeros to device's BDF
 notation in debug messages

On Wed, 2013-10-02 at 21:08 +0200, Andre Richter wrote:
> 2013/10/2 Alex Williamson <alex.williamson@...hat.com>:
> > On Wed, 2013-10-02 at 13:35 +0300, Gleb Natapov wrote:
> >> On Wed, Oct 02, 2013 at 12:23:26PM +0200, Andre Richter wrote:
> >> > When KVM (de)assigns PCI(e) devices to VMs, a debug message is printed
> >> > including the BDF notation of the respective device. Currently, the BDF
> >> > notation does not have the commonly used leading zeros. This produces
> >> > messages like "assign device 0:1:8.0", which look strange at first sight.
> >> >
> >> > The patch fixes this by exchanging the printk(KERN_DEBUG ...) with dev_info()
> >> > and also inserts "kvm" into the debug message, so that it is obvious where
> >> > the message comes from. Also reduces LoC.
> >> Legacy assigned device is deprecated, but this looks nice enough to
> >> apply. Alex can you glance at it?
> >
> > Seems ok to me, my only question would be why are we promoting this from
> > KERN_DEBUG to KERN_INFO.  We could use dev_dbg() to maintain the same
> > kernel log level.  A nice feature of either is that it prints out the
> > attached driver so we can see in dmesg whether the device is attached to
> > a host driver, nothing, or pci-stub.  Thanks,
> >
> > Alex
> 
> I made it dev_info() because on my test system, dev_dbg() did not show
> up in dmesg, whereas
> the original printk(KERN_DEBUG ...) did. I guess dev_dbg() was
> stripped due to compiling without DEBUG?
> Therefore, I found dev_info() to better mimic the original behavior. I
> can change it to dev_dbg() if you wish?

Ah, dev_dbg is dynamic.  I guess I don't really mind the change, host
drivers print out more.

Acked-by: Alex Williamson <alex.williamson@...hat.com>

> >
> >> >
> >> > Signed-off-by: Andre Richter <andre.o.richter@...il.com>
> >> > ---
> >> >  virt/kvm/iommu.c | 12 ++----------
> >> >  1 file changed, 2 insertions(+), 10 deletions(-)
> >> >
> >> > diff --git a/virt/kvm/iommu.c b/virt/kvm/iommu.c
> >> > index 72a130b..a3b1410 100644
> >> > --- a/virt/kvm/iommu.c
> >> > +++ b/virt/kvm/iommu.c
> >> > @@ -190,11 +190,7 @@ int kvm_assign_device(struct kvm *kvm,
> >> >
> >> >     pdev->dev_flags |= PCI_DEV_FLAGS_ASSIGNED;
> >> >
> >> > -   printk(KERN_DEBUG "assign device %x:%x:%x.%x\n",
> >> > -           assigned_dev->host_segnr,
> >> > -           assigned_dev->host_busnr,
> >> > -           PCI_SLOT(assigned_dev->host_devfn),
> >> > -           PCI_FUNC(assigned_dev->host_devfn));
> >> > +   dev_info(&pdev->dev, "kvm assign device\n");
> >> >
> >> >     return 0;
> >> >  out_unmap:
> >> > @@ -220,11 +216,7 @@ int kvm_deassign_device(struct kvm *kvm,
> >> >
> >> >     pdev->dev_flags &= ~PCI_DEV_FLAGS_ASSIGNED;
> >> >
> >> > -   printk(KERN_DEBUG "deassign device %x:%x:%x.%x\n",
> >> > -           assigned_dev->host_segnr,
> >> > -           assigned_dev->host_busnr,
> >> > -           PCI_SLOT(assigned_dev->host_devfn),
> >> > -           PCI_FUNC(assigned_dev->host_devfn));
> >> > +   dev_info(&pdev->dev, "kvm deassign device\n");
> >> >
> >> >     return 0;
> >> >  }
> >> > --
> >> > 1.8.1.2
> >>
> >> --
> >>                       Gleb.
> >
> >
> >
> --
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