On Wed, Nov 03, 2010 at 09:11:13AM +0100, Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
>
> This improves the IRQ forwarding for assigned devices: By using the
> kernel's threaded IRQ scheme, we can get rid of the latency-prone work
> queue and simplify the code in the same run.
>
> Moreover, we no longer have to hold assigned_dev_lock while raising the
> guest IRQ, which can be a lenghty operation as we may have to iterate
> over all VCPUs. The lock is now only used for synchronizing masking vs.
> unmasking of INTx-type IRQs, thus is renames to intx_lock.
>
> Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
> ---
> include/linux/kvm_host.h | 12 +----
> virt/kvm/assigned-dev.c | 106 ++++++++++++++-------------------------------
> 2 files changed, 35 insertions(+), 83 deletions(-)
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index bcf71c7..eaacb5d 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -457,16 +457,8 @@ struct kvm_irq_ack_notifier {
> void (*irq_acked)(struct kvm_irq_ack_notifier *kian);
> };
>
> -#define KVM_ASSIGNED_MSIX_PENDING 0x1
> -struct kvm_guest_msix_entry {
> - u32 vector;
> - u16 entry;
> - u16 flags;
> -};
> -
> struct kvm_assigned_dev_kernel {
> struct kvm_irq_ack_notifier ack_notifier;
> - struct work_struct interrupt_work;
> struct list_head list;
> int assigned_dev_id;
> int host_segnr;
> @@ -477,13 +469,13 @@ struct kvm_assigned_dev_kernel {
> bool host_irq_disabled;
> struct msix_entry *host_msix_entries;
> int guest_irq;
> - struct kvm_guest_msix_entry *guest_msix_entries;
> + struct msix_entry *guest_msix_entries;
> unsigned long irq_requested_type;
> int irq_source_id;
> int flags;
> struct pci_dev *dev;
> struct kvm *kvm;
> - spinlock_t assigned_dev_lock;
> + spinlock_t intx_lock;
> };
>
> struct kvm_irq_mask_notifier {
> diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c
> index ecc4419..d0b07ea 100644
> --- a/virt/kvm/assigned-dev.c
> +++ b/virt/kvm/assigned-dev.c
> @@ -55,58 +55,31 @@ static int find_index_from_host_irq(struct kvm_assigned_dev_kernel
> return index;
> }
>
> -static void kvm_assigned_dev_interrupt_work_handler(struct work_struct *work)
> +static irqreturn_t kvm_assigned_dev_thread(int irq, void *dev_id)
> {
> - struct kvm_assigned_dev_kernel *assigned_dev;
> - int i;
> + struct kvm_assigned_dev_kernel *assigned_dev = dev_id;
> + u32 vector;
> + int index;
>
> - assigned_dev = container_of(work, struct kvm_assigned_dev_kernel,
> - interrupt_work);
> + if (assigned_dev->irq_requested_type & KVM_DEV_IRQ_HOST_INTX) {
> + spin_lock(&assigned_dev->intx_lock);
> + disable_irq_nosync(irq);
> + assigned_dev->host_irq_disabled = true;
> + spin_unlock(&assigned_dev->intx_lock);
> + }
Shouldnt this happen in the hardirq handler? Otherwise host will receive
interrupts between ->eoi and this point.
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