[Xen-devel] [PATCH 3/5] xen/arm: Don't reinject the IRQ if it's already in LRs

[Julien Grall <julien.grall@xxxxxxxxxx>]

From: Julien Grall <julien.grall@xxxxxxxxxx>

When an IRQ, marked as IRQS_ONESHOT, is injected Linux will:
  - Disable the IRQ
  - Call the interrupt handler
  - Conditionnally enable the IRQ
  - EOI the IRQ

When Linux will re-enable the IRQ, Xen will inject again the IRQ because it's
still inflight. Therefore, LRs will contains duplicated IRQs and Xen will
EOI it twice if it's a physical IRQ.

Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
---
 xen/arch/arm/gic.c        |   27 +++++++++++++++++++++++++++
 xen/arch/arm/vgic.c       |    3 ++-
 xen/include/asm-arm/gic.h |    3 +++
 3 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
index 21575df..bf05716 100644
--- a/xen/arch/arm/gic.c
+++ b/xen/arch/arm/gic.c
@@ -570,6 +570,33 @@ int __init setup_dt_irq(const struct dt_irq *irq, struct 
irqaction *new)
     return rc;
 }
 
+/* Check if an IRQ was already injected to the current VCPU */
+bool_t gic_irq_injected(unsigned int irq)
+{
+    bool_t found = 0;
+    int i = 0;
+    unsigned int virq;
+
+    spin_lock_irq(&gic.lock);
+
+    while ( (i = find_next_bit((unsigned long *)&this_cpu(lr_mask),
+                               nr_lrs, i)) < nr_lrs )
+    {
+        virq = GICH[GICH_LR + i] & GICH_LR_VIRTUAL_MASK;
+
+        if ( virq == irq )
+        {
+            found = 1;
+            break;
+        }
+        i++;
+    }
+
+    spin_unlock_irq(&gic.lock);
+
+    return found;
+}
+
 static inline void gic_set_lr(int lr, unsigned int virtual_irq,
         unsigned int state, unsigned int priority)
 {
diff --git a/xen/arch/arm/vgic.c b/xen/arch/arm/vgic.c
index 2d91dce..cea9233 100644
--- a/xen/arch/arm/vgic.c
+++ b/xen/arch/arm/vgic.c
@@ -369,8 +369,9 @@ static void vgic_enable_irqs(struct vcpu *v, uint32_t r, 
int n)
     while ( (i = find_next_bit((const long unsigned int *) &r, 32, i)) < 32 ) {
         irq = i + (32 * n);
         p = irq_to_pending(v, irq);
-        if ( !list_empty(&p->inflight) )
+        if ( !list_empty(&p->inflight) && !gic_irq_injected(irq) )
             gic_set_guest_irq(v, irq, GICH_LR_PENDING, p->priority);
+
         i++;
     }
 }
diff --git a/xen/include/asm-arm/gic.h b/xen/include/asm-arm/gic.h
index 513c1fc..f9e9ef1 100644
--- a/xen/include/asm-arm/gic.h
+++ b/xen/include/asm-arm/gic.h
@@ -197,6 +197,9 @@ extern unsigned int gic_number_lines(void);
 int gic_irq_xlate(const u32 *intspec, unsigned int intsize,
                   unsigned int *out_hwirq, unsigned int *out_type);
 
+/* Check if an IRQ was already injected to the current VCPU */
+bool_t gic_irq_injected(unsigned int irq);
+
 #endif /* __ASSEMBLY__ */
 #endif
 
-- 
1.7.10.4


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