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    Subject[PATCH v3 3/4] xen: Mark "xen_nopvspin" parameter obsolete and map it to "nopvspin"
    Date
    Fix stale description of "xen_nopvspin" as we use qspinlock now.

    Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
    Reviewed-by: Juergen Gross <jgross@suse.com>
    Cc: Jonathan Corbet <corbet@lwn.net>
    Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
    Cc: Juergen Gross <jgross@suse.com>
    Cc: Stefano Stabellini <sstabellini@kernel.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: "H. Peter Anvin" <hpa@zytor.com>
    ---
    Documentation/admin-guide/kernel-parameters.txt | 7 ++++---
    arch/x86/xen/spinlock.c | 13 +++++++------
    2 files changed, 11 insertions(+), 9 deletions(-)

    diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
    index 4b956d8..1f0a62f 100644
    --- a/Documentation/admin-guide/kernel-parameters.txt
    +++ b/Documentation/admin-guide/kernel-parameters.txt
    @@ -5303,8 +5303,9 @@
    never -- do not unplug even if version check succeeds

    xen_nopvspin [X86,XEN]
    - Disables the ticketlock slowpath using Xen PV
    - optimizations.
    + Disables the qspinlock slowpath using Xen PV optimizations.
    + This parameter is obsoleted by "nopvspin" parameter, which
    + has equivalent effect for XEN platform.

    xen_nopv [X86]
    Disables the PV optimizations forcing the HVM guest to
    @@ -5330,7 +5331,7 @@
    as generic guest with no PV drivers. Currently support
    XEN HVM, KVM, HYPER_V and VMWARE guest.

    - nopvspin [X86,KVM] Disables the qspinlock slow path
    + nopvspin [X86,XEN,KVM] Disables the qspinlock slow path
    using PV optimizations which allow the hypervisor to
    'idle' the guest on lock contention.

    diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c
    index 6deb490..092a53f 100644
    --- a/arch/x86/xen/spinlock.c
    +++ b/arch/x86/xen/spinlock.c
    @@ -18,7 +18,6 @@
    static DEFINE_PER_CPU(int, lock_kicker_irq) = -1;
    static DEFINE_PER_CPU(char *, irq_name);
    static DEFINE_PER_CPU(atomic_t, xen_qlock_wait_nest);
    -static bool xen_pvspin = true;

    static void xen_qlock_kick(int cpu)
    {
    @@ -68,7 +67,7 @@ void xen_init_lock_cpu(int cpu)
    int irq;
    char *name;

    - if (!xen_pvspin)
    + if (!pvspin)
    return;

    WARN(per_cpu(lock_kicker_irq, cpu) >= 0, "spinlock on CPU%d exists on IRQ%d!\n",
    @@ -93,7 +92,7 @@ void xen_init_lock_cpu(int cpu)

    void xen_uninit_lock_cpu(int cpu)
    {
    - if (!xen_pvspin)
    + if (!pvspin)
    return;

    unbind_from_irqhandler(per_cpu(lock_kicker_irq, cpu), NULL);
    @@ -117,9 +116,9 @@ void __init xen_init_spinlocks(void)

    /* Don't need to use pvqspinlock code if there is only 1 vCPU. */
    if (num_possible_cpus() == 1)
    - xen_pvspin = false;
    + pvspin = false;

    - if (!xen_pvspin) {
    + if (!pvspin) {
    printk(KERN_DEBUG "xen: PV spinlocks disabled\n");
    static_branch_disable(&virt_spin_lock_key);
    return;
    @@ -137,7 +136,9 @@ void __init xen_init_spinlocks(void)

    static __init int xen_parse_nopvspin(char *arg)
    {
    - xen_pvspin = false;
    + pr_notice("\"xen_nopvspin\" is deprecated, please use \"nopvspin\" instead\n");
    + if (xen_domain())
    + pvspin = false;
    return 0;
    }
    early_param("xen_nopvspin", xen_parse_nopvspin);
    --
    1.8.3.1
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