[Xen-devel] [PATCH 15/24] xen/arm: receive Xen events on ARM

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

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@xxxxxxxxxxxxx>
---
 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;
+}
+
+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);
 
 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
        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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