[Xen-devel] [PATCH v4 10/27] ARM: GICv3: forward pending LPIs to guests

[Andre Przywara <andre.przywara@xxxxxxx>]

Upon receiving an LPI, we need to find the right VCPU and virtual IRQ
number to get this IRQ injected.
Iterate our two-level LPI table to find this information quickly when
the host takes an LPI. Call the existing injection function to let the
GIC emulation deal with this interrupt.

Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
---
 xen/arch/arm/gic-v3-lpi.c  | 42 ++++++++++++++++++++++++++++++++++++++++++
 xen/arch/arm/gic.c         |  8 +++++++-
 xen/arch/arm/vgic-v3.c     | 11 +++++++++++
 xen/arch/arm/vgic.c        |  9 ++++++++-
 xen/include/asm-arm/irq.h  |  2 ++
 xen/include/asm-arm/vgic.h |  2 ++
 6 files changed, 72 insertions(+), 2 deletions(-)

diff --git a/xen/arch/arm/gic-v3-lpi.c b/xen/arch/arm/gic-v3-lpi.c
index d3ee141..ad89863 100644
--- a/xen/arch/arm/gic-v3-lpi.c
+++ b/xen/arch/arm/gic-v3-lpi.c
@@ -125,6 +125,48 @@ uint64_t gicv3_get_redist_address(unsigned int cpu, bool 
use_pta)
         return per_cpu(lpi_redist, cpu).redist_id << 16;
 }
 
+/*
+ * Handle incoming LPIs, which are a bit special, because they are potentially
+ * numerous and also only get injected into guests. Treat them specially here,
+ * by just looking up their target vCPU and virtual LPI number and hand it
+ * over to the injection function.
+ */
+void do_LPI(unsigned int lpi)
+{
+    struct domain *d;
+    union host_lpi *hlpip, hlpi;
+    struct vcpu *vcpu;
+
+    WRITE_SYSREG32(lpi, ICC_EOIR1_EL1);
+
+    hlpip = gic_get_host_lpi(lpi);
+    if ( !hlpip )
+        return;
+
+    hlpi.data = read_u64_atomic(&hlpip->data);
+
+    /* Unmapped events are marked with an invalid LPI ID. */
+    if ( hlpi.virt_lpi == INVALID_LPI )
+        return;
+
+    d = rcu_lock_domain_by_id(hlpi.dom_id);
+    if ( !d )
+        return;
+
+    /* Make sure we don't step beyond the vcpu array. */
+    if ( hlpi.vcpu_id >= d->max_vcpus )
+    {
+        rcu_unlock_domain(d);
+        return;
+    }
+
+    vcpu = d->vcpu[hlpi.vcpu_id];
+
+    vgic_vcpu_inject_irq(vcpu, hlpi.virt_lpi);
+
+    rcu_unlock_domain(d);
+}
+
 static int gicv3_lpi_allocate_pendtable(uint64_t *reg)
 {
     uint64_t val;
diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
index 3ed6f81..a6037d4 100644
--- a/xen/arch/arm/gic.c
+++ b/xen/arch/arm/gic.c
@@ -709,7 +709,13 @@ void gic_interrupt(struct cpu_user_regs *regs, int is_fiq)
             do_IRQ(regs, irq, is_fiq);
             local_irq_disable();
         }
-        else if (unlikely(irq < 16))
+#ifdef CONFIG_HAS_ITS
+        else if ( is_lpi(irq) )
+        {
+            do_LPI(irq);
+        }
+#endif
+        else if ( unlikely(irq < 16) )
         {
             do_sgi(regs, irq);
         }
diff --git a/xen/arch/arm/vgic-v3.c b/xen/arch/arm/vgic-v3.c
index 95fa0ba..797fd86 100644
--- a/xen/arch/arm/vgic-v3.c
+++ b/xen/arch/arm/vgic-v3.c
@@ -347,6 +347,17 @@ struct pending_irq *lpi_to_pending(struct domain *d, 
unsigned int lpi)
     return pirq;
 }
 
+/* Retrieve the priority of an LPI from its struct pending_irq. */
+int vgic_lpi_get_priority(struct domain *d, uint32_t vlpi)
+{
+    struct pending_irq *p = lpi_to_pending(d, vlpi);
+
+    if ( !p )
+        return GIC_PRI_IRQ;
+
+    return p->lpi_priority;
+}
+
 static int __vgic_v3_rdistr_rd_mmio_write(struct vcpu *v, mmio_info_t *info,
                                           uint32_t gicr_reg,
                                           register_t r)
diff --git a/xen/arch/arm/vgic.c b/xen/arch/arm/vgic.c
index 28f6f66..4720f46 100644
--- a/xen/arch/arm/vgic.c
+++ b/xen/arch/arm/vgic.c
@@ -226,10 +226,17 @@ struct vcpu *vgic_get_target_vcpu(struct vcpu *v, 
unsigned int virq)
 
 static int vgic_get_virq_priority(struct vcpu *v, unsigned int virq)
 {
-    struct vgic_irq_rank *rank = vgic_rank_irq(v, virq);
+    struct vgic_irq_rank *rank;
     unsigned long flags;
     int priority;
 
+#ifdef CONFIG_HAS_ITS
+    /* LPIs don't have a rank, also store their priority separately. */
+    if ( is_lpi(virq) )
+        return vgic_lpi_get_priority(v->domain, virq);
+#endif
+
+    rank = vgic_rank_irq(v, virq);
     vgic_lock_rank(v, rank, flags);
     priority = rank->priority[virq & INTERRUPT_RANK_MASK];
     vgic_unlock_rank(v, rank, flags);
diff --git a/xen/include/asm-arm/irq.h b/xen/include/asm-arm/irq.h
index 2f7ee8a..0cd0117 100644
--- a/xen/include/asm-arm/irq.h
+++ b/xen/include/asm-arm/irq.h
@@ -46,6 +46,8 @@ static inline bool is_lpi(unsigned int irq)
     return irq >= LPI_OFFSET;
 }
 
+void do_LPI(unsigned int irq);
+
 #define domain_pirq_to_irq(d, pirq) (pirq)
 
 bool_t is_assignable_irq(unsigned int irq);
diff --git a/xen/include/asm-arm/vgic.h b/xen/include/asm-arm/vgic.h
index 69ef160..a24a971 100644
--- a/xen/include/asm-arm/vgic.h
+++ b/xen/include/asm-arm/vgic.h
@@ -66,12 +66,14 @@ struct pending_irq
 #define GIC_IRQ_GUEST_VISIBLE  2
 #define GIC_IRQ_GUEST_ENABLED  3
 #define GIC_IRQ_GUEST_MIGRATING   4
+#define GIC_IRQ_GUEST_LPI_PENDING 5
     unsigned long status;
     struct irq_desc *desc; /* only set it the irq corresponds to a physical 
irq */
     unsigned int irq;
 #define GIC_INVALID_LR         (uint8_t)~0
     uint8_t lr;
     uint8_t priority;
+    uint8_t lpi_priority;       /* Caches the priority if this is an LPI. */
     /* inflight is used to append instances of pending_irq to
      * vgic.inflight_irqs */
     struct list_head inflight;
-- 
2.9.0


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