[PATCH 08/10] KVM: arm/arm64: vgic: Handle unshared mapped interrupts

[Eric Auger]

Virtual interrupts directly mapped to physical interrupts require
some special care. Their pending and active state must be observed
at distributor level and not in the list register.

Also a level sensitive interrupt's level is not toggled down by any
maintenance IRQ handler as the EOI is not trapped.

This patch adds an host_irq field in vgic_irq struct to easily
get the irqchip state of the host irq. We also handle the
physical IRQ case in vgic_validate_injection and add helpers to
get the line level and active state.

Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
---
 include/kvm/arm_vgic.h    |  4 +++-
 virt/kvm/arm/arch_timer.c |  3 ++-
 virt/kvm/arm/vgic/vgic.c  | 44 ++++++++++++++++++++++++++++++++++++++------
 virt/kvm/arm/vgic/vgic.h  |  9 ++++++++-
 4 files changed, 51 insertions(+), 9 deletions(-)

diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index ef71858..695ebc7 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -112,6 +112,7 @@ struct vgic_irq {
 	bool hw;			/* Tied to HW IRQ */
 	struct kref refcount;		/* Used for LPIs */
 	u32 hwintid;			/* HW INTID number */
+	unsigned int host_irq;		/* linux irq corresponding to hwintid */
 	union {
 		u8 targets;			/* GICv2 target VCPUs mask */
 		u32 mpidr;			/* GICv3 target VCPU */
@@ -301,7 +302,8 @@ int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
 			bool level);
 int kvm_vgic_inject_mapped_irq(struct kvm *kvm, int cpuid, unsigned int intid,
 			       bool level);
-int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, u32 virt_irq, u32 phys_irq);
+int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, unsigned int host_irq,
+			  u32 virt_irq, u32 phys_irq);
 int kvm_vgic_unmap_phys_irq(struct kvm_vcpu *vcpu, unsigned int virt_irq);
 bool kvm_vgic_map_is_active(struct kvm_vcpu *vcpu, unsigned int virt_irq);
 
diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
index 5976609..45f4779 100644
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -651,7 +651,8 @@ int kvm_timer_enable(struct kvm_vcpu *vcpu)
 	 * Tell the VGIC that the virtual interrupt is tied to a
 	 * physical interrupt. We do that once per VCPU.
 	 */
-	ret = kvm_vgic_map_phys_irq(vcpu, vtimer->irq.irq, phys_irq);
+	ret = kvm_vgic_map_phys_irq(vcpu, host_vtimer_irq,
+				    vtimer->irq.irq, phys_irq);
 	if (ret)
 		return ret;
 
diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index 83b24d2..aa0618c 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -137,6 +137,28 @@ void vgic_put_irq(struct kvm *kvm, struct vgic_irq *irq)
 	kfree(irq);
 }
 
+bool irq_line_level(struct vgic_irq *irq)
+{
+	bool line_level = irq->line_level;
+
+	if (unlikely(is_unshared_mapped(irq)))
+		WARN_ON(irq_get_irqchip_state(irq->host_irq,
+					      IRQCHIP_STATE_PENDING,
+					      &line_level));
+	return line_level;
+}
+
+bool irq_is_active(struct vgic_irq *irq)
+{
+	bool is_active = irq->active;
+
+	if (unlikely(is_unshared_mapped(irq)))
+		WARN_ON(irq_get_irqchip_state(irq->host_irq,
+					      IRQCHIP_STATE_ACTIVE,
+					      &is_active));
+	return is_active;
+}
+
 /**
  * kvm_vgic_target_oracle - compute the target vcpu for an irq
  *
@@ -153,7 +175,7 @@ static struct kvm_vcpu *vgic_target_oracle(struct vgic_irq *irq)
 	DEBUG_SPINLOCK_BUG_ON(!spin_is_locked(&irq->irq_lock));
 
 	/* If the interrupt is active, it must stay on the current vcpu */
-	if (irq->active)
+	if (irq_is_active(irq))
 		return irq->vcpu ? : irq->target_vcpu;
 
 	/*
@@ -195,14 +217,18 @@ static int vgic_irq_cmp(void *priv, struct list_head *a, struct list_head *b)
 {
 	struct vgic_irq *irqa = container_of(a, struct vgic_irq, ap_list);
 	struct vgic_irq *irqb = container_of(b, struct vgic_irq, ap_list);
+	bool activea, activeb;
 	bool penda, pendb;
 	int ret;
 
 	spin_lock(&irqa->irq_lock);
 	spin_lock_nested(&irqb->irq_lock, SINGLE_DEPTH_NESTING);
 
-	if (irqa->active || irqb->active) {
-		ret = (int)irqb->active - (int)irqa->active;
+	activea = irq_is_active(irqa);
+	activeb = irq_is_active(irqb);
+
+	if (activea || activeb) {
+		ret = (int)activeb - (int)activea;
 		goto out;
 	}
 
@@ -234,13 +260,17 @@ static void vgic_sort_ap_list(struct kvm_vcpu *vcpu)
 
 /*
  * Only valid injection if changing level for level-triggered IRQs or for a
- * rising edge.
+ * rising edge. Injection of virtual interrupts associated to physical
+ * interrupts always is valid.
  */
 static bool vgic_validate_injection(struct vgic_irq *irq, bool level)
 {
 	switch (irq->config) {
 	case VGIC_CONFIG_LEVEL:
-		return irq->line_level != level;
+		if (unlikely(is_unshared_mapped(irq)))
+			return true;
+		else
+			return irq->line_level != level;
 	case VGIC_CONFIG_EDGE:
 		return level;
 	}
@@ -392,7 +422,8 @@ int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
 	return 0;
 }
 
-int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, u32 virt_irq, u32 phys_irq)
+int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, unsigned int host_irq,
+			  u32 virt_irq, u32 phys_irq)
 {
 	struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, virt_irq);
 
@@ -402,6 +433,7 @@ int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, u32 virt_irq, u32 phys_irq)
 
 	irq->hw = true;
 	irq->hwintid = phys_irq;
+	irq->host_irq = host_irq;
 
 	spin_unlock(&irq->irq_lock);
 	vgic_put_irq(vcpu->kvm, irq);
diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
index da83e4c..dc4972b 100644
--- a/virt/kvm/arm/vgic/vgic.h
+++ b/virt/kvm/arm/vgic/vgic.h
@@ -17,6 +17,7 @@
 #define __KVM_ARM_VGIC_NEW_H__
 
 #include <linux/irqchip/arm-gic-common.h>
+#include <linux/interrupt.h>
 
 #define PRODUCT_ID_KVM		0x4b	/* ASCII code K */
 #define IMPLEMENTER_ARM		0x43b
@@ -96,14 +97,20 @@
 /* we only support 64 kB translation table page size */
 #define KVM_ITS_L1E_ADDR_MASK		GENMASK_ULL(51, 16)
 
+bool irq_line_level(struct vgic_irq *irq);
+bool irq_is_active(struct vgic_irq *irq);
+
 static inline bool irq_is_pending(struct vgic_irq *irq)
 {
 	if (irq->config == VGIC_CONFIG_EDGE)
 		return irq->pending_latch;
 	else
-		return irq->pending_latch || irq->line_level;
+		return irq->pending_latch || irq_line_level(irq);
 }
 
+#define is_unshared_mapped(i) \
+((i)->hw && (i)->intid >= VGIC_NR_PRIVATE_IRQS && (i)->intid < 1020)
+
 /*
  * This struct provides an intermediate representation of the fields contained
  * in the GICH_VMCR and ICH_VMCR registers, such that code exporting the GIC
-- 
2.5.5