KVM: x86: add start_assignment hook to kvm_x86_ops

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 <mtosatti@redhat.com>
Message-Id: <20210525134321.254128742@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index 3236410..e7bef91 100644 (file)
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -99,6 +99,7 @@ KVM_X86_OP_NULL(post_block)
 KVM_X86_OP_NULL(vcpu_blocking)
 KVM_X86_OP_NULL(vcpu_unblocking)
 KVM_X86_OP_NULL(update_pi_irte)
+KVM_X86_OP_NULL(start_assignment)
 KVM_X86_OP_NULL(apicv_post_state_restore)
 KVM_X86_OP_NULL(dy_apicv_has_pending_interrupt)
 KVM_X86_OP_NULL(set_hv_timer)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 55efbac..9c7ced0 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1352,6 +1352,7 @@ 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);
        void (*apicv_post_state_restore)(struct kvm_vcpu *vcpu);
        bool (*dy_apicv_has_pending_interrupt)(struct kvm_vcpu *vcpu);
 

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index bed7b53..98538b1 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -11504,7 +11504,8 @@ bool kvm_arch_can_dequeue_async_page_present(struct kvm_vcpu *vcpu)
 
 void kvm_arch_start_assignment(struct kvm *kvm)
 {
-       atomic_inc(&kvm->arch.assigned_device_count);
+       if (atomic_inc_return(&kvm->arch.assigned_device_count) == 1)
+               static_call_cond(kvm_x86_start_assignment)(kvm);
 }
 EXPORT_SYMBOL_GPL(kvm_arch_start_assignment);