[1/2] KVM: x86: add start_assignment hook to kvm_x86_ops

Commit Message

Marcelo Tosatti May 6, 2021, 6:57 p.m. UTC

Add a start_assignment hook to kvm_x86_ops, which is called when 
kvm_arch_start_assignment is done.

The hook is required to update the wakeup vector of a sleeping vCPU
when a device is assigned to the guest.

Signed-off-by: Marcelo Tosatti <[e-mail]>

Comments

Sean Christopherson May 6, 2021, 7:54 p.m. UTC | #1

On Thu, May 06, 2021, Marcelo Tosatti wrote:
> Index: kvm/arch/x86/kvm/x86.c
> ===================================================================
> --- kvm.orig/arch/x86/kvm/x86.c
> +++ kvm/arch/x86/kvm/x86.c
> @@ -11295,7 +11295,11 @@ bool kvm_arch_can_dequeue_async_page_pre
>  
>  void kvm_arch_start_assignment(struct kvm *kvm)
>  {
> -	atomic_inc(&kvm->arch.assigned_device_count);
> +	int ret;
> +
> +	ret = atomic_inc_return(&kvm->arch.assigned_device_count);
> +	if (kvm_x86_ops.start_assignment)
> +		kvm_x86_ops.start_assignment(kvm, ret);

This can be a static_call(), just needs an entry in kvm-x86-ops.h.

>  }
>  EXPORT_SYMBOL_GPL(kvm_arch_start_assignment);
>  
> 
>

Patch

Index: kvm/arch/x86/include/asm/kvm_host.h
===================================================================
--- kvm.orig/arch/x86/include/asm/kvm_host.h
+++ kvm/arch/x86/include/asm/kvm_host.h
@@ -1322,6 +1322,7 @@  struct kvm_x86_ops {
 
 	int (*update_pi_irte)(struct kvm *kvm, unsigned int host_irq,
 			      uint32_t guest_irq, bool set);
+	void (*start_assignment)(struct kvm *kvm, int device_count);
 	void (*apicv_post_state_restore)(struct kvm_vcpu *vcpu);
 	bool (*dy_apicv_has_pending_interrupt)(struct kvm_vcpu *vcpu);
 
Index: kvm/arch/x86/kvm/svm/svm.c
===================================================================
--- kvm.orig/arch/x86/kvm/svm/svm.c
+++ kvm/arch/x86/kvm/svm/svm.c
@@ -4601,6 +4601,7 @@  static struct kvm_x86_ops svm_x86_ops __
 	.deliver_posted_interrupt = svm_deliver_avic_intr,
 	.dy_apicv_has_pending_interrupt = svm_dy_apicv_has_pending_interrupt,
 	.update_pi_irte = svm_update_pi_irte,
+	.start_assignment = NULL,
 	.setup_mce = svm_setup_mce,
 
 	.smi_allowed = svm_smi_allowed,
Index: kvm/arch/x86/kvm/vmx/vmx.c
===================================================================
--- kvm.orig/arch/x86/kvm/vmx/vmx.c
+++ kvm/arch/x86/kvm/vmx/vmx.c
@@ -7732,6 +7732,7 @@  static struct kvm_x86_ops vmx_x86_ops __
 	.nested_ops = &vmx_nested_ops,
 
 	.update_pi_irte = pi_update_irte,
+	.start_assignment = NULL,
 
 #ifdef CONFIG_X86_64
 	.set_hv_timer = vmx_set_hv_timer,
Index: kvm/arch/x86/kvm/x86.c
===================================================================
--- kvm.orig/arch/x86/kvm/x86.c
+++ kvm/arch/x86/kvm/x86.c
@@ -11295,7 +11295,11 @@  bool kvm_arch_can_dequeue_async_page_pre
 
 void kvm_arch_start_assignment(struct kvm *kvm)
 {
-	atomic_inc(&kvm->arch.assigned_device_count);
+	int ret;
+
+	ret = atomic_inc_return(&kvm->arch.assigned_device_count);
+	if (kvm_x86_ops.start_assignment)
+		kvm_x86_ops.start_assignment(kvm, ret);
 }
 EXPORT_SYMBOL_GPL(kvm_arch_start_assignment);