From d5c48debcc4fbdd09e3e0871980b7ebf06ec6e07 Mon Sep 17 00:00:00 2001
From: Sean Christopherson <sean.j.christopherson@intel.com>
Date: Wed, 18 Dec 2019 13:55:17 -0800
Subject: [PATCH] KVM: Move initialization of preempt notifier to
kvm_vcpu_init()
Initialize the preempt notifier immediately in kvm_vcpu_init() to pave
the way for removing kvm_arch_vcpu_setup(), i.e. to allow arch specific
code to call vcpu_load() during kvm_arch_vcpu_create().
Back when preemption support was added, the location of the call to init
the preempt notifier was perfectly sane. The overall vCPU creation flow
featured a single arch specific hook and the preempt notifer was used
immediately after its initialization (by vcpu_load()). E.g.:
vcpu = kvm_arch_ops->vcpu_create(kvm, n);
if (IS_ERR(vcpu))
return PTR_ERR(vcpu);
preempt_notifier_init(&vcpu->preempt_notifier, &kvm_preempt_ops);
vcpu_load(vcpu);
r = kvm_mmu_setup(vcpu);
vcpu_put(vcpu);
if (r < 0)
goto free_vcpu;
Today, the call to preempt_notifier_init() is sandwiched between two
arch specific calls, kvm_arch_vcpu_create() and kvm_arch_vcpu_setup(),
which needlessly forces x86 (and possibly others?) to split its vCPU
creation flow. Init the preempt notifier prior to any arch specific
call so that each arch can independently decide how best to organize
its creation flow.
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
virt/kvm/kvm_main.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 44b4e86646435..1ddb6d4cfbfd0 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -348,6 +348,7 @@ static int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
kvm_vcpu_set_dy_eligible(vcpu, false);
vcpu->preempted = false;
vcpu->ready = false;
+ preempt_notifier_init(&vcpu->preempt_notifier, &kvm_preempt_ops);
r = kvm_arch_vcpu_init(vcpu);
if (r < 0)
@@ -2752,8 +2753,6 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
if (r)
goto vcpu_uninit;
- preempt_notifier_init(&vcpu->preempt_notifier, &kvm_preempt_ops);
-
r = kvm_arch_vcpu_setup(vcpu);
if (r)
goto vcpu_destroy;
--
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