Re: [PATCH 2/2] KVM: Use pci_store/load_saved_state() around VM device usage

Jan Kiszka
2011-04-15T20:03:31Z

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On 2011-04-15 21:54, Alex Williamson wrote:
> Store the device saved state so that we can reload the device back
> to the original state when it's unassigned. This has the benefit
> that the state survives across pci_reset_function() calls via
> the PCI sysfs reset interface while the VM is using the device.
>
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> ---
>
> include/linux/kvm_host.h | 1 +
> virt/kvm/assigned-dev.c | 8 +++++---
> 2 files changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index ab42855..d8a1d18 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -513,6 +513,7 @@ struct kvm_assigned_dev_kernel {
> struct kvm *kvm;
> spinlock_t intx_lock;
> char irq_name[32];
> + void *pci_saved_state;
> };
>
> struct kvm_irq_mask_notifier {
> diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c
> index ae72ae6..66c6ccd 100644
> --- a/virt/kvm/assigned-dev.c
> +++ b/virt/kvm/assigned-dev.c
> @@ -197,7 +197,9 @@ static void kvm_free_assigned_device(struct kvm *kvm,
> {
> kvm_free_assigned_irq(kvm, assigned_dev);
>
> - __pci_reset_function(assigned_dev->dev);
> + pci_reset_function(assigned_dev->dev);
> + pci_load_and_free_saved_state(assigned_dev->dev,
> + &assigned_dev->pci_saved_state);
> pci_restore_state(assigned_dev->dev);
>
> pci_release_regions(assigned_dev->dev);
> @@ -516,7 +518,7 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
>
> pci_reset_function(dev);
> pci_save_state(dev);
> -
> + match->pci_saved_state = pci_store_saved_state(dev);
> match->assigned_dev_id = assigned_dev->assigned_dev_id;
> match->host_segnr = assigned_dev->segnr;
> match->host_busnr = assigned_dev->busnr;
> @@ -546,7 +548,7 @@ out:
> mutex_unlock(&kvm->lock);
> return r;
> out_list_del:
> - pci_restore_state(dev);
> + pci_load_and_free_saved_state(dev, &match->pci_saved_state);

Don't you need to keep the balance, ie. load_and_free, then restore?

> list_del(&match->list);
> pci_release_regions(dev);
> out_disable:
>

Thanks for addressing the issue!

Jan

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