[Xen-devel] [PATCH v5 3/7] xen/arm: SMP support

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

Map vcpu_info using VCPUOP_register_vcpu_info on all the online vcpus,
make sure the allocated struct doesn't cross a page boundary.

Call enable_percpu_irq on every cpu.

Changes in v5:
- allocate xen_vcpu_info dynamically, aligning it to the size of the
struct;
- use VCPUOP_register_vcpu_info on cpu0 too.

Changed in v2:
- move the percpu variable argument fix to a separate patch;
- remove unused variable.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
---
 arch/arm/xen/enlighten.c |   48 ++++++++++++++++++++++++++++++++++++++++-----
 1 files changed, 42 insertions(+), 6 deletions(-)

diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
index 82d5e63..6c87d11 100644
--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c
@@ -2,6 +2,7 @@
 #include <xen/events.h>
 #include <xen/grant_table.h>
 #include <xen/hvm.h>
+#include <xen/interface/vcpu.h>
 #include <xen/interface/xen.h>
 #include <xen/interface/memory.h>
 #include <xen/interface/hvm/params.h>
@@ -32,6 +33,7 @@ struct shared_info xen_dummy_shared_info;
 struct shared_info *HYPERVISOR_shared_info = (void *)&xen_dummy_shared_info;
 
 DEFINE_PER_CPU(struct vcpu_info *, xen_vcpu);
+static struct vcpu_info __percpu *xen_vcpu_info;
 
 /* These are unused until we support booting "pre-ballooned" */
 unsigned long xen_released_pages;
@@ -148,6 +150,29 @@ int xen_unmap_domain_mfn_range(struct vm_area_struct *vma,
 }
 EXPORT_SYMBOL_GPL(xen_unmap_domain_mfn_range);
 
+static int __init xen_secondary_init(unsigned int cpu)
+{
+       struct vcpu_register_vcpu_info info;
+       struct vcpu_info *vcpup;
+       int err;
+
+       pr_info("Xen: initializing cpu%d\n", cpu);
+       vcpup = per_cpu_ptr(xen_vcpu_info, cpu);
+
+       info.mfn = __pa(vcpup) >> PAGE_SHIFT;
+       info.offset = offset_in_page(vcpup);
+
+       err = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info, cpu, &info);
+       if (err) {
+               pr_debug("register_vcpu_info failed: err=%d\n", err);
+       } else {
+               /* This cpu is using the registered vcpu info, even if
+                  later ones fail to. */
+               per_cpu(xen_vcpu, cpu) = vcpup;
+       }
+       return 0;
+}
+
 /*
  * see Documentation/devicetree/bindings/arm/xen.txt for the
  * documentation of the Xen Device Tree format.
@@ -163,6 +188,7 @@ static int __init xen_guest_init(void)
        const char *version = NULL;
        const char *xen_prefix = "xen,xen-";
        struct resource res;
+       int i;
 
        node = of_find_compatible_node(NULL, NULL, "xen,xen");
        if (!node) {
@@ -209,13 +235,18 @@ static int __init xen_guest_init(void)
 
        /* xen_vcpu is a pointer to the vcpu_info struct in the shared_info
         * page, we use it in the event channel upcall and in some pvclock
-        * related functions. We don't need the vcpu_info placement
-        * optimizations because we don't use any pv_mmu or pv_irq op on
-        * HVM.
+        * related functions. 
         * The shared info contains exactly 1 CPU (the boot CPU). The guest
         * is required to use VCPUOP_register_vcpu_info to place vcpu info
-        * for secondary CPUs as they are brought up. */
-       per_cpu(xen_vcpu, 0) = &HYPERVISOR_shared_info->vcpu_info[0];
+        * for secondary CPUs as they are brought up.
+        * For uniformity we use VCPUOP_register_vcpu_info even on cpu0.
+        */
+       xen_vcpu_info = __alloc_percpu(sizeof(struct vcpu_info),
+                                              sizeof(struct vcpu_info));
+       if (xen_vcpu_info == NULL)
+               return -ENOMEM;
+       for_each_online_cpu(i)
+               xen_secondary_init(i);
 
        gnttab_init();
        if (!xen_initial_domain())
@@ -231,6 +262,11 @@ static irqreturn_t xen_arm_callback(int irq, void *arg)
        return IRQ_HANDLED;
 }
 
+static __init void xen_percpu_enable_events(void *unused)
+{
+       enable_percpu_irq(xen_events_irq, 0);
+}
+
 static int __init xen_init_events(void)
 {
        if (!xen_domain() || xen_events_irq < 0)
@@ -244,7 +280,7 @@ static int __init xen_init_events(void)
                return -EINVAL;
        }
 
-       enable_percpu_irq(xen_events_irq, 0);
+       on_each_cpu(xen_percpu_enable_events, NULL, 0);
 
        return 0;
 }
-- 
1.7.2.5


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