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

On Thu, 2011-09-22 at 22:19 -0700, Jesse Barnes wrote:

On Thu, 22 Sep 2011 21:16:18 -0700
Jeff Kirsher [off-list ref] wrote:

quoted

On Wed, Sep 21, 2011 at 03:12, Jeff Kirsher
[off-list ref] wrote:

quoted

From: Greg Rose <redacted>

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 <redacted>
Signed-off-by: Jeff Kirsher <redacted>
---
 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!