Re: [net-next 1/8] pci: Add flag indicating device has been assigned by KVM

[Jeff Kirsher <jeffrey.t.kirsher@intel.com>]

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On Thu, 2011-09-22 at 22:19 -0700, Jesse Barnes wrote:
> On Thu, 22 Sep 2011 21:16:18 -0700
> Jeff Kirsher <jeffrey.t.kirsher@intel.com> wrote:
> 
> > On Wed, Sep 21, 2011 at 03:12, Jeff Kirsher
> > <jeffrey.t.kirsher@intel.com> wrote:
> > > From: Greg Rose <gregory.v.rose@intel.com>
> > >
> > > Device drivers that create and destroy SR-IOV virtual functions via
> > > calls to pci_enable_sriov() and pci_disable_sriov can cause
> > > catastrophic failures if they attempt to destroy VFs while they are
> > > assigned to guest virtual machines.  By adding a flag for use by
> > > the KVM module to indicate that a device is assigned a device
> > > driver can check that flag and avoid destroying VFs while they are
> > > assigned and avoid system failures.
> > >
> > > Signed-off-by: Greg Rose <gregory.v.rose@intel.com>
> > > Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
> > > ---
> > >  include/linux/pci.h     |    2 ++
> > >  virt/kvm/assigned-dev.c |    2 ++
> > >  virt/kvm/iommu.c        |    4 ++++
> > >  3 files changed, 8 insertions(+), 0 deletions(-)
> > >
> > > diff --git a/include/linux/pci.h b/include/linux/pci.h
> > > index f27893b..4f511da 100644
> > > --- a/include/linux/pci.h
> > > +++ b/include/linux/pci.h
> > > @@ -174,6 +174,8 @@ enum pci_dev_flags {
> > >        PCI_DEV_FLAGS_MSI_INTX_DISABLE_BUG = (__force
> > > pci_dev_flags_t) 1, /* Device configuration is irrevocably lost if
> > > disabled into D3 */ PCI_DEV_FLAGS_NO_D3 = (__force pci_dev_flags_t)
> > > 2,
> > > +       /* Provide indication device is assigned by KVM */
> > > +       PCI_DEV_FLAGS_ASSIGNED = (__force pci_dev_flags_t) 4,
> > >  };
> > >
> > >  enum pci_irq_reroute_variant {
> > > diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c
> > > index 4e9eaeb..eaf3a50 100644
> > > --- a/virt/kvm/assigned-dev.c
> > > +++ b/virt/kvm/assigned-dev.c
> > > @@ -205,6 +205,8 @@ static void kvm_free_assigned_device(struct kvm
> > > *kvm, else
> > >                pci_restore_state(assigned_dev->dev);
> > >
> > > +       assigned_dev->dev->dev_flags &= ~PCI_DEV_FLAGS_ASSIGNED;
> > > +
> > >        pci_release_regions(assigned_dev->dev);
> > >        pci_disable_device(assigned_dev->dev);
> > >        pci_dev_put(assigned_dev->dev);
> > > diff --git a/virt/kvm/iommu.c b/virt/kvm/iommu.c
> > > index 78c80f6..967aba1 100644
> > > --- a/virt/kvm/iommu.c
> > > +++ b/virt/kvm/iommu.c
> > > @@ -187,6 +187,8 @@ int kvm_assign_device(struct kvm *kvm,
> > >                        goto out_unmap;
> > >        }
> > >
> > > +       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,
> > > @@ -215,6 +217,8 @@ int kvm_deassign_device(struct kvm *kvm,
> > >
> > >        iommu_detach_device(domain, &pdev->dev);
> > >
> > > +       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,
> > > --
> > > 1.7.6.2
> > 
> > Jesse/Konrad/Ian-
> > 
> > I sent this patch out as part of a pull request for David Miller's
> > net-next tree.  I know that Greg sent this originally out to the
> > linux-pci mailing list as a RFC. Since Greg also has a patch against
> > ixgbe which implemented this flag, I sent both patches for inclusion
> > into David Miller's net-next.
> > 
> > Dave is wanting to ensure that the PCI maintainers have reviewed this
> > and are ok with it before pulls my series of patches.
> 
> Yeah I think I looked at this one in the past, my ack must have been
> dropped.  You can add it if you want.
> 
> Jesse

Thanks Jesse!

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