[Qemu-devel] [PATCH v4 13/15] kvm: x86: Add user space part for in-kernel i8259

[Jan Kiszka]

Introduce the alternative i8259 backend that exploits KVM in-kernel
acceleration.

The PIIX3 initialization code is furthermore extended by KVM specific
IRQ route setup. GSI injection differs in KVM mode from the user space
model. As we can dispatch ISA-range IRQs to both IOAPIC and PIC inside
the kernel, we do not need to inject them separately. This is reflected
by a KVM-specific GSI handler.

Signed-off-by: Jan Kiszka <address@hidden>
---
 Makefile.target |    2 +-
 hw/kvm/i8259.c  |  126 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 hw/pc.h         |    1 +
 hw/pc_piix.c    |   50 ++++++++++++++++++++--
 4 files changed, 174 insertions(+), 5 deletions(-)
 create mode 100644 hw/kvm/i8259.c

diff --git a/Makefile.target b/Makefile.target
index 76de485..fb10143 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -236,7 +236,7 @@ obj-i386-y += vmport.o
 obj-i386-y += device-hotplug.o pci-hotplug.o smbios.o wdt_ib700.o
 obj-i386-y += debugcon.o multiboot.o
 obj-i386-y += pc_piix.o
-obj-i386-$(CONFIG_KVM) += kvm/clock.o kvm/apic.o
+obj-i386-$(CONFIG_KVM) += kvm/clock.o kvm/apic.o kvm/i8259.o
 obj-i386-$(CONFIG_SPICE) += qxl.o qxl-logger.o qxl-render.o
 
 # shared objects
diff --git a/hw/kvm/i8259.c b/hw/kvm/i8259.c
new file mode 100644
index 0000000..98d7141
--- /dev/null
+++ b/hw/kvm/i8259.c
@@ -0,0 +1,126 @@
+/*
+ * KVM in-kernel PIC (i8259) support
+ *
+ * Copyright (c) 2011 Siemens AG
+ *
+ * Authors:
+ *  Jan Kiszka          <address@hidden>
+ *
+ * This work is licensed under the terms of the GNU GPL version 2.
+ * See the COPYING file in the top-level directory.
+ */
+#include "hw/i8259_internal.h"
+#include "hw/apic_internal.h"
+#include "kvm.h"
+
+static void kvm_pic_get(PicState *s)
+{
+    struct kvm_irqchip chip;
+    struct kvm_pic_state *kpic;
+    int ret;
+
+    chip.chip_id = s->master ? KVM_IRQCHIP_PIC_MASTER : KVM_IRQCHIP_PIC_SLAVE;
+    ret = kvm_vm_ioctl(kvm_state, KVM_GET_IRQCHIP, &chip);
+    if (ret < 0) {
+        fprintf(stderr, "KVM_GET_IRQCHIP failed: %s\n", strerror(ret));
+        abort();
+    }
+
+    kpic = &chip.chip.pic;
+
+    s->last_irr = kpic->last_irr;
+    s->irr = kpic->irr;
+    s->imr = kpic->imr;
+    s->isr = kpic->isr;
+    s->priority_add = kpic->priority_add;
+    s->irq_base = kpic->irq_base;
+    s->read_reg_select = kpic->read_reg_select;
+    s->poll = kpic->poll;
+    s->special_mask = kpic->special_mask;
+    s->init_state = kpic->init_state;
+    s->auto_eoi = kpic->auto_eoi;
+    s->rotate_on_auto_eoi = kpic->rotate_on_auto_eoi;
+    s->special_fully_nested_mode = kpic->special_fully_nested_mode;
+    s->init4 = kpic->init4;
+    s->elcr = kpic->elcr;
+    s->elcr_mask = kpic->elcr_mask;
+}
+
+static void kvm_pic_put(PicState *s)
+{
+    struct kvm_irqchip chip;
+    struct kvm_pic_state *kpic;
+    int ret;
+
+    chip.chip_id = s->master ? KVM_IRQCHIP_PIC_MASTER : KVM_IRQCHIP_PIC_SLAVE;
+
+    kpic = &chip.chip.pic;
+
+    kpic->last_irr = s->last_irr;
+    kpic->irr = s->irr;
+    kpic->imr = s->imr;
+    kpic->isr = s->isr;
+    kpic->priority_add = s->priority_add;
+    kpic->irq_base = s->irq_base;
+    kpic->read_reg_select = s->read_reg_select;
+    kpic->poll = s->poll;
+    kpic->special_mask = s->special_mask;
+    kpic->init_state = s->init_state;
+    kpic->auto_eoi = s->auto_eoi;
+    kpic->rotate_on_auto_eoi = s->rotate_on_auto_eoi;
+    kpic->special_fully_nested_mode = s->special_fully_nested_mode;
+    kpic->init4 = s->init4;
+    kpic->elcr = s->elcr;
+    kpic->elcr_mask = s->elcr_mask;
+
+    ret = kvm_vm_ioctl(kvm_state, KVM_SET_IRQCHIP, &chip);
+    if (ret < 0) {
+        fprintf(stderr, "KVM_GET_IRQCHIP failed: %s\n", strerror(ret));
+        abort();
+    }
+}
+
+static void kvm_pic_reset(PicState *s)
+{
+    pic_reset_internal(s);
+    s->elcr = 0;
+
+    kvm_pic_put(s);
+}
+
+static void kvm_pic_set_irq(void *opaque, int irq, int level)
+{
+    int delivered;
+
+    delivered = kvm_irqchip_set_irq(kvm_state, irq, level);
+    apic_set_irq_delivered(delivered);
+}
+
+static void kvm_pic_backend_init(PicState *s)
+{
+    memory_region_init_reservation(&s->base_io, "kvm-pic", 2);
+    memory_region_init_reservation(&s->elcr_io, "kvm-elcr", 1);
+}
+
+qemu_irq *kvm_i8259_init(void)
+{
+    i8259_init_chip(true, "KVM");
+    i8259_init_chip(false, "KVM");
+
+    return qemu_allocate_irqs(kvm_pic_set_irq, NULL, ISA_NUM_IRQS);
+}
+
+static PICBackend kvm_pic_backend = {
+    .name = "KVM",
+    .init = kvm_pic_backend_init,
+    .reset = kvm_pic_reset,
+    .pre_save = kvm_pic_get,
+    .post_load = kvm_pic_put,
+};
+
+static void kvm_pic_register(void)
+{
+    pic_register_backend(&kvm_pic_backend);
+}
+
+device_init(kvm_pic_register)
diff --git a/hw/pc.h b/hw/pc.h
index b7b7e40..fc6f446 100644
--- a/hw/pc.h
+++ b/hw/pc.h
@@ -64,6 +64,7 @@ bool parallel_mm_init(MemoryRegion *address_space,
 typedef struct PicState PicState;
 extern PicState *isa_pic;
 qemu_irq *i8259_init(qemu_irq parent_irq);
+qemu_irq *kvm_i8259_init(void);
 int pic_read_irq(PicState *s);
 int pic_get_output(PicState *s);
 void pic_info(Monitor *mon);
diff --git a/hw/pc_piix.c b/hw/pc_piix.c
index 98f2822..8650319 100644
--- a/hw/pc_piix.c
+++ b/hw/pc_piix.c
@@ -53,6 +53,40 @@ static const int ide_iobase[MAX_IDE_BUS] = { 0x1f0, 0x170 };
 static const int ide_iobase2[MAX_IDE_BUS] = { 0x3f6, 0x376 };
 static const int ide_irq[MAX_IDE_BUS] = { 14, 15 };
 
+static void kvm_piix3_setup_irq_routing(bool pci_enabled)
+{
+    KVMState *s = kvm_state;
+    int ret, i;
+
+    if (kvm_check_extension(s, KVM_CAP_IRQ_ROUTING)) {
+        for (i = 0; i < 8; ++i) {
+            if (i == 2) {
+                continue;
+            }
+            kvm_irqchip_add_route(s, i, KVM_IRQCHIP_PIC_MASTER, i);
+        }
+        for (i = 8; i < 16; ++i) {
+            kvm_irqchip_add_route(s, i, KVM_IRQCHIP_PIC_SLAVE, i - 8);
+        }
+        ret = kvm_irqchip_commit_routes(s);
+        if (ret < 0) {
+            hw_error("KVM IRQ routing setup failed");
+        }
+    }
+}
+
+static void kvm_piix3_gsi_handler(void *opaque, int n, int level)
+{
+    GSIState *s = opaque;
+
+    if (n < ISA_NUM_IRQS) {
+        /* Kernel will forward to both PIC and IOAPIC */
+        qemu_set_irq(s->i8259_irq[n], level);
+    } else {
+        qemu_set_irq(s->ioapic_irq[n], level);
+    }
+}
+
 static void ioapic_init(GSIState *gsi_state)
 {
     DeviceState *dev;
@@ -133,7 +167,13 @@ static void pc_init1(MemoryRegion *system_memory,
     }
 
     gsi_state = g_malloc0(sizeof(*gsi_state));
-    gsi = qemu_allocate_irqs(gsi_handler, gsi_state, GSI_NUM_PINS);
+    if (kvm_enabled() && kvm_irqchip_in_kernel()) {
+        kvm_piix3_setup_irq_routing(pci_enabled);
+        gsi = qemu_allocate_irqs(kvm_piix3_gsi_handler, gsi_state,
+                                 GSI_NUM_PINS);
+    } else {
+        gsi = qemu_allocate_irqs(gsi_handler, gsi_state, GSI_NUM_PINS);
+    }
 
     if (pci_enabled) {
         pci_bus = i440fx_init(&i440fx_state, &piix3_devfn, gsi,
@@ -153,11 +193,13 @@ static void pc_init1(MemoryRegion *system_memory,
     }
     isa_bus_irqs(gsi);
 
-    if (!xen_enabled()) {
+    if (kvm_enabled() && kvm_irqchip_in_kernel()) {
+        i8259 = kvm_i8259_init();
+    } else if (xen_enabled()) {
+        i8259 = xen_interrupt_controller_init();
+    } else {
         cpu_irq = pc_allocate_cpu_irq();
         i8259 = i8259_init(cpu_irq[0]);
-    } else {
-        i8259 = xen_interrupt_controller_init();
     }
 
     for (i = 0; i < ISA_NUM_IRQS; i++) {
-- 
1.7.3.4