[PATCH v2 8/8] KVM: arm/arm64: register DEOI irq bypass consumer on ARM/ARM64

[Eric Auger <eric.auger@xxxxxxxxxx>]

This patch selects IRQ_BYPASS_MANAGER and HAVE_KVM_IRQ_BYPASS
configs for ARM/ARM64.

kvm_arch_has_irq_bypass() now is implemented and returns true.
As a consequence the irq bypass consumer will be registered for
ARM/ARM64 with Direct EOI/IRQ forwarding callbacks:

- stop/start: halt/resume guest execution
- add/del_producer: set/unset forwarding/DEOI at vgic/irqchip level

The consumer currently only works with a VFIO_PLATFORM producer.
In other cases, start/stop do nothing and return without error
to avoid outputting a spurious warning.

Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>

---

v1 -> v2:
- check the type of the producer to avoid attachement with VFIO-PCI
  dummy MSI producer
---
 arch/arm/kvm/Kconfig   |  3 +++
 arch/arm64/kvm/Kconfig |  3 +++
 virt/kvm/arm/arm.c     | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 54 insertions(+)

diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig
index 90d0176..4e2b192 100644
--- a/arch/arm/kvm/Kconfig
+++ b/arch/arm/kvm/Kconfig
@@ -3,6 +3,7 @@
 #
 
 source "virt/kvm/Kconfig"
+source "virt/lib/Kconfig"
 
 menuconfig VIRTUALIZATION
 	bool "Virtualization"
@@ -35,6 +36,8 @@ config KVM
 	select HAVE_KVM_IRQCHIP
 	select HAVE_KVM_IRQ_ROUTING
 	select HAVE_KVM_MSI
+	select IRQ_BYPASS_MANAGER
+	select HAVE_KVM_IRQ_BYPASS
 	depends on ARM_VIRT_EXT && ARM_LPAE && ARM_ARCH_TIMER
 	---help---
 	  Support hosting virtualized guest machines.
diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index 52cb7ad..7e0d6e6 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -3,6 +3,7 @@
 #
 
 source "virt/kvm/Kconfig"
+source "virt/lib/Kconfig"
 
 menuconfig VIRTUALIZATION
 	bool "Virtualization"
@@ -35,6 +36,8 @@ config KVM
 	select HAVE_KVM_MSI
 	select HAVE_KVM_IRQCHIP
 	select HAVE_KVM_IRQ_ROUTING
+	select IRQ_BYPASS_MANAGER
+	select HAVE_KVM_IRQ_BYPASS
 	---help---
 	  Support hosting virtualized guest machines.
 	  We don't support KVM with 16K page tables yet, due to the multiple
diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index 3417e18..58871f8 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -27,6 +27,8 @@
 #include <linux/mman.h>
 #include <linux/sched.h>
 #include <linux/kvm.h>
+#include <linux/kvm_irqfd.h>
+#include <linux/irqbypass.h>
 #include <trace/events/kvm.h>
 #include <kvm/arm_pmu.h>
 
@@ -1420,6 +1422,52 @@ struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr)
 	return NULL;
 }
 
+bool kvm_arch_has_irq_bypass(void)
+{
+	return true;
+}
+
+int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *cons,
+				      struct irq_bypass_producer *prod)
+{
+	struct kvm_kernel_irqfd *irqfd =
+		container_of(cons, struct kvm_kernel_irqfd, consumer);
+
+	if (prod->type != IRQ_BYPASS_VFIO_PLATFORM)
+		return 0;
+
+	return kvm_vgic_set_forwarding(irqfd->kvm, prod->irq,
+				       irqfd->gsi + VGIC_NR_PRIVATE_IRQS);
+}
+void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *cons,
+				      struct irq_bypass_producer *prod)
+{
+	struct kvm_kernel_irqfd *irqfd =
+		container_of(cons, struct kvm_kernel_irqfd, consumer);
+
+	if (prod->type != IRQ_BYPASS_VFIO_PLATFORM)
+		return;
+
+	kvm_vgic_unset_forwarding(irqfd->kvm, prod->irq,
+				  irqfd->gsi + VGIC_NR_PRIVATE_IRQS);
+}
+
+void kvm_arch_irq_bypass_stop(struct irq_bypass_consumer *cons)
+{
+	struct kvm_kernel_irqfd *irqfd =
+		container_of(cons, struct kvm_kernel_irqfd, consumer);
+
+	kvm_arm_halt_guest(irqfd->kvm);
+}
+
+void kvm_arch_irq_bypass_start(struct irq_bypass_consumer *cons)
+{
+	struct kvm_kernel_irqfd *irqfd =
+		container_of(cons, struct kvm_kernel_irqfd, consumer);
+
+	kvm_arm_resume_guest(irqfd->kvm);
+}
+
 /**
  * Initialize Hyp-mode and memory mappings on all CPUs.
  */
-- 
2.5.5