Re: [PATCH 1/3] KVM: Emulation MSI-X mask bits for assigned devices

[Marcelo Tosatti <mtosatti@redhat.com>]

On Tue, Sep 28, 2010 at 05:44:10PM +0800, Sheng Yang wrote:
> This patch enable per-vector mask for assigned devices using MSI-X.
> 
> Signed-off-by: Sheng Yang <sheng@linux.intel.com>
> ---
>  arch/x86/kvm/x86.c       |    1 +
>  include/linux/kvm.h      |    9 ++++++++-
>  include/linux/kvm_host.h |    1 +
>  virt/kvm/assigned-dev.c  |   39 +++++++++++++++++++++++++++++++++++++++
>  4 files changed, 49 insertions(+), 1 deletions(-)
> 

>  #include <linux/slab.h>
> +#include <linux/irqnr.h>
> +
>  #include "irq.h"
>  
>  static struct kvm_assigned_dev_kernel *kvm_find_assigned_dev(struct list_head *head,
> @@ -666,6 +668,30 @@ msix_nr_out:
>  	return r;
>  }
>  
> +static void update_msix_mask(struct kvm_assigned_dev_kernel *assigned_dev,
> +			     int index)
> +{
> +	int irq;
> +
> +	if (!assigned_dev->dev->msix_enabled ||
> +	    !(assigned_dev->irq_requested_type & KVM_DEV_IRQ_HOST_MSIX))
> +		return;
> +
> +	irq = assigned_dev->host_msix_entries[index].vector;
> +
> +	ASSERT(irq != 0);
> +
> +	if (assigned_dev->guest_msix_entries[index].flags &
> +			KVM_ASSIGNED_MSIX_MASK)
> +		disable_irq(irq);
> +	else {
> +		enable_irq(irq);
> +		if (assigned_dev->guest_msix_entries[index].flags &
> +				KVM_ASSIGNED_MSIX_PENDING)
> +			schedule_work(&assigned_dev->interrupt_work);
> +	}
> +}
> +

Should flush the workqueue after disabling irq. As you say, the
schedule_work should be unnecessary.

Also must be careful with races.

>  static int kvm_vm_ioctl_set_msix_entry(struct kvm *kvm,
>  				       struct kvm_assigned_msix_entry *entry)
>  {
> @@ -688,6 +714,19 @@ static int kvm_vm_ioctl_set_msix_entry(struct kvm *kvm,
>  			adev->guest_msix_entries[i].entry = entry->entry;
>  			adev->guest_msix_entries[i].vector = entry->gsi;
>  			adev->host_msix_entries[i].entry = entry->entry;
> +			if ((entry->flags & KVM_MSIX_FLAG_MASK) &&
> +					!(adev->guest_msix_entries[i].flags &
> +					KVM_ASSIGNED_MSIX_MASK)) {
> +				adev->guest_msix_entries[i].flags |=
> +					KVM_ASSIGNED_MSIX_MASK;
> +				update_msix_mask(adev, i);
> +			} else if (!(entry->flags & KVM_MSIX_FLAG_MASK) &&
> +					(adev->guest_msix_entries[i].flags &
> +					KVM_ASSIGNED_MSIX_MASK)) {
> +				adev->guest_msix_entries[i].flags &=
> +					~KVM_ASSIGNED_MSIX_MASK;
> +				update_msix_mask(adev, i);
> +			}
>  			break;
>  		}
>  	if (i == adev->entries_nr) {
> -- 
> 1.7.0.1