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[RESEND v3 1/3] KVM: setup empty irq routing when create vm

Yi Wang posted 3 patches 1 year, 11 months ago
There is a newer version of this series
[RESEND v3 1/3] KVM: setup empty irq routing when create vm
Posted by Yi Wang 1 year, 11 months ago 
From: Yi Wang <foxywang@tencent.com>

Add a new function to setup empty irq routing in kvm path, which
can be invoded in non-architecture-specific functions. The difference
compared to the kvm_setup_empty_irq_routing() is this function just
alloc the empty irq routing and does not need synchronize srcu, as
we will call it in kvm_create_vm().

Using the new adding function, we can setup empty irq routing when
kvm_create_vm(), so that x86 and s390 no longer need to set
empty/dummy irq routing when creating an IRQCHIP 'cause it avoid
an synchronize_srcu.

Signed-off-by: Yi Wang <foxywang@tencent.com>
---
 include/linux/kvm_host.h |  1 +
 virt/kvm/irqchip.c       | 19 +++++++++++++++++++
 virt/kvm/kvm_main.c      |  4 ++++
 3 files changed, 24 insertions(+)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 4944136efaa2..e91525c0a4ea 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -2000,6 +2000,7 @@ int kvm_set_irq_routing(struct kvm *kvm,
 			const struct kvm_irq_routing_entry *entries,
 			unsigned nr,
 			unsigned flags);
+int kvm_setup_empty_irq_routing_lockless(struct kvm *kvm);
 int kvm_set_routing_entry(struct kvm *kvm,
 			  struct kvm_kernel_irq_routing_entry *e,
 			  const struct kvm_irq_routing_entry *ue);
diff --git a/virt/kvm/irqchip.c b/virt/kvm/irqchip.c
index 1e567d1f6d3d..90fc43bd0fe4 100644
--- a/virt/kvm/irqchip.c
+++ b/virt/kvm/irqchip.c
@@ -237,3 +237,22 @@ int kvm_set_irq_routing(struct kvm *kvm,
 
 	return r;
 }
+
+int kvm_setup_empty_irq_routing_lockless(struct kvm *kvm)
+{
+	struct kvm_irq_routing_table *new;
+	u32 i, j;
+
+	new = kzalloc(struct_size(new, map, 1), GFP_KERNEL_ACCOUNT);
+	if (!new)
+		return -ENOMEM;
+
+	new->nr_rt_entries = 1;
+	for (i = 0; i < KVM_NR_IRQCHIPS; i++)
+		for (j = 0; j < KVM_IRQCHIP_NUM_PINS; j++)
+			new->chip[i][j] = -1;
+
+	RCU_INIT_POINTER(kvm->irq_routing, new);
+
+	return 0;
+}
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 7db96875ac46..db1b13fc0502 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1242,6 +1242,10 @@ static struct kvm *kvm_create_vm(unsigned long type, const char *fdname)
 	if (r)
 		goto out_err;
 
+	r = kvm_setup_empty_irq_routing_lockless(kvm);
+	if (r)
+		goto out_err;
+
 	mutex_lock(&kvm_lock);
 	list_add(&kvm->vm_list, &vm_list);
 	mutex_unlock(&kvm_lock);
-- 
2.39.3
Re: [RESEND v3 1/3] KVM: setup empty irq routing when create vm
Posted by Yang, Weijiang 1 year, 11 months ago 
On 2/29/2024 2:53 PM, Yi Wang wrote:
> From: Yi Wang <foxywang@tencent.com>
>
> Add a new function to setup empty irq routing in kvm path, which
> can be invoded in non-architecture-specific functions. The difference
> compared to the kvm_setup_empty_irq_routing() is this function just
> alloc the empty irq routing and does not need synchronize srcu, as
> we will call it in kvm_create_vm().
>
> Using the new adding function, we can setup empty irq routing when
> kvm_create_vm(), so that x86 and s390 no longer need to set
> empty/dummy irq routing when creating an IRQCHIP 'cause it avoid
> an synchronize_srcu.
>
> Signed-off-by: Yi Wang <foxywang@tencent.com>
> ---
>   include/linux/kvm_host.h |  1 +
>   virt/kvm/irqchip.c       | 19 +++++++++++++++++++
>   virt/kvm/kvm_main.c      |  4 ++++
>   3 files changed, 24 insertions(+)
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 4944136efaa2..e91525c0a4ea 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -2000,6 +2000,7 @@ int kvm_set_irq_routing(struct kvm *kvm,
>   			const struct kvm_irq_routing_entry *entries,
>   			unsigned nr,
>   			unsigned flags);
> +int kvm_setup_empty_irq_routing_lockless(struct kvm *kvm);
>   int kvm_set_routing_entry(struct kvm *kvm,
>   			  struct kvm_kernel_irq_routing_entry *e,
>   			  const struct kvm_irq_routing_entry *ue);
> diff --git a/virt/kvm/irqchip.c b/virt/kvm/irqchip.c
> index 1e567d1f6d3d..90fc43bd0fe4 100644
> --- a/virt/kvm/irqchip.c
> +++ b/virt/kvm/irqchip.c
> @@ -237,3 +237,22 @@ int kvm_set_irq_routing(struct kvm *kvm,
>   
>   	return r;
>   }
> +
> +int kvm_setup_empty_irq_routing_lockless(struct kvm *kvm)
> +{
> +	struct kvm_irq_routing_table *new;
> +	u32 i, j;
> +
> +	new = kzalloc(struct_size(new, map, 1), GFP_KERNEL_ACCOUNT);
> +	if (!new)
> +		return -ENOMEM;
> +
> +	new->nr_rt_entries = 1;
> +	for (i = 0; i < KVM_NR_IRQCHIPS; i++)
> +		for (j = 0; j < KVM_IRQCHIP_NUM_PINS; j++)
> +			new->chip[i][j] = -1;

Maybe it looks nicer by:
size = sizeof(int) * KVM_NR_IRQCHIPS *KVM_IRQCHIP_NUM_PINS;
memset(new->chip, -1, size);

> +
> +	RCU_INIT_POINTER(kvm->irq_routing, new);
> +
> +	return 0;
> +}
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 7db96875ac46..db1b13fc0502 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1242,6 +1242,10 @@ static struct kvm *kvm_create_vm(unsigned long type, const char *fdname)
>   	if (r)
>   		goto out_err;
>   
> +	r = kvm_setup_empty_irq_routing_lockless(kvm);
> +	if (r)
> +		goto out_err;
> +
>   	mutex_lock(&kvm_lock);
>   	list_add(&kvm->vm_list, &vm_list);
>   	mutex_unlock(&kvm_lock);
Re: [RESEND v3 1/3] KVM: setup empty irq routing when create vm
Posted by Yi Wang 1 year, 11 months ago 
On Fri, Mar 8, 2024 at 12:06 PM Yang, Weijiang <weijiang.yang@intel.com> wrote:
>
> On 2/29/2024 2:53 PM, Yi Wang wrote:
> > From: Yi Wang <foxywang@tencent.com>

> > +
> > +int kvm_setup_empty_irq_routing_lockless(struct kvm *kvm)
> > +{
> > +     struct kvm_irq_routing_table *new;
> > +     u32 i, j;
> > +
> > +     new = kzalloc(struct_size(new, map, 1), GFP_KERNEL_ACCOUNT);
> > +     if (!new)
> > +             return -ENOMEM;
> > +
> > +     new->nr_rt_entries = 1;
> > +     for (i = 0; i < KVM_NR_IRQCHIPS; i++)
> > +             for (j = 0; j < KVM_IRQCHIP_NUM_PINS; j++)
> > +                     new->chip[i][j] = -1;
>
> Maybe it looks nicer by:
> size = sizeof(int) * KVM_NR_IRQCHIPS *KVM_IRQCHIP_NUM_PINS;
> memset(new->chip, -1, size);
>

It seems better, I'll update this patch. Thx a lot!

> > +
> > +     RCU_INIT_POINTER(kvm->irq_routing, new);
> > +
> > +     return 0;

>


---
Best wishes
Yi Wang
Re: [RESEND v3 1/3] KVM: setup empty irq routing when create vm
Posted by Dongli Zhang 1 year, 11 months ago 

On 2/28/24 22:53, Yi Wang wrote:
> From: Yi Wang <foxywang@tencent.com>
> 
> Add a new function to setup empty irq routing in kvm path, which
> can be invoded in non-architecture-specific functions. The difference

:s/invoded/invoked/

Dongli Zhang
Re: [RESEND v3 1/3] KVM: setup empty irq routing when create vm
Posted by Yi Wang 1 year, 11 months ago 
On Thu, Feb 29, 2024 at 6:15 PM Dongli Zhang <dongli.zhang@oracle.com> wrote:
>
>
>
> On 2/28/24 22:53, Yi Wang wrote:
> > From: Yi Wang <foxywang@tencent.com>
> >
> > Add a new function to setup empty irq routing in kvm path, which
> > can be invoded in non-architecture-specific functions. The difference
>
> :s/invoded/invoked/

Thanks for pointing this out.

Sean, Oliver, Christian, Do you have any other thoughts? Any
suggestions are appreciated.

>
> Dongli Zhang



-- 
---
Best wishes
Yi Wang

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