[Qemu-devel] [RFC] in-kernel irqchip : split devices

[Glauber Costa <glommer@redhat.com>]

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Hello people,

As I promised, I am sending a very brief PoC wrt split devices and in-kernel irqchip.
In this mail, I am including only the ioapic version for apreciation. I also have i8259,
and apic will take me a little bit more. This is just to try to bind the discussion to real
code.

Note that we end up with a very slim representation of the device, and the code is much less
confusing, IMHO.



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Index: qemu/Makefile.target
===================================================================
--- qemu.orig/Makefile.target
+++ qemu/Makefile.target
@@ -197,6 +197,8 @@ obj-i386-y += usb-uhci.o vmmouse.o vmpor
 obj-i386-y += device-hotplug.o pci-hotplug.o smbios.o wdt_ib700.o
 obj-i386-y += ne2000-isa.o
 
+obj-i386-$(CONFIG_KVM) += ioapic-kvm.o
+
 # shared objects
 obj-ppc-y = ppc.o ide/core.o ide/qdev.o ide/isa.o ide/pci.o ide/macio.o
 obj-ppc-y += vga.o vga-pci.o $(sound-obj-y) dma.o openpic.o
Index: qemu/hw/ioapic-kvm.c
===================================================================
--- /dev/null
+++ qemu/hw/ioapic-kvm.c
@@ -0,0 +1,81 @@
+#include "hw.h"
+#include "pc.h"
+#include "qemu-timer.h"
+#include "host-utils.h"
+#include "kvm.h"
+
+#define IOAPIC_NUM_PINS			0x18
+#define IOAPIC_DEFAULT_BASE_ADDRESS  0xfec00000
+
+static void ioapic_reset(void *opaque)
+{
+    struct kvm_ioapic_state *s = opaque;
+    struct kvm_irqchip *chip;
+    int i;
+
+    chip = container_of(s, struct kvm_irqchip, chip.ioapic);
+
+    chip->chip_id = KVM_IRQCHIP_IOAPIC;
+
+    memset(s, 0, sizeof(*s));
+    s->base_address = IOAPIC_DEFAULT_BASE_ADDRESS;
+    for(i = 0; i < IOAPIC_NUM_PINS; i++)
+        s->redirtbl[i].bits = 1 << 16; /* mask LVT */
+
+    kvm_set_irqchip(chip);
+}
+
+static void ioapic_pre_save(void *opaque)
+{
+    struct kvm_ioapic_state *s = opaque;
+    struct kvm_irqchip *chip;
+
+    chip = container_of(s, struct kvm_irqchip, chip.ioapic);
+
+    kvm_get_irqchip(chip);
+}
+
+static int ioapic_post_load(void *opaque, int version_id)
+{
+    struct kvm_ioapic_state *s = opaque;
+    struct kvm_irqchip *chip;
+
+    chip = container_of(s, struct kvm_irqchip, chip.ioapic);
+
+    return kvm_set_irqchip(chip);
+}
+
+static const VMStateDescription vmstate_kvm_ioapic = {
+    .name = "ioapic-kvm",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .post_load = ioapic_post_load,
+    .pre_save = ioapic_pre_save,
+    .fields      = (VMStateField []) {
+        VMSTATE_U64(base_address, struct kvm_ioapic_state),
+        VMSTATE_UINT32(id, struct kvm_ioapic_state),
+        VMSTATE_UINT32(ioregsel, struct kvm_ioapic_state),
+        VMSTATE_UINT32(irr, struct kvm_ioapic_state),
+        VMSTATE_ARRAY_UNSAFE(redirtbl, struct kvm_ioapic_state, IOAPIC_NUM_PINS, 0, vmstate_info_u64, __u64),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+
+static void kvm_ioapic_set_irq(void *opaque, int vector, int level)
+{
+}
+
+qemu_irq *kvm_ioapic_init(void)
+{
+    struct kvm_irqchip *s;
+
+    s = qemu_mallocz(sizeof(*s));
+
+    ioapic_reset(&s->chip.ioapic);
+
+    vmstate_register(0, &vmstate_kvm_ioapic, &s->chip.ioapic);
+    qemu_register_reset(ioapic_reset, &s->chip.ioapic);
+
+    return qemu_allocate_irqs(kvm_ioapic_set_irq, &s->chip.ioapic, IOAPIC_NUM_PINS);
+}
Index: qemu/hw/pc.h
===================================================================
--- qemu.orig/hw/pc.h
+++ qemu/hw/pc.h
@@ -48,6 +48,8 @@ void ioapic_set_irq(void *opaque, int ve
 void apic_reset_irq_delivered(void);
 int apic_get_irq_delivered(void);
 
+qemu_irq *kvm_ioapic_init(void);
+
 /* i8254.c */
 
 #define PIT_FREQ 1193182
Index: qemu/kvm-all.c
===================================================================
--- qemu.orig/kvm-all.c
+++ qemu/kvm-all.c
@@ -411,6 +411,26 @@ int kvm_check_extension(KVMState *s, uns
     return ret;
 }
 
+#ifdef KVM_CAP_IRQCHIP
+int kvm_set_irqchip(struct kvm_irqchip *chip)
+{
+    if (!kvm_state->irqchip_in_kernel) {
+        return 0;
+    }
+
+    return kvm_vm_ioctl(kvm_state, KVM_SET_IRQCHIP, chip);
+}
+
+int kvm_get_irqchip(struct kvm_irqchip *chip)
+{
+    if (!kvm_state->irqchip_in_kernel) {
+        return 0;
+    }
+
+    return kvm_vm_ioctl(kvm_state, KVM_GET_IRQCHIP, chip);
+}
+#endif
+
 int kvm_init(int smp_cpus)
 {
     static const char upgrade_note[] =
Index: qemu/kvm.h
===================================================================
--- qemu.orig/kvm.h
+++ qemu/kvm.h
@@ -16,6 +16,7 @@
 
 #include "config.h"
 #include "qemu-queue.h"
+#include <linux/kvm.h>
 
 #ifdef CONFIG_KVM
 extern int kvm_allowed;
@@ -63,6 +64,9 @@ int kvm_update_guest_debug(CPUState *env
 int kvm_pit_in_kernel(void);
 int kvm_irqchip_in_kernel(void);
 
+int kvm_set_irqchip(struct kvm_irqchip *chip);
+int kvm_get_irqchip(struct kvm_irqchip *chip);
+
 /* internal API */
 
 struct KVMState;