Messages in this thread | | | Date | Thu, 26 Sep 2019 13:35:04 +0200 (CEST) | From | Miroslav Benes <> | Subject | Re: [RFC patch 14/15] workpending: Provide infrastructure for work before entering a guest |
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> --- a/include/linux/entry-common.h > +++ b/include/linux/entry-common.h
[...]
> +#define EXIT_TO_GUESTMODE_WORK \ > + (_TIF_NEED_RESCHED | _TIF_SIGPENDING | _TIF_NOTIFY_RESUME | \ > + ARCH_EXIT_TO_GUESTMODE_WORK)
[...]
> --- a/kernel/entry/common.c > +++ b/kernel/entry/common.c > > +int core_exit_to_guestmode_work(struct kvm *kvm, struct kvm_vcpu *vcpu, > + unsigned long ti_work) > +{ > + /* > + * Before returning to guest mode handle all pending work > + */ > + if (ti_work & _TIF_SIGPENDING) { > + vcpu->run->exit_reason = KVM_EXIT_INTR; > + vcpu->stat.signal_exits++; > + return -EINTR; > + } > + > + if (ti_work & _TIF_NEED_RESCHED) { > + srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx); > + schedule(); > + vcpu->srcu_idx = srcu_read_lock(&kvm->srcu); > + } > + > + if (ti_work & _TIF_PATCH_PENDING) { > + srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx); > + klp_update_patch_state(current); > + vcpu->srcu_idx = srcu_read_lock(&kvm->srcu); > + }
If I am reading the code correctly, _TIF_PATCH_PENDING is not a part of EXIT_TO_GUESTMODE_WORK, so the handling code here would not be called on any arch as of now.
I also think that _TIF_PATCH_PENDING must not be handled here generally. It could break consistency guarantees when live patching KVM (and we do that from time to time).
Adding live-patching ML to CC.
Miroslav
> + if (ti_work & _TIF_NOTIFY_RESUME) { > + srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx); > + clear_thread_flag(TIF_NOTIFY_RESUME); > + tracehook_notify_resume(NULL); > + vcpu->srcu_idx = srcu_read_lock(&kvm->srcu); > + } > + > + /* Any extra architecture specific work */ > + return arch_exit_to_guestmode_work(kvm, vcpu, ti_work); > +}
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