linux-kernel - Re: [RFC patch 14/15] workpending: Provide infrastructure for work before entering a guest

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Date:   Fri, 20 Sep 2019 13:48:05 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Paolo Bonzini <pbonzini@...hat.com>
cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Marc Zyngier <maz@...nel.org>, kvm@...r.kernel.org,
        linux-arch@...r.kernel.org
Subject: Re: [RFC patch 14/15] workpending: Provide infrastructure for work
 before entering a guest

On Thu, 19 Sep 2019, Paolo Bonzini wrote:
> > +	/* Any extra architecture specific work */
> > +	return arch_exit_to_guestmode_work(kvm, vcpu, ti_work);
> > +}
> 
> Perhaps, in virt/kvm/kvm_main.c:
> 
> int kvm_exit_to_guestmode_work(struct kvm *kvm, struct kvm_vcpu *vcpu,
> 				unsigned long ti_work)
> {
...
> }
> 
> and in kernel/entry/common.c:
> 
> int core_exit_to_guestmode_work(unsigned long ti_work)
> {
...
> }

Makes sense.
 
> so that kernel/entry/ is not polluted with KVM structs and APIs.
> 
> Perhaps even extract the body of core_exit_to_usermode_work's while loop
> to a separate function, and call it as
> 
> 	core_exit_to_usermode_work_once(NULL,
> 				ti_work & EXIT_TO_GUESTMODE_WORK);

Doh, its too obvious now that you mention it :)

> from core_exit_to_guestmode_work.
> 
> In general I don't mind having these exit_to_guestmode functions in
> kvm_host.h, and only having entry-common.h export EXIT_TO_GUESTMODE_WORK
> and ARCH_EXIT_TO_GUESTMODE_WORK.  Unless you had good reasons to do the
> opposite...

That was an arbitrary choice and it does not matter much where it lives.

Thanks,

	tglx