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Message-ID: <20120801144418.GM7227@phenom.dumpdata.com>
Date: Wed, 1 Aug 2012 10:44:18 -0400
From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To: Stefano Stabellini <stefano.stabellini@...citrix.com>
Cc: linux-kernel@...r.kernel.org, xen-devel@...ts.xensource.com,
Ian.Campbell@...rix.com, tim@....org,
linux-arm-kernel@...ts.infradead.org, linaro-dev@...ts.linaro.org,
catalin.marinas@....com, arnd@...db.de
Subject: Re: [PATCH 15/24] xen/arm: receive Xen events on ARM
On Thu, Jul 26, 2012 at 04:33:57PM +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").
>
> On ARM Linux irqs are not enabled by default:
>
> - call enable_percpu_irq for xen_events_irq (drivers are supposed
> to call enable_irq after request_irq);
>
> - reset the IRQ_NOAUTOEN and IRQ_NOREQUEST flags that are enabled by
> default on ARM. If IRQ_NOAUTOEN is set, __setup_irq doesn't call
> irq_startup, that is responsible for calling irq_unmask at startup time.
> As a result event channels remain masked.
>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@...citrix.com>
> ---
> 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 | 18 +++++++++++++++---
> include/xen/events.h | 2 ++
> 6 files changed, 52 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
> index 854af1e..60d6d36 100644
> --- a/arch/arm/xen/enlighten.c
> +++ b/arch/arm/xen/enlighten.c
> @@ -7,8 +7,11 @@
> #include <xen/grant_table.h>
> #include <xen/hvm.h>
> #include <xen/xenbus.h>
> +#include <xen/events.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;
> +
> int xen_remap_domain_mfn_range(struct vm_area_struct *vma,
> unsigned long addr,
> unsigned long mfn, int nr,
> @@ -65,6 +70,9 @@ int __init xen_guest_init(void)
> if (of_address_to_resource(node, 0, &res))
> return -EINVAL;
> 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();
> @@ -114,3 +122,28 @@ int __init xen_guest_init(void)
> }
> EXPORT_SYMBOL_GPL(xen_guest_init);
> core_initcall(xen_guest_init);
> +
> +static irqreturn_t xen_arm_callback(int irq, void *arg)
> +{
> + xen_hvm_evtchn_do_upcall();
> + return 0;
Um, 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)) {
> + pr_err("Error requesting IRQ %d\n", xen_events_irq);
> + return -EINVAL;
> + }
> +
> + enable_percpu_irq(xen_events_irq, 0);
> +
> + return 0;
> +}
> +postcore_initcall(xen_init_events);
> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> index 6131d43..5a30502 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 7da65d3..9b506b2 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
> @@ -834,6 +839,7 @@ int bind_evtchn_to_irq(unsigned int evtchn)
> struct irq_info *info = info_for_irq(irq);
> WARN_ON(info == NULL || info->type != IRQT_EVTCHN);
> }
> + irq_clear_status_flags(irq, IRQ_NOREQUEST|IRQ_NOAUTOEN);
I feel that this should be its own commit by itself. I am not certain
of the implication of this on x86 and I think it deserves some explanation.
>
> out:
> mutex_unlock(&irq_mapping_update_lock);
> @@ -1377,7 +1383,9 @@ void xen_evtchn_do_upcall(struct pt_regs *regs)
> {
> struct pt_regs *old_regs = set_irq_regs(regs);
>
> +#ifdef CONFIG_X86
> exit_idle();
> +#endif
Doesn't exist? Or is that it does not need it?
> irq_enter();
>
> __xen_evtchn_do_upcall();
> @@ -1786,9 +1794,9 @@ 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);
> @@ -1804,6 +1812,7 @@ 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();
> @@ -1811,6 +1820,7 @@ 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());
> @@ -1826,4 +1836,6 @@ 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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