On Thu, 16 Jul 2020 19:23:45 +0800
Zhu Lingshan <lingshan.zhu@xxxxxxxxx> wrote:
> vDPA devices has dedicated backed hardware like
> passthrough-ed devices. Then it is possible to setup irq
> offloading to vCPU for vDPA devices. Thus this patch tries to
> manipulated assigned device counters via irqbypass manager.
>
> We will increase/decrease the assigned device counter in kvm/x86.
> Both vDPA and VFIO would go through this code path.
>
> This code path only affect x86 for now.
>
> Signed-off-by: Zhu Lingshan <lingshan.zhu@xxxxxxxxx>
> Suggested-by: Jason Wang <jasowang@xxxxxxxxxx>
> ---
> arch/x86/kvm/x86.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 00c88c2..20c07d3 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -10624,11 +10624,17 @@ int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *cons,
> {
> struct kvm_kernel_irqfd *irqfd =
> container_of(cons, struct kvm_kernel_irqfd, consumer);
> + int ret;
>
> irqfd->producer = prod;
> + kvm_arch_start_assignment(irqfd->kvm);
> + ret = kvm_x86_ops.update_pi_irte(irqfd->kvm,
> + prod->irq, irqfd->gsi, 1);
> +
> + if (ret)
> + kvm_arch_end_assignment(irqfd->kvm);
>
> - return kvm_x86_ops.update_pi_irte(irqfd->kvm,
> - prod->irq, irqfd->gsi, 1);
> + return ret;
> }
>
> void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *cons,
Why isn't there a matching end-assignment in the del_producer path? It
seems this only goes one-way, what happens when a device is
hot-unplugged from the VM or the device interrupt configuration changes.
This will still break vfio if it's not guaranteed to be symmetric.
Thanks,
Alex
