[PATCH 1/3] KVM: Introduce KVM_EXIT_IRQ

[Pavel Fedin]

This exit code means that this vCPU wants to inject an interrupt using
userspace-emulated controller.

IRQs are signalled by adding pending interrupt descriptors to vcpu
structure. For simplicity, we currently reserve only one pointer for a
single interrupt, which will be used by ARM virtual timer code. This can
be extended in the future if necessary.

The interface is designed to be as much arch-agnostic as possible.
Therefore, it has IRQ number and level as parameters (encoded in
struct kvm_irq_level).

Signed-off-by: Pavel Fedin <p.fe...@samsung.com>
---
 arch/arm/kvm/arm.c       | 6 ++++++
 include/linux/kvm_host.h | 7 +++++++
 include/uapi/linux/kvm.h | 3 +++
 3 files changed, 16 insertions(+)

diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 66f90c1..6392a5b 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -585,6 +585,12 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct 
kvm_run *run)
                if (signal_pending(current)) {
                        ret = -EINTR;
                        run->exit_reason = KVM_EXIT_INTR;
+               } else if (vcpu->irq) {
+                       ret = 0;
+                       run->exit_reason = KVM_EXIT_IRQ;
+                       run->irq.irq = vcpu->irq->irq;
+                       run->irq.level = vcpu->irq->level;
+                       vcpu->irq = NULL;
                }
 
                if (ret <= 0 || need_new_vmid_gen(vcpu->kvm) ||
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index c923350..93f59c5 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -281,6 +281,13 @@ struct kvm_vcpu {
        } spin_loop;
 #endif
        bool preempted;
+
+       /*
+        * IRQ pending to the userspace on this CPU.
+        * Currently we support only one slot, used only by ARM architecture.
+        */
+       const struct kvm_irq_level *irq;
+
        struct kvm_vcpu_arch arch;
 };
 
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 03f3618..a717a9b 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -184,6 +184,7 @@ struct kvm_s390_skeys {
 #define KVM_EXIT_SYSTEM_EVENT     24
 #define KVM_EXIT_S390_STSI        25
 #define KVM_EXIT_IOAPIC_EOI       26
+#define KVM_EXIT_IRQ              27
 
 /* For KVM_EXIT_INTERNAL_ERROR */
 /* Emulate instruction failed. */
@@ -338,6 +339,8 @@ struct kvm_run {
                struct {
                        __u8 vector;
                } eoi;
+               /* KVM_EXIT_IRQ */
+               struct kvm_irq_level irq;
                /* Fix the size of the union. */
                char padding[256];
        };
-- 
2.4.4

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