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    Subject[PATCH 4.19 047/191] xen/events: use a common cpu hotplug hook for event channels
    Date
    From: Juergen Gross <jgross@suse.com>

    commit 7beb290caa2adb0a399e735a1e175db9aae0523a upstream.

    Today only fifo event channels have a cpu hotplug callback. In order
    to prepare for more percpu (de)init work move that callback into
    events_base.c and add percpu_init() and percpu_deinit() hooks to
    struct evtchn_ops.

    This is part of XSA-332.

    Cc: stable@vger.kernel.org
    Signed-off-by: Juergen Gross <jgross@suse.com>
    Reviewed-by: Jan Beulich <jbeulich@suse.com>
    Reviewed-by: Wei Liu <wl@xen.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/xen/events/events_base.c | 25 +++++++++++++++++++++
    drivers/xen/events/events_fifo.c | 40 ++++++++++++++++-------------------
    drivers/xen/events/events_internal.h | 3 ++
    3 files changed, 47 insertions(+), 21 deletions(-)

    --- a/drivers/xen/events/events_base.c
    +++ b/drivers/xen/events/events_base.c
    @@ -33,6 +33,7 @@
    #include <linux/irqnr.h>
    #include <linux/pci.h>
    #include <linux/spinlock.h>
    +#include <linux/cpuhotplug.h>

    #ifdef CONFIG_X86
    #include <asm/desc.h>
    @@ -1833,6 +1834,26 @@ void xen_callback_vector(void) {}
    static bool fifo_events = true;
    module_param(fifo_events, bool, 0);

    +static int xen_evtchn_cpu_prepare(unsigned int cpu)
    +{
    + int ret = 0;
    +
    + if (evtchn_ops->percpu_init)
    + ret = evtchn_ops->percpu_init(cpu);
    +
    + return ret;
    +}
    +
    +static int xen_evtchn_cpu_dead(unsigned int cpu)
    +{
    + int ret = 0;
    +
    + if (evtchn_ops->percpu_deinit)
    + ret = evtchn_ops->percpu_deinit(cpu);
    +
    + return ret;
    +}
    +
    void __init xen_init_IRQ(void)
    {
    int ret = -EINVAL;
    @@ -1843,6 +1864,10 @@ void __init xen_init_IRQ(void)
    if (ret < 0)
    xen_evtchn_2l_init();

    + cpuhp_setup_state_nocalls(CPUHP_XEN_EVTCHN_PREPARE,
    + "xen/evtchn:prepare",
    + xen_evtchn_cpu_prepare, xen_evtchn_cpu_dead);
    +
    evtchn_to_irq = kcalloc(EVTCHN_ROW(xen_evtchn_max_channels()),
    sizeof(*evtchn_to_irq), GFP_KERNEL);
    BUG_ON(!evtchn_to_irq);
    --- a/drivers/xen/events/events_fifo.c
    +++ b/drivers/xen/events/events_fifo.c
    @@ -385,21 +385,6 @@ static void evtchn_fifo_resume(void)
    event_array_pages = 0;
    }

    -static const struct evtchn_ops evtchn_ops_fifo = {
    - .max_channels = evtchn_fifo_max_channels,
    - .nr_channels = evtchn_fifo_nr_channels,
    - .setup = evtchn_fifo_setup,
    - .bind_to_cpu = evtchn_fifo_bind_to_cpu,
    - .clear_pending = evtchn_fifo_clear_pending,
    - .set_pending = evtchn_fifo_set_pending,
    - .is_pending = evtchn_fifo_is_pending,
    - .test_and_set_mask = evtchn_fifo_test_and_set_mask,
    - .mask = evtchn_fifo_mask,
    - .unmask = evtchn_fifo_unmask,
    - .handle_events = evtchn_fifo_handle_events,
    - .resume = evtchn_fifo_resume,
    -};
    -
    static int evtchn_fifo_alloc_control_block(unsigned cpu)
    {
    void *control_block = NULL;
    @@ -422,19 +407,36 @@ static int evtchn_fifo_alloc_control_blo
    return ret;
    }

    -static int xen_evtchn_cpu_prepare(unsigned int cpu)
    +static int evtchn_fifo_percpu_init(unsigned int cpu)
    {
    if (!per_cpu(cpu_control_block, cpu))
    return evtchn_fifo_alloc_control_block(cpu);
    return 0;
    }

    -static int xen_evtchn_cpu_dead(unsigned int cpu)
    +static int evtchn_fifo_percpu_deinit(unsigned int cpu)
    {
    __evtchn_fifo_handle_events(cpu, true);
    return 0;
    }

    +static const struct evtchn_ops evtchn_ops_fifo = {
    + .max_channels = evtchn_fifo_max_channels,
    + .nr_channels = evtchn_fifo_nr_channels,
    + .setup = evtchn_fifo_setup,
    + .bind_to_cpu = evtchn_fifo_bind_to_cpu,
    + .clear_pending = evtchn_fifo_clear_pending,
    + .set_pending = evtchn_fifo_set_pending,
    + .is_pending = evtchn_fifo_is_pending,
    + .test_and_set_mask = evtchn_fifo_test_and_set_mask,
    + .mask = evtchn_fifo_mask,
    + .unmask = evtchn_fifo_unmask,
    + .handle_events = evtchn_fifo_handle_events,
    + .resume = evtchn_fifo_resume,
    + .percpu_init = evtchn_fifo_percpu_init,
    + .percpu_deinit = evtchn_fifo_percpu_deinit,
    +};
    +
    int __init xen_evtchn_fifo_init(void)
    {
    int cpu = smp_processor_id();
    @@ -448,9 +450,5 @@ int __init xen_evtchn_fifo_init(void)

    evtchn_ops = &evtchn_ops_fifo;

    - cpuhp_setup_state_nocalls(CPUHP_XEN_EVTCHN_PREPARE,
    - "xen/evtchn:prepare",
    - xen_evtchn_cpu_prepare, xen_evtchn_cpu_dead);
    -
    return ret;
    }
    --- a/drivers/xen/events/events_internal.h
    +++ b/drivers/xen/events/events_internal.h
    @@ -71,6 +71,9 @@ struct evtchn_ops {

    void (*handle_events)(unsigned cpu);
    void (*resume)(void);
    +
    + int (*percpu_init)(unsigned int cpu);
    + int (*percpu_deinit)(unsigned int cpu);
    };

    extern const struct evtchn_ops *evtchn_ops;

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