On Mon, 20 Jul 2026 at 06:39, Akihiko Odaki <[email protected]> wrote: > > From: Oliver Upton <[email protected]> > > commit e9b152cb957c ("arm/arm64: kvm: Set vcpu->cpu to -1 on vcpu_put") > reset vcpu->cpu in order for the VGIC to determine if there was any vCPU > running at the time of access. The VGIC has gone through an entire > rewrite since then, and with commit 7d450e282171 ("KVM: arm/arm64: > vgic-new: Add userland access to VGIC dist registers") the user > accessors just grab all vCPU mutexes instead. > > Drop this remaining vestige such that kvm_arch_vcpu_load() can properly > detect a CPU migration. While at it, rework kvm_reset_vcpu() to do a > much more pedantic check that the provided vCPU is actually what's > running on the present CPU. > > Signed-off-by: Oliver Upton <[email protected]> > Signed-off-by: Akihiko Odaki <[email protected]>
Reviewed-by: Fuad Tabba <[email protected]> Cheers, /fuad > --- > arch/arm64/kvm/arm.c | 1 - > arch/arm64/kvm/reset.c | 16 +++++++++++----- > 2 files changed, 11 insertions(+), 6 deletions(-) > > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c > index a06ea39f57b1..72ce79ce4d5e 100644 > --- a/arch/arm64/kvm/arm.c > +++ b/arch/arm64/kvm/arm.c > @@ -749,7 +749,6 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) > kvm_arm_vmid_clear_active(); > > vcpu_clear_on_unsupported_cpu(vcpu); > - vcpu->cpu = -1; > } > > static void __kvm_arm_vcpu_power_off(struct kvm_vcpu *vcpu) > diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c > index b963fd975aac..6bfb21f00444 100644 > --- a/arch/arm64/kvm/reset.c > +++ b/arch/arm64/kvm/reset.c > @@ -190,7 +190,8 @@ static void kvm_vcpu_reset_sve(struct kvm_vcpu *vcpu) > void kvm_reset_vcpu(struct kvm_vcpu *vcpu) > { > struct vcpu_reset_state reset_state; > - bool loaded; > + struct kvm_vcpu *running; > + bool loaded = false; > u32 pstate; > > spin_lock(&vcpu->arch.mp_state_lock); > @@ -198,10 +199,16 @@ void kvm_reset_vcpu(struct kvm_vcpu *vcpu) > vcpu->arch.reset_state.reset = false; > spin_unlock(&vcpu->arch.mp_state_lock); > > - preempt_disable(); > - loaded = (vcpu->cpu != -1); > - if (loaded) > + guard(preempt)(); > + > + running = kvm_get_running_vcpu(); > + if (running) { > + if (KVM_BUG_ON(running != vcpu, vcpu->kvm)) > + return; > + > + loaded = true; > kvm_arch_vcpu_put(vcpu); > + } > > if (!kvm_arm_vcpu_sve_finalized(vcpu)) { > if (vcpu_has_feature(vcpu, KVM_ARM_VCPU_SVE)) > @@ -269,7 +276,6 @@ void kvm_reset_vcpu(struct kvm_vcpu *vcpu) > > if (loaded) > kvm_arch_vcpu_load(vcpu, smp_processor_id()); > - preempt_enable(); > } > > u32 kvm_get_pa_bits(struct kvm *kvm) > > -- > 2.55.0 > >
