[RFC v2 9/9] KVM: KVM-VFIO: ARM forwarding control

Eric Auger
2014-09-01T12:52:48Z

Enables forwarding control for ARM. By defining
__KVM_HAVE_ARCH_KVM_VFIO_FORWARD the patch enables
KVM_DEV_VFIO_DEVICE_FORWARD/UNFORWARD_IRQ command on ARM. As a
result it brings an optimized injection/completion handling for
forwarded IRQ. The ARM specific part is implemented in a new module,
kvm_vfio_arm.c

Signed-off-by: Eric Auger <eric.auger@linaro.org>
---
arch/arm/include/asm/kvm_host.h | 2 +
arch/arm/kvm/Makefile | 2 +-
arch/arm/kvm/kvm_vfio_arm.c | 85 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 88 insertions(+), 1 deletion(-)
create mode 100644 arch/arm/kvm/kvm_vfio_arm.c

diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index 1aee6bb..dfd3b05 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -25,6 +25,8 @@
#include <asm/fpstate.h>
#include <kvm/arm_arch_timer.h>

+#define __KVM_HAVE_ARCH_KVM_VFIO_FORWARD
+
#if defined(CONFIG_KVM_ARM_MAX_VCPUS)
#define KVM_MAX_VCPUS CONFIG_KVM_ARM_MAX_VCPUS
#else
diff --git a/arch/arm/kvm/Makefile b/arch/arm/kvm/Makefile
index ea1fa76..26a5a42 100644
--- a/arch/arm/kvm/Makefile
+++ b/arch/arm/kvm/Makefile
@@ -19,7 +19,7 @@ kvm-arm-y = $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o $(KVM)/eventfd.o $(KVM)/vf

obj-y += kvm-arm.o init.o interrupts.o
obj-y += arm.o handle_exit.o guest.o mmu.o emulate.o reset.o
-obj-y += coproc.o coproc_a15.o coproc_a7.o mmio.o psci.o perf.o
+obj-y += coproc.o coproc_a15.o coproc_a7.o mmio.o psci.o perf.o kvm_vfio_arm.o
obj-$(CONFIG_KVM_ARM_VGIC) += $(KVM)/arm/vgic.o
obj-$(CONFIG_KVM_ARM_VGIC) += $(KVM)/arm/vgic-v2.o
obj-$(CONFIG_KVM_ARM_TIMER) += $(KVM)/arm/arch_timer.o
diff --git a/arch/arm/kvm/kvm_vfio_arm.c b/arch/arm/kvm/kvm_vfio_arm.c
new file mode 100644
index 0000000..0d316b1
--- /dev/null
+++ b/arch/arm/kvm/kvm_vfio_arm.c
@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2014 Linaro Ltd.
+ * Authors: Eric Auger <eric.auger@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2, as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/errno.h>
+#include <linux/file.h>
+#include <linux/kvm_host.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/vfio.h>
+#include <linux/irq.h>
+#include <asm/kvm_host.h>
+#include <asm/kvm.h>
+#include <linux/irq.h>
+#include <linux/platform_device.h>
+#include <linux/interrupt.h>
+
+/**
+ * kvm_arch_set_fwd_state - change the forwarded state of an IRQ
+ * @pfwd: the forwarded irq struct
+ * @action: action to perform (set forward, set back normal, cleanup)
+ *
+ * programs the GIC and VGIC
+ * returns the VGIC map/unmap return status
+ * It is the responsability of the caller to make sure the physical IRQ
+ * is not active. there is a critical section between the start of the
+ * VFIO IRQ handler and LR programming.
+ */
+int kvm_arch_set_fwd_state(struct kvm_fwd_irq *pfwd,
+ enum kvm_fwd_irq_action action)
+{
+ int ret;
+ struct irq_desc *desc = irq_to_desc(pfwd->hwirq);
+ struct irq_data *d = &desc->irq_data;
+ struct irq_chip *chip = desc->irq_data.chip;
+
+ disable_irq(pfwd->hwirq);
+ /* no fwd state change can happen if the IRQ is in progress */
+ if (irqd_irq_inprogress(d)) {
+ kvm_err("%s cannot change fwd state (IRQ %d in progress\n",
+ __func__, pfwd->hwirq);
+ enable_irq(pfwd->hwirq);
+ return -1;
+ }
+
+ if (action == KVM_VFIO_IRQ_SET_FORWARD) {
+ irqd_set_irq_forwarded(d);
+ ret = vgic_map_phys_irq(pfwd->vcpu,
+ pfwd->gsi + VGIC_NR_PRIVATE_IRQS,
+ pfwd->hwirq);
+ } else if (action == KVM_VFIO_IRQ_SET_NORMAL) {
+ irqd_clr_irq_forwarded(d);
+ ret = vgic_unmap_phys_irq(pfwd->vcpu,
+ pfwd->gsi +
+ VGIC_NR_PRIVATE_IRQS,
+ pfwd->hwirq);
+ } else if (action == KVM_VFIO_IRQ_CLEANUP) {
+ irqd_clr_irq_forwarded(d);
+ /*
+ * in case the guest did not complete the
+ * virtual IRQ, let's do it for him.
+ * when cleanup is called, VCPU have already
+ * been freed, do not manipulate VGIC
+ */
+ chip->irq_eoi(d);
+ ret = 0;
+ } else {
+ enable_irq(pfwd->hwirq);
+ ret = -EINVAL;
+ }
+
+ enable_irq(pfwd->hwirq);
+ return ret;
+}
--
1.9.1