[v6,10/33] hw/intc/i8259: Introduce i8259 proxy TYPE_ISA_PIC

Commit Message

Bernhard Beschow Jan. 9, 2023, 5:23 p.m. UTC

Having an i8259 proxy allows for ISA PICs to be created and wired up in
southbridges. This is especially interesting for PIIX3 for two reasons:
First, the southbridge doesn't need to care about the virtualization
technology used (KVM, TCG, Xen) due to in-IRQs (where devices get
attached) and out-IRQs (which will trigger the IRQs of the respective
virtualization technology) are separated. Second, since the in-IRQs are
populated with fully initialized qemu_irq's, they can already be wired
up inside PIIX3.

Cc: Mark Cave-Ayland <[e-mail]>
Signed-off-by: Bernhard Beschow <[e-mail]>
Reviewed-by: Michael S. Tsirkin <[e-mail]>
Reviewed-by: Mark Cave-Ayland <[e-mail]>
---
 include/hw/intc/i8259.h | 18 ++++++++++++++++++
 hw/intc/i8259.c         | 27 +++++++++++++++++++++++++++
 2 files changed, 45 insertions(+)

Comments

Philippe Mathieu-Daudé Jan. 12, 2023, 12:40 p.m. UTC | #1

On 9/1/23 18:23, Bernhard Beschow wrote:
> Having an i8259 proxy allows for ISA PICs to be created and wired up in
> southbridges. This is especially interesting for PIIX3 for two reasons:
> First, the southbridge doesn't need to care about the virtualization
> technology used (KVM, TCG, Xen) due to in-IRQs (where devices get
> attached) and out-IRQs (which will trigger the IRQs of the respective
> virtualization technology) are separated. Second, since the in-IRQs are
> populated with fully initialized qemu_irq's, they can already be wired
> up inside PIIX3.
> 
> Cc: Mark Cave-Ayland <[e-mail]>
> Signed-off-by: Bernhard Beschow <[e-mail]>
> Reviewed-by: Michael S. Tsirkin <[e-mail]>
> Reviewed-by: Mark Cave-Ayland <[e-mail]>
> ---
>   include/hw/intc/i8259.h | 18 ++++++++++++++++++
>   hw/intc/i8259.c         | 27 +++++++++++++++++++++++++++
>   2 files changed, 45 insertions(+)

Reviewed-by: Philippe Mathieu-Daudé <[e-mail]>

Patch

diff --git a/include/hw/intc/i8259.h b/include/hw/intc/i8259.h
index a0e34dd990..7fb403971c 100644
--- a/include/hw/intc/i8259.h
+++ b/include/hw/intc/i8259.h
@@ -1,6 +1,24 @@ 
 #ifndef HW_I8259_H
 #define HW_I8259_H
 
+#include "qom/object.h"
+#include "hw/isa/isa.h"
+#include "qemu/typedefs.h"
+
+#define TYPE_ISA_PIC "isa-pic"
+OBJECT_DECLARE_SIMPLE_TYPE(ISAPICState, ISA_PIC)
+
+/*
+ * TYPE_ISA_PIC is currently a PIC proxy which allows for interrupt wiring in
+ * a virtualization technology agnostic way.
+ */
+struct ISAPICState {
+    DeviceState parent_obj;
+
+    qemu_irq in_irqs[ISA_NUM_IRQS];
+    qemu_irq out_irqs[ISA_NUM_IRQS];
+};
+
 /* i8259.c */
 
 extern PICCommonState *isa_pic;
diff --git a/hw/intc/i8259.c b/hw/intc/i8259.c
index 0261f087b2..e99d02136d 100644
--- a/hw/intc/i8259.c
+++ b/hw/intc/i8259.c
@@ -455,9 +455,36 @@  static const TypeInfo i8259_info = {
     .class_size = sizeof(PICClass),
 };
 
+static void isapic_set_irq(void *opaque, int irq, int level)
+{
+    ISAPICState *s = opaque;
+
+    qemu_set_irq(s->out_irqs[irq], level);
+}
+
+static void isapic_init(Object *obj)
+{
+    ISAPICState *s = ISA_PIC(obj);
+
+    qdev_init_gpio_in(DEVICE(s), isapic_set_irq, ISA_NUM_IRQS);
+    qdev_init_gpio_out(DEVICE(s), s->out_irqs, ISA_NUM_IRQS);
+
+    for (int i = 0; i < ISA_NUM_IRQS; ++i) {
+        s->in_irqs[i] = qdev_get_gpio_in(DEVICE(s), i);
+    }
+}
+
+static const TypeInfo isapic_info = {
+    .name          = TYPE_ISA_PIC,
+    .parent        = TYPE_DEVICE,
+    .instance_size = sizeof(ISAPICState),
+    .instance_init = isapic_init,
+};
+
 static void pic_register_types(void)
 {
     type_register_static(&i8259_info);
+    type_register_static(&isapic_info);
 }
 
 type_init(pic_register_types)