thr3ads.net - Linux Virtualization - [PATCH 2/7] kvm/vfio: detect assigned device via irqbypass manager [Jul 2020]

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Michael S. Tsirkin

2020-Jul-12 21:06 UTC

[PATCH 2/7] kvm/vfio: detect assigned device via irqbypass manager

On Sun, Jul 12, 2020 at 10:49:21PM +0800, Zhu Lingshan
wrote:> 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.
> 
> Signed-off-by: Zhu Lingshan <lingshan.zhu at intel.com>

I think it's best to leave VFIO alone. Add appropriate APIs for VDPA,
worry about converting existing users later.
> ---
>  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);
> -- 
> 1.8.3.1

Jason Wang

2020-Jul-13 08:13 UTC

head link

[PATCH 2/7] kvm/vfio: detect assigned device via irqbypass manager

On 2020/7/13 ??5:06, Michael S. Tsirkin wrote:> On Sun, Jul 12, 2020 at 10:49:21PM +0800, Zhu Lingshan wrote:
>> 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.
>>
>> Signed-off-by: Zhu Lingshan <lingshan.zhu at intel.com>
>
> I think it's best to leave VFIO alone. Add appropriate APIs for VDPA,
> worry about converting existing users later.


Just to make sure I understand, did you mean:

1) introduce another bridge for vDPA

or

2) only detect vDPA via bypass manager? (we can leave VFIO code as is, 
then the assigned device counter may increase/decrease twice if VFIO use 
irq bypass manager which should be no harm).

Thanks

>
>> ---
>>   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);
>> -- 
>> 1.8.3.1

Michael S. Tsirkin

2020-Jul-13 10:52 UTC

head link

[PATCH 2/7] kvm/vfio: detect assigned device via irqbypass manager

On Mon, Jul 13, 2020 at 04:13:35PM +0800, Jason Wang
wrote:> 
> On 2020/7/13 ??5:06, Michael S. Tsirkin wrote:
> > On Sun, Jul 12, 2020 at 10:49:21PM +0800, Zhu Lingshan wrote:
> > > 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.
> > > 
> > > Signed-off-by: Zhu Lingshan <lingshan.zhu at intel.com>
> > 
> > I think it's best to leave VFIO alone. Add appropriate APIs for
VDPA,
> > worry about converting existing users later.
> 
> 
> 
> Just to make sure I understand, did you mean:
> 
> 1) introduce another bridge for vDPA
> 
> or
> 
> 2) only detect vDPA via bypass manager? (we can leave VFIO code as is, then
> the assigned device counter may increase/decrease twice if VFIO use irq
> bypass manager which should be no harm).
> 
> Thanks
2 is probably easier to justify. 1 would depend on the specific bridge
proposed.
> 
> > 
> > > ---
> > >   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);
> > > -- 
> > > 1.8.3.1

Michael S. Tsirkin

2020-Jul-14 09:03 UTC

head link

[PATCH 2/7] kvm/vfio: detect assigned device via irqbypass manager

On Tue, Jul 14, 2020 at 08:52:43AM +0800, Zhu, Lingshan
wrote:> 
> On 7/13/2020 6:52 PM, Michael S. Tsirkin wrote:
> 
>     On Mon, Jul 13, 2020 at 04:13:35PM +0800, Jason Wang wrote:
> 
>         On 2020/7/13 ??5:06, Michael S. Tsirkin wrote:
> 
>             On Sun, Jul 12, 2020 at 10:49:21PM +0800, Zhu Lingshan wrote:
> 
>                 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.
> 
>                 Signed-off-by: Zhu Lingshan <lingshan.zhu at
intel.com>
> 
>             I think it's best to leave VFIO alone. Add appropriate APIs
for VDPA,
>             worry about converting existing users later.
> 
> 
> 
>         Just to make sure I understand, did you mean:
> 
>         1) introduce another bridge for vDPA
> 
>         or
> 
>         2) only detect vDPA via bypass manager? (we can leave VFIO code as
is, then
>         the assigned device counter may increase/decrease twice if VFIO use
irq
>         bypass manager which should be no harm).
> 
>         Thanks
> 
>     2 is probably easier to justify. 1 would depend on the specific bridge
>     proposed.
> 
> Thanks Michael, so we should just drop changes in vfio, just increase /
decrease
> the counter in irq bypass manager. right?
> 
> Thanks
I don't see any issue with that.
> 
> 
>                 ---
>                   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);
>                 --
>                 1.8.3.1
>

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