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    SubjectRe: [PATCH] KVM: allow host header to be included even for !CONFIG_KVM
    On Thu, May 16, 2013 at 12:52:03AM +0200, Frederic Weisbecker wrote:
    > On Mon, Mar 25, 2013 at 02:14:20PM -0700, Kevin Hilman wrote:
    > > Gleb Natapov <gleb@redhat.com> writes:
    > >
    > > > On Sun, Mar 24, 2013 at 02:44:26PM +0100, Frederic Weisbecker wrote:
    > > >> 2013/3/21 Gleb Natapov <gleb@redhat.com>:
    > > >> > Isn't is simpler for kernel/context_tracking.c to define empty
    > > >> > __guest_enter()/__guest_exit() if !CONFIG_KVM.
    > > >>
    > > >> That doesn't look right. Off-cases are usually handled from the
    > > >> headers, right? So that we avoid iffdeffery ugliness in core code.
    > > > Lets put it in linux/context_tracking.h header then.
    > >
    > > Here's a version to do that.
    > >
    > > Kevin
    > >
    > > From d9d909394479dd7ff90b7bddb95a564945406719 Mon Sep 17 00:00:00 2001
    > > From: Kevin Hilman <khilman@linaro.org>
    > > Date: Mon, 25 Mar 2013 14:12:41 -0700
    > > Subject: [PATCH v2] ontext_tracking: fix !CONFIG_KVM compile: add stub guest
    > > enter/exit
    >
    > Sorry for my very delayed response...
    >
    > >
    > > When KVM is not enabled, or not available on a platform, the KVM
    > > headers should not be included. Instead, just define stub
    > > __guest_[enter|exit] functions.
    >
    > May be it would be cleaner to move guest_enter/exit definitions altogether
    > in linux/context_tracking.h
    >
    > After all that's where the implementation mostly belong to.
    >
    > Let me see if I can get that in shape.

    Does the following work for you?

    ---
    commit b1633c075527653a99df6fd54d2611cf8c8047f5
    Author: Frederic Weisbecker <fweisbec@gmail.com>
    Date: Thu May 16 01:21:38 2013 +0200

    kvm: Move guest entry/exit APIs to context_tracking

    Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

    diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
    index 365f4a6..fc09d7b 100644
    --- a/include/linux/context_tracking.h
    +++ b/include/linux/context_tracking.h
    @@ -3,6 +3,7 @@

    #include <linux/sched.h>
    #include <linux/percpu.h>
    +#include <linux/vtime.h>
    #include <asm/ptrace.h>

    struct context_tracking {
    @@ -19,6 +20,26 @@ struct context_tracking {
    } state;
    };

    +static inline void __guest_enter(void)
    +{
    + /*
    + * This is running in ioctl context so we can avoid
    + * the call to vtime_account() with its unnecessary idle check.
    + */
    + vtime_account_system(current);
    + current->flags |= PF_VCPU;
    +}
    +
    +static inline void __guest_exit(void)
    +{
    + /*
    + * This is running in ioctl context so we can avoid
    + * the call to vtime_account() with its unnecessary idle check.
    + */
    + vtime_account_system(current);
    + current->flags &= ~PF_VCPU;
    +}
    +
    #ifdef CONFIG_CONTEXT_TRACKING
    DECLARE_PER_CPU(struct context_tracking, context_tracking);

    @@ -35,6 +56,9 @@ static inline bool context_tracking_active(void)
    extern void user_enter(void);
    extern void user_exit(void);

    +extern void guest_enter(void);
    +extern void guest_exit(void);
    +
    static inline enum ctx_state exception_enter(void)
    {
    enum ctx_state prev_ctx;
    @@ -57,6 +81,17 @@ extern void context_tracking_task_switch(struct task_struct *prev,
    static inline bool context_tracking_in_user(void) { return false; }
    static inline void user_enter(void) { }
    static inline void user_exit(void) { }
    +
    +static inline void guest_enter(void)
    +{
    + __guest_enter();
    +}
    +
    +static inline void guest_exit(void)
    +{
    + __guest_exit();
    +}
    +
    static inline enum ctx_state exception_enter(void) { return 0; }
    static inline void exception_exit(enum ctx_state prev_ctx) { }
    static inline void context_tracking_task_switch(struct task_struct *prev,
    diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
    index f0eea07..8db53cf 100644
    --- a/include/linux/kvm_host.h
    +++ b/include/linux/kvm_host.h
    @@ -23,6 +23,7 @@
    #include <linux/ratelimit.h>
    #include <linux/err.h>
    #include <linux/irqflags.h>
    +#include <linux/context_tracking.h>
    #include <asm/signal.h>

    #include <linux/kvm.h>
    @@ -760,42 +761,6 @@ static inline int kvm_iommu_unmap_guest(struct kvm *kvm)
    }
    #endif

    -static inline void __guest_enter(void)
    -{
    - /*
    - * This is running in ioctl context so we can avoid
    - * the call to vtime_account() with its unnecessary idle check.
    - */
    - vtime_account_system(current);
    - current->flags |= PF_VCPU;
    -}
    -
    -static inline void __guest_exit(void)
    -{
    - /*
    - * This is running in ioctl context so we can avoid
    - * the call to vtime_account() with its unnecessary idle check.
    - */
    - vtime_account_system(current);
    - current->flags &= ~PF_VCPU;
    -}
    -
    -#ifdef CONFIG_CONTEXT_TRACKING
    -extern void guest_enter(void);
    -extern void guest_exit(void);
    -
    -#else /* !CONFIG_CONTEXT_TRACKING */
    -static inline void guest_enter(void)
    -{
    - __guest_enter();
    -}
    -
    -static inline void guest_exit(void)
    -{
    - __guest_exit();
    -}
    -#endif /* !CONFIG_CONTEXT_TRACKING */
    -
    static inline void kvm_guest_enter(void)
    {
    unsigned long flags;

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