[Xen-devel] [PATCH v4] xen/arm: trap guest WFI

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

Trap guest WFI, block the guest VCPU unless it has pending interrupts.
Awake the guest vcpu when a new interrupt for it arrrives.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>

Changes in v4:
- local_events_need_delivery: check on the lr_pending list rather the
inflight list;
- local_events_need_delivery: no need to return true if
evtchn_upcall_pending is set and the VGIC_IRQ_EVTCHN_CALLBACK irq is
currently inflight: it just means that events are being handled.

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index e9c84c7..e2a072b 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -457,7 +457,7 @@ int construct_dom0(struct domain *d)
 
     v->arch.sctlr = SCTLR_BASE;
 
-    WRITE_SYSREG(HCR_PTW|HCR_BSU_OUTER|HCR_AMO|HCR_IMO|HCR_VM, HCR_EL2);
+    WRITE_SYSREG(HCR_PTW|HCR_BSU_OUTER|HCR_AMO|HCR_IMO|HCR_VM|HCR_TWI, 
HCR_EL2);
     isb();
 
     local_abort_enable();
diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index 600113c..0612f85 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -29,6 +29,7 @@
 #include <xen/hypercall.h>
 #include <xen/softirq.h>
 #include <xen/domain_page.h>
+#include <public/sched.h>
 #include <public/xen.h>
 #include <asm/regs.h>
 #include <asm/cpregs.h>
@@ -920,6 +921,11 @@ asmlinkage void do_trap_hypervisor(struct cpu_user_regs 
*regs)
     union hsr hsr = { .bits = READ_SYSREG32(ESR_EL2) };
 
     switch (hsr.ec) {
+    /* at the moment we only trap WFI */
+    case HSR_EC_WFI_WFE:
+        do_sched_op_compat(SCHEDOP_block, 0);
+        regs->pc += hsr.len ? 4 : 2;
+        break;
     case HSR_EC_CP15_32:
         if ( ! is_pv32_domain(current->domain) )
             goto bad_trap;
diff --git a/xen/arch/arm/vgic.c b/xen/arch/arm/vgic.c
index 0d24df0..8efcefc 100644
--- a/xen/arch/arm/vgic.c
+++ b/xen/arch/arm/vgic.c
@@ -608,12 +608,14 @@ void vgic_vcpu_inject_irq(struct vcpu *v, unsigned int 
irq, int virtual)
         {
             list_add_tail(&n->inflight, &iter->inflight);
             spin_unlock_irqrestore(&v->arch.vgic.lock, flags);
-            return;
+            goto out;
         }
     }
     list_add_tail(&n->inflight, &v->arch.vgic.inflight_irqs);
     spin_unlock_irqrestore(&v->arch.vgic.lock, flags);
     /* we have a new higher priority irq, inject it into the guest */
+out:
+    vcpu_unblock(v);
 }
 
 /*
diff --git a/xen/include/asm-arm/event.h b/xen/include/asm-arm/event.h
index 10f58af..cbcaba8 100644
--- a/xen/include/asm-arm/event.h
+++ b/xen/include/asm-arm/event.h
@@ -1,15 +1,18 @@
 #ifndef __ASM_EVENT_H__
 #define __ASM_EVENT_H__
 
+#include <asm/gic.h>
+#include <asm/domain.h>
+
 void vcpu_kick(struct vcpu *v);
 void vcpu_mark_events_pending(struct vcpu *v);
 
 static inline int local_events_need_delivery(void)
 {
-    /* TODO
-     * return (vcpu_info(v, evtchn_upcall_pending) &&
-                        !vcpu_info(v, evtchn_upcall_mask)); */
-        return 0;
+    struct pending_irq *p = irq_to_pending(current, VGIC_IRQ_EVTCHN_CALLBACK);
+    return ( !list_empty(&current->arch.vgic.lr_pending) ||
+            (vcpu_info(current, evtchn_upcall_pending) &&
+             list_empty(&p->inflight)));
 }
 
 int local_event_delivery_is_enabled(void);

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