Re: [PATCH v2 15/23] xen/arm: receive Xen events on ARM

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

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