On Wed, Oct 20, 2010 at 04:26:30PM +0800, Sheng Yang wrote:
> The feature wouldn't be enabled until later patch set msix_flags_enabled. It
> would be enabled along with mask support in kernel.
> 
> Signed-off-by: Sheng Yang <sh...@linux.intel.com>
> ---
>  arch/x86/include/asm/kvm_host.h |    2 ++
>  include/linux/kvm.h             |    6 +++++-
>  include/linux/kvm_host.h        |    1 +
>  virt/kvm/assigned-dev.c         |   39 
> +++++++++++++++++++++++++++++++++++++++
>  4 files changed, 47 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index e209078..2bb69ba 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -456,6 +456,8 @@ struct kvm_arch {
>       /* fields used by HYPER-V emulation */
>       u64 hv_guest_os_id;
>       u64 hv_hypercall;
> +
> +     bool msix_flags_enabled;
>  };
>  
>  struct kvm_vm_stat {
> diff --git a/include/linux/kvm.h b/include/linux/kvm.h
> index 919ae53..a699ec9 100644
> --- a/include/linux/kvm.h
> +++ b/include/linux/kvm.h
> @@ -787,11 +787,15 @@ struct kvm_assigned_msix_nr {
>  };
>  
>  #define KVM_MAX_MSIX_PER_DEV         256
> +
> +#define KVM_MSIX_FLAG_MASK   1
> +
>  struct kvm_assigned_msix_entry {
>       __u32 assigned_dev_id;
>       __u32 gsi;
>       __u16 entry; /* The index of entry in the MSI-X table */
> -     __u16 padding[3];
> +     __u16 flags;
> +     __u16 padding[2];
>  };
>  
>  #endif /* __LINUX_KVM_H */
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 30f83cd..81a6284 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -438,6 +438,7 @@ struct kvm_irq_ack_notifier {
>  };
>  
>  #define KVM_ASSIGNED_MSIX_PENDING            0x1
> +#define KVM_ASSIGNED_MSIX_MASK                       0x2
>  struct kvm_guest_msix_entry {
>       u32 vector;
>       u16 entry;
> diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c
> index 7c98928..bf96ea7 100644
> --- a/virt/kvm/assigned-dev.c
> +++ b/virt/kvm/assigned-dev.c
> @@ -666,11 +666,35 @@ msix_nr_out:
>       return r;
>  }
>  
> +static void update_msix_mask(struct kvm_assigned_dev_kernel *assigned_dev,
> +                          int index)
> +{
> +     int irq;
> +     struct irq_desc *desc;
> +
> +     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;
> +     BUG_ON(irq == 0);
> +     desc = irq_to_desc(irq);
> +     BUG_ON(!desc->msi_desc);
> +
> +     if (assigned_dev->guest_msix_entries[index].flags &
> +                     KVM_ASSIGNED_MSIX_MASK) {
> +             desc->chip->mask(irq);
> +             flush_work(&assigned_dev->interrupt_work);
> +     } else
> +             desc->chip->unmask(irq);
> +}

Bypassing irq handling code like this is wrong (see all the state
keeping in kernel/irq/handle.c).

You need a guarantee that MSIX per-vector mask is used for
disable_irq/enable_irq, right? I can't see how this provides it.

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