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

[Jan Kiszka <jan.kiszka@web.de>]

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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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