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    SubjectRe: [PATCH v2 15/23] xen/arm: receive Xen events on ARM
    On Mon, Aug 06, 2012 at 03:27:18PM +0100, Stefano Stabellini wrote:
    > Compile events.c on ARM.
    > Parse, map and enable the IRQ to get event notifications from the device
    > tree (node "/xen").
    >
    > Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
    > ---
    > arch/arm/include/asm/xen/events.h | 18 ++++++++++++++++++
    > arch/arm/xen/enlighten.c | 33 +++++++++++++++++++++++++++++++++
    > arch/x86/xen/enlighten.c | 1 +
    > arch/x86/xen/irq.c | 1 +
    > arch/x86/xen/xen-ops.h | 1 -
    > drivers/xen/events.c | 17 ++++++++++++++---
    > include/xen/events.h | 2 ++
    > 7 files changed, 69 insertions(+), 4 deletions(-)
    > create mode 100644 arch/arm/include/asm/xen/events.h
    >
    > diff --git a/arch/arm/include/asm/xen/events.h b/arch/arm/include/asm/xen/events.h
    > new file mode 100644
    > index 0000000..94b4e90
    > --- /dev/null
    > +++ b/arch/arm/include/asm/xen/events.h
    > @@ -0,0 +1,18 @@
    > +#ifndef _ASM_ARM_XEN_EVENTS_H
    > +#define _ASM_ARM_XEN_EVENTS_H
    > +
    > +#include <asm/ptrace.h>
    > +
    > +enum ipi_vector {
    > + XEN_PLACEHOLDER_VECTOR,
    > +
    > + /* Xen IPIs go here */
    > + XEN_NR_IPIS,
    > +};
    > +
    > +static inline int xen_irqs_disabled(struct pt_regs *regs)
    > +{
    > + return raw_irqs_disabled_flags(regs->ARM_cpsr);
    > +}
    > +
    > +#endif /* _ASM_ARM_XEN_EVENTS_H */
    > diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
    > index e5e92d5..87b17f0 100644
    > --- a/arch/arm/xen/enlighten.c
    > +++ b/arch/arm/xen/enlighten.c
    > @@ -1,4 +1,5 @@
    > #include <xen/xen.h>
    > +#include <xen/events.h>
    > #include <xen/grant_table.h>
    > #include <xen/hvm.h>
    > #include <xen/interface/xen.h>
    > @@ -9,6 +10,8 @@
    > #include <xen/xenbus.h>
    > #include <asm/xen/hypervisor.h>
    > #include <asm/xen/hypercall.h>
    > +#include <linux/interrupt.h>
    > +#include <linux/irqreturn.h>
    > #include <linux/module.h>
    > #include <linux/of.h>
    > #include <linux/of_irq.h>
    > @@ -33,6 +36,8 @@ EXPORT_SYMBOL_GPL(xen_have_vector_callback);
    > int xen_platform_pci_unplug = XEN_UNPLUG_ALL;
    > EXPORT_SYMBOL_GPL(xen_platform_pci_unplug);
    >
    > +static __read_mostly int xen_events_irq = -1;
    > +

    So this is global..
    > int xen_remap_domain_mfn_range(struct vm_area_struct *vma,
    > unsigned long addr,
    > unsigned long mfn, int nr,
    > @@ -66,6 +71,9 @@ static int __init xen_guest_init(void)
    > if (of_address_to_resource(node, GRANT_TABLE_PHYSADDR, &res))
    > return 0;
    > xen_hvm_resume_frames = res.start >> PAGE_SHIFT;
    > + xen_events_irq = irq_of_parse_and_map(node, 0);
    > + pr_info("Xen support found, events_irq=%d gnttab_frame_pfn=%lx\n",
    > + xen_events_irq, xen_hvm_resume_frames);
    > xen_domain_type = XEN_HVM_DOMAIN;
    >
    > xen_setup_features();
    > @@ -107,3 +115,28 @@ static int __init xen_guest_init(void)
    > return 0;
    > }
    > core_initcall(xen_guest_init);
    > +
    > +static irqreturn_t xen_arm_callback(int irq, void *arg)
    > +{
    > + xen_hvm_evtchn_do_upcall();
    > + return IRQ_HANDLED;
    > +}
    > +
    > +static int __init xen_init_events(void)
    > +{
    > + if (!xen_domain() || xen_events_irq < 0)
    > + return -ENODEV;
    > +
    > + xen_init_IRQ();
    > +
    > + if (request_percpu_irq(xen_events_irq, xen_arm_callback,
    > + "events", xen_vcpu)) {

    But here you are asking for it to be percpu? What if there are other
    interrupts on the _other_ CPUs that conflict with it?
    > + pr_err("Error requesting IRQ %d\n", xen_events_irq);
    > + return -EINVAL;
    > + }
    > +
    > + enable_percpu_irq(xen_events_irq, 0);

    Uh, that is bold. One global to rule them all, eh? Should you make
    it at least:
    static DEFINE_PER_CPU(int, xen_events_irq);
    ?

    > +
    > + return 0;
    > +}
    > +postcore_initcall(xen_init_events);
    > diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
    > index ff962d4..9f8b0ef 100644
    > --- a/arch/x86/xen/enlighten.c
    > +++ b/arch/x86/xen/enlighten.c
    > @@ -33,6 +33,7 @@
    > #include <linux/memblock.h>
    >
    > #include <xen/xen.h>
    > +#include <xen/events.h>
    > #include <xen/interface/xen.h>
    > #include <xen/interface/version.h>
    > #include <xen/interface/physdev.h>
    > diff --git a/arch/x86/xen/irq.c b/arch/x86/xen/irq.c
    > index 1573376..01a4dc0 100644
    > --- a/arch/x86/xen/irq.c
    > +++ b/arch/x86/xen/irq.c
    > @@ -5,6 +5,7 @@
    > #include <xen/interface/xen.h>
    > #include <xen/interface/sched.h>
    > #include <xen/interface/vcpu.h>
    > +#include <xen/events.h>
    >
    > #include <asm/xen/hypercall.h>
    > #include <asm/xen/hypervisor.h>
    > diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
    > index 202d4c1..2368295 100644
    > --- a/arch/x86/xen/xen-ops.h
    > +++ b/arch/x86/xen/xen-ops.h
    > @@ -35,7 +35,6 @@ void xen_set_pat(u64);
    >
    > char * __init xen_memory_setup(void);
    > void __init xen_arch_setup(void);
    > -void __init xen_init_IRQ(void);
    > void xen_enable_sysenter(void);
    > void xen_enable_syscall(void);
    > void xen_vcpu_restore(void);
    > diff --git a/drivers/xen/events.c b/drivers/xen/events.c
    > index 7595581..5ecb596 100644
    > --- a/drivers/xen/events.c
    > +++ b/drivers/xen/events.c
    > @@ -31,14 +31,16 @@
    > #include <linux/irqnr.h>
    > #include <linux/pci.h>
    >
    > +#ifdef CONFIG_X86
    > #include <asm/desc.h>
    > #include <asm/ptrace.h>
    > #include <asm/irq.h>
    > #include <asm/idle.h>
    > #include <asm/io_apic.h>
    > -#include <asm/sync_bitops.h>
    > #include <asm/xen/page.h>
    > #include <asm/xen/pci.h>
    > +#endif
    > +#include <asm/sync_bitops.h>
    > #include <asm/xen/hypercall.h>
    > #include <asm/xen/hypervisor.h>
    >
    > @@ -50,6 +52,9 @@
    > #include <xen/interface/event_channel.h>
    > #include <xen/interface/hvm/hvm_op.h>
    > #include <xen/interface/hvm/params.h>
    > +#include <xen/interface/physdev.h>
    > +#include <xen/interface/sched.h>
    > +#include <asm/hw_irq.h>
    >
    > /*
    > * This lock protects updates to the following mapping and reference-count
    > @@ -1374,7 +1379,9 @@ void xen_evtchn_do_upcall(struct pt_regs *regs)
    > {
    > struct pt_regs *old_regs = set_irq_regs(regs);
    >
    > +#ifdef CONFIG_X86

    Please explain this with a comment.

    > exit_idle();
    > +#endif
    > irq_enter();
    >
    > __xen_evtchn_do_upcall();
    > @@ -1783,9 +1790,9 @@ void xen_callback_vector(void)
    > void xen_callback_vector(void) {}
    > #endif
    >
    > -void __init xen_init_IRQ(void)
    > +void xen_init_IRQ(void)
    > {
    > - int i, rc;
    > + int i;
    >
    > evtchn_to_irq = kcalloc(NR_EVENT_CHANNELS, sizeof(*evtchn_to_irq),
    > GFP_KERNEL);
    > @@ -1801,6 +1808,7 @@ void __init xen_init_IRQ(void)
    >
    > pirq_needs_eoi = pirq_needs_eoi_flag;
    >
    > +#ifdef CONFIG_X86
    > if (xen_hvm_domain()) {
    > xen_callback_vector();
    > native_init_IRQ();
    > @@ -1808,6 +1816,7 @@ void __init xen_init_IRQ(void)
    > * __acpi_register_gsi can point at the right function */
    > pci_xen_hvm_init();
    > } else {
    > + int rc;
    > struct physdev_pirq_eoi_gmfn eoi_gmfn;
    >
    > irq_ctx_init(smp_processor_id());
    > @@ -1823,4 +1832,6 @@ void __init xen_init_IRQ(void)
    > } else
    > pirq_needs_eoi = pirq_check_eoi_map;
    > }
    > +#endif
    > }
    > +EXPORT_SYMBOL_GPL(xen_init_IRQ);
    > diff --git a/include/xen/events.h b/include/xen/events.h
    > index 04399b2..c6bfe01 100644
    > --- a/include/xen/events.h
    > +++ b/include/xen/events.h
    > @@ -109,4 +109,6 @@ int xen_irq_from_gsi(unsigned gsi);
    > /* Determine whether to ignore this IRQ if it is passed to a guest. */
    > int xen_test_irq_shared(int irq);
    >
    > +/* initialize Xen IRQ subsystem */
    > +void xen_init_IRQ(void);
    > #endif /* _XEN_EVENTS_H */
    > --
    > 1.7.2.5


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