On 2020/7/12 下午11:29, Alex Williamson wrote:

On Sun, 12 Jul 2020 22:49:21 +0800
Zhu Lingshan [off-list ref] wrote:

quoted

We used to detect assigned device via VFIO manipulated device
conters. This is less flexible consider VFIO is not the only
interface for assigned device. vDPA devices has dedicated
backed hardware as well. So this patch tries to detect
the assigned device 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.

No it doesn't, it only adds VFIO support to x86, but it removes it from
architecture neutral code.

Do you mean we should introduce a kvm_irq_bypass_add_producer and do 
kvm_arch_start_assignment( ) there?

Also a VFIO device does not necessarily
make use of the irqbypass manager, this depends on platform support and
enablement of this feature.

Yes, we should keep the VFIO part unchanged.

Thanks

   Therefore, NAK.  Thanks,

Alex
  

quoted

Signed-off-by: Zhu Lingshan <redacted>
---
  arch/x86/kvm/x86.c | 10 ++++++++--
  virt/kvm/vfio.c    |  2 --
  2 files changed, 8 insertions(+), 4 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,

diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
index 8fcbc50..111da52 100644
--- a/virt/kvm/vfio.c
+++ b/virt/kvm/vfio.c

@@ -226,7 +226,6 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
  		list_add_tail(&kvg->node, &kv->group_list);
  		kvg->vfio_group = vfio_group;
  
-		kvm_arch_start_assignment(dev->kvm);
  
  		mutex_unlock(&kv->lock);
  

@@ -254,7 +253,6 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
  				continue;
  
  			list_del(&kvg->node);
-			kvm_arch_end_assignment(dev->kvm);
  #ifdef CONFIG_SPAPR_TCE_IOMMU
  			kvm_spapr_tce_release_vfio_group(dev->kvm,
  							 kvg->vfio_group);