[PATCH 0/4] hw/i386/pc: Extract the port92 device

[PATCH 0/4] hw/i386/pc: Extract the port92 device

[Philippe Mathieu-Daudé]

In this series we
- remove the old DPRINTF() macro in hw/i386/pc.c
- extract the TYPE_PORT92 device from the same file,
  reducing it by 5%.

Philippe Mathieu-Daudé (4):
  hw/i386/pc: Convert DPRINTF() to trace events
  hw/i386/pc: Use TYPE_PORT92 instead of hardcoded string
  hw/i386/pc: Inline port92_init()
  hw/i386/pc: Extract the port92 device

 include/hw/i386/pc.h  |   3 +
 hw/i386/pc.c          | 138 ++----------------------------------------
 hw/i386/port92.c      | 126 ++++++++++++++++++++++++++++++++++++++
 hw/i386/Makefile.objs |   1 +
 hw/i386/trace-events  |   8 +++
 5 files changed, 144 insertions(+), 132 deletions(-)
 create mode 100644 hw/i386/port92.c

-- 
2.21.0

[PATCH 1/4] hw/i386/pc: Convert DPRINTF() to trace events

[Philippe Mathieu-Daudé]

Convert the deprecated DPRINTF() macro to trace events.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 hw/i386/pc.c         | 19 +++++--------------
 hw/i386/trace-events |  6 ++++++
 2 files changed, 11 insertions(+), 14 deletions(-)

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index ac08e63604..66a30cfdf5 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -90,16 +90,7 @@
 #include "config-devices.h"
 #include "e820_memory_layout.h"
 #include "fw_cfg.h"
-
-/* debug PC/ISA interrupts */
-//#define DEBUG_IRQ
-
-#ifdef DEBUG_IRQ
-#define DPRINTF(fmt, ...)                                       \
-    do { printf("CPUIRQ: " fmt , ## __VA_ARGS__); } while (0)
-#else
-#define DPRINTF(fmt, ...)
-#endif
+#include "trace.h"
 
 struct hpet_fw_config hpet_cfg = {.count = UINT8_MAX};
 
@@ -348,7 +339,7 @@ void gsi_handler(void *opaque, int n, int level)
 {
     GSIState *s = opaque;
 
-    DPRINTF("pc: %s GSI %d\n", level ? "raising" : "lowering", n);
+    trace_pc_gsi_interrupt(n, level);
     if (n < ISA_NUM_IRQS) {
         qemu_set_irq(s->i8259_irq[n], level);
     }
@@ -426,7 +417,7 @@ static void pic_irq_request(void *opaque, int irq, int level)
     CPUState *cs = first_cpu;
     X86CPU *cpu = X86_CPU(cs);
 
-    DPRINTF("pic_irqs: %s irq %d\n", level? "raise" : "lower", irq);
+    trace_pc_pic_interrupt(irq, level);
     if (cpu->apic_state && !kvm_irqchip_in_kernel()) {
         CPU_FOREACH(cs) {
             cpu = X86_CPU(cs);
@@ -760,7 +751,7 @@ static void port92_write(void *opaque, hwaddr addr, uint64_t val,
     Port92State *s = opaque;
     int oldval = s->outport;
 
-    DPRINTF("port92: write 0x%02" PRIx64 "\n", val);
+    trace_port92_write(val);
     s->outport = val;
     qemu_set_irq(s->a20_out, (val >> 1) & 1);
     if ((val & 1) && !(oldval & 1)) {
@@ -775,7 +766,7 @@ static uint64_t port92_read(void *opaque, hwaddr addr,
     uint32_t ret;
 
     ret = s->outport;
-    DPRINTF("port92: read 0x%02x\n", ret);
+    trace_port92_read(ret);
     return ret;
 }
 
diff --git a/hw/i386/trace-events b/hw/i386/trace-events
index c8bc464bc5..43f33cf7e2 100644
--- a/hw/i386/trace-events
+++ b/hw/i386/trace-events
@@ -111,3 +111,9 @@ amdvi_ir_irte_ga_val(uint64_t hi, uint64_t lo) "hi 0x%"PRIx64" lo 0x%"PRIx64
 # vmport.c
 vmport_register(unsigned char command, void *func, void *opaque) "command: 0x%02x func: %p opaque: %p"
 vmport_command(unsigned char command) "command: 0x%02x"
+
+# pc.c
+pc_gsi_interrupt(int irqn, int level) "GSI interrupt #%d level:%d"
+pc_pic_interrupt(int irqn, int level) "PIC interrupt #%d level:%d"
+port92_read(uint8_t val) "port92: read 0x%02x"
+port92_write(uint8_t val) "port92: write 0x%02x"
-- 
2.21.0

[PATCH 2/4] hw/i386/pc: Use TYPE_PORT92 instead of hardcoded string

[Philippe Mathieu-Daudé]

By using the TYPE_* definitions for devices, we can:
- quickly find where devices are used with 'git-grep'
- easily rename a device (one-line change).

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 hw/i386/pc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 66a30cfdf5..2c2ae27447 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1353,7 +1353,7 @@ static void pc_superio_init(ISABus *isa_bus, bool create_fdctrl, bool no_vmport)
         qdev_prop_set_ptr(dev, "ps2_mouse", i8042);
         qdev_init_nofail(dev);
     }
-    port92 = isa_create_simple(isa_bus, "port92");
+    port92 = isa_create_simple(isa_bus, TYPE_PORT92);
 
     a20_line = qemu_allocate_irqs(handle_a20_line_change, first_cpu, 2);
     i8042_setup_a20_line(i8042, a20_line[0]);
-- 
2.21.0

[PATCH 3/4] hw/i386/pc: Inline port92_init()

[Philippe Mathieu-Daudé]

This one-line function is not very helpful, so remove it
by inlining the call to qdev_connect_gpio_out_named().

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 hw/i386/pc.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 2c2ae27447..2e8992c7d0 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -770,11 +770,6 @@ static uint64_t port92_read(void *opaque, hwaddr addr,
     return ret;
 }
 
-static void port92_init(ISADevice *dev, qemu_irq a20_out)
-{
-    qdev_connect_gpio_out_named(DEVICE(dev), PORT92_A20_LINE, 0, a20_out);
-}
-
 static const VMStateDescription vmstate_port92_isa = {
     .name = "port92",
     .version_id = 1,
@@ -830,8 +825,8 @@ static void port92_class_initfn(ObjectClass *klass, void *data)
     dc->vmsd = &vmstate_port92_isa;
     /*
      * Reason: unlike ordinary ISA devices, this one needs additional
-     * wiring: its A20 output line needs to be wired up by
-     * port92_init().
+     * wiring: its A20 output line needs to be wired up with
+     * qdev_connect_gpio_out_named().
      */
     dc->user_creatable = false;
 }
@@ -1357,7 +1352,8 @@ static void pc_superio_init(ISABus *isa_bus, bool create_fdctrl, bool no_vmport)
 
     a20_line = qemu_allocate_irqs(handle_a20_line_change, first_cpu, 2);
     i8042_setup_a20_line(i8042, a20_line[0]);
-    port92_init(port92, a20_line[1]);
+    qdev_connect_gpio_out_named(DEVICE(port92),
+                                PORT92_A20_LINE, 0, a20_line[1]);
     g_free(a20_line);
 }
 
-- 
2.21.0

[PATCH 4/4] hw/i386/pc: Extract the port92 device

[Philippe Mathieu-Daudé]

This device is only used by the PC machines. The pc.c file is
already big enough, with 2255 lines. By removing 113 lines of
it, we reduced it by 5%. It is now a bit easier to navigate
the file.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
checkpatch warning:

  WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?
  #142:
  new file mode 100644

is harmless because MAINTAINERS PC entry matches the directory:

  PC
  ...
  F: hw/i386/
---
 include/hw/i386/pc.h  |   3 +
 hw/i386/pc.c          | 113 -------------------------------------
 hw/i386/port92.c      | 126 ++++++++++++++++++++++++++++++++++++++++++
 hw/i386/Makefile.objs |   1 +
 hw/i386/trace-events  |   2 +
 5 files changed, 132 insertions(+), 113 deletions(-)
 create mode 100644 hw/i386/port92.c

diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index 1f86eba3f9..7e8d18d6fa 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -224,8 +224,11 @@ int cmos_get_fd_drive_type(FloppyDriveType fd0);
 
 #define FW_CFG_IO_BASE     0x510
 
+/* port92.c */
 #define PORT92_A20_LINE "a20"
 
+#define TYPE_PORT92 "port92"
+
 /* hpet.c */
 extern int no_hpet;
 
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 2e8992c7d0..15efcb29d5 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -733,119 +733,6 @@ void pc_cmos_init(PCMachineState *pcms,
     qemu_register_reset(pc_cmos_init_late, &arg);
 }
 
-#define TYPE_PORT92 "port92"
-#define PORT92(obj) OBJECT_CHECK(Port92State, (obj), TYPE_PORT92)
-
-/* port 92 stuff: could be split off */
-typedef struct Port92State {
-    ISADevice parent_obj;
-
-    MemoryRegion io;
-    uint8_t outport;
-    qemu_irq a20_out;
-} Port92State;
-
-static void port92_write(void *opaque, hwaddr addr, uint64_t val,
-                         unsigned size)
-{
-    Port92State *s = opaque;
-    int oldval = s->outport;
-
-    trace_port92_write(val);
-    s->outport = val;
-    qemu_set_irq(s->a20_out, (val >> 1) & 1);
-    if ((val & 1) && !(oldval & 1)) {
-        qemu_system_reset_request(SHUTDOWN_CAUSE_GUEST_RESET);
-    }
-}
-
-static uint64_t port92_read(void *opaque, hwaddr addr,
-                            unsigned size)
-{
-    Port92State *s = opaque;
-    uint32_t ret;
-
-    ret = s->outport;
-    trace_port92_read(ret);
-    return ret;
-}
-
-static const VMStateDescription vmstate_port92_isa = {
-    .name = "port92",
-    .version_id = 1,
-    .minimum_version_id = 1,
-    .fields = (VMStateField[]) {
-        VMSTATE_UINT8(outport, Port92State),
-        VMSTATE_END_OF_LIST()
-    }
-};
-
-static void port92_reset(DeviceState *d)
-{
-    Port92State *s = PORT92(d);
-
-    s->outport &= ~1;
-}
-
-static const MemoryRegionOps port92_ops = {
-    .read = port92_read,
-    .write = port92_write,
-    .impl = {
-        .min_access_size = 1,
-        .max_access_size = 1,
-    },
-    .endianness = DEVICE_LITTLE_ENDIAN,
-};
-
-static void port92_initfn(Object *obj)
-{
-    Port92State *s = PORT92(obj);
-
-    memory_region_init_io(&s->io, OBJECT(s), &port92_ops, s, "port92", 1);
-
-    s->outport = 0;
-
-    qdev_init_gpio_out_named(DEVICE(obj), &s->a20_out, PORT92_A20_LINE, 1);
-}
-
-static void port92_realizefn(DeviceState *dev, Error **errp)
-{
-    ISADevice *isadev = ISA_DEVICE(dev);
-    Port92State *s = PORT92(dev);
-
-    isa_register_ioport(isadev, &s->io, 0x92);
-}
-
-static void port92_class_initfn(ObjectClass *klass, void *data)
-{
-    DeviceClass *dc = DEVICE_CLASS(klass);
-
-    dc->realize = port92_realizefn;
-    dc->reset = port92_reset;
-    dc->vmsd = &vmstate_port92_isa;
-    /*
-     * Reason: unlike ordinary ISA devices, this one needs additional
-     * wiring: its A20 output line needs to be wired up with
-     * qdev_connect_gpio_out_named().
-     */
-    dc->user_creatable = false;
-}
-
-static const TypeInfo port92_info = {
-    .name          = TYPE_PORT92,
-    .parent        = TYPE_ISA_DEVICE,
-    .instance_size = sizeof(Port92State),
-    .instance_init = port92_initfn,
-    .class_init    = port92_class_initfn,
-};
-
-static void port92_register_types(void)
-{
-    type_register_static(&port92_info);
-}
-
-type_init(port92_register_types)
-
 static void handle_a20_line_change(void *opaque, int irq, int level)
 {
     X86CPU *cpu = opaque;
diff --git a/hw/i386/port92.c b/hw/i386/port92.c
new file mode 100644
index 0000000000..19866c44ef
--- /dev/null
+++ b/hw/i386/port92.c
@@ -0,0 +1,126 @@
+/*
+ * QEMU I/O port 0x92 (System Control Port A, to handle Fast Gate A20)
+ *
+ * Copyright (c) 2003-2004 Fabrice Bellard
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#include "qemu/osdep.h"
+#include "sysemu/runstate.h"
+#include "migration/vmstate.h"
+#include "hw/irq.h"
+#include "hw/i386/pc.h"
+#include "trace.h"
+
+#define PORT92(obj) OBJECT_CHECK(Port92State, (obj), TYPE_PORT92)
+
+typedef struct Port92State {
+    ISADevice parent_obj;
+
+    MemoryRegion io;
+    uint8_t outport;
+    qemu_irq a20_out;
+} Port92State;
+
+static void port92_write(void *opaque, hwaddr addr, uint64_t val,
+                         unsigned size)
+{
+    Port92State *s = opaque;
+    int oldval = s->outport;
+
+    trace_port92_write(val);
+    s->outport = val;
+    qemu_set_irq(s->a20_out, (val >> 1) & 1);
+    if ((val & 1) && !(oldval & 1)) {
+        qemu_system_reset_request(SHUTDOWN_CAUSE_GUEST_RESET);
+    }
+}
+
+static uint64_t port92_read(void *opaque, hwaddr addr,
+                            unsigned size)
+{
+    Port92State *s = opaque;
+    uint32_t ret;
+
+    ret = s->outport;
+    trace_port92_read(ret);
+
+    return ret;
+}
+
+static const VMStateDescription vmstate_port92_isa = {
+    .name = "port92",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT8(outport, Port92State),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static void port92_reset(DeviceState *d)
+{
+    Port92State *s = PORT92(d);
+
+    s->outport &= ~1;
+}
+
+static const MemoryRegionOps port92_ops = {
+    .read = port92_read,
+    .write = port92_write,
+    .impl = {
+        .min_access_size = 1,
+        .max_access_size = 1,
+    },
+    .endianness = DEVICE_LITTLE_ENDIAN,
+};
+
+static void port92_initfn(Object *obj)
+{
+    Port92State *s = PORT92(obj);
+
+    memory_region_init_io(&s->io, OBJECT(s), &port92_ops, s, "port92", 1);
+
+    s->outport = 0;
+
+    qdev_init_gpio_out_named(DEVICE(obj), &s->a20_out, PORT92_A20_LINE, 1);
+}
+
+static void port92_realizefn(DeviceState *dev, Error **errp)
+{
+    ISADevice *isadev = ISA_DEVICE(dev);
+    Port92State *s = PORT92(dev);
+
+    isa_register_ioport(isadev, &s->io, 0x92);
+}
+
+static void port92_class_initfn(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->realize = port92_realizefn;
+    dc->reset = port92_reset;
+    dc->vmsd = &vmstate_port92_isa;
+    /*
+     * Reason: unlike ordinary ISA devices, this one needs additional
+     * wiring: its A20 output line needs to be wired up with
+     * qdev_connect_gpio_out_named().
+     */
+    dc->user_creatable = false;
+}
+
+static const TypeInfo port92_info = {
+    .name          = TYPE_PORT92,
+    .parent        = TYPE_ISA_DEVICE,
+    .instance_size = sizeof(Port92State),
+    .instance_init = port92_initfn,
+    .class_init    = port92_class_initfn,
+};
+
+static void port92_register_types(void)
+{
+    type_register_static(&port92_info);
+}
+
+type_init(port92_register_types)
diff --git a/hw/i386/Makefile.objs b/hw/i386/Makefile.objs
index 0d195b5210..b317e7eee0 100644
--- a/hw/i386/Makefile.objs
+++ b/hw/i386/Makefile.objs
@@ -12,6 +12,7 @@ obj-$(CONFIG_AMD_IOMMU) += amd_iommu.o
 obj-$(CONFIG_XEN) += ../xenpv/ xen/
 obj-$(CONFIG_VMPORT) += vmport.o
 obj-$(CONFIG_VMMOUSE) += vmmouse.o
+obj-$(CONFIG_PC) += port92.o
 
 obj-y += kvmvapic.o
 obj-y += acpi-build.o
diff --git a/hw/i386/trace-events b/hw/i386/trace-events
index 43f33cf7e2..076ea5dcfb 100644
--- a/hw/i386/trace-events
+++ b/hw/i386/trace-events
@@ -115,5 +115,7 @@ vmport_command(unsigned char command) "command: 0x%02x"
 # pc.c
 pc_gsi_interrupt(int irqn, int level) "GSI interrupt #%d level:%d"
 pc_pic_interrupt(int irqn, int level) "PIC interrupt #%d level:%d"
+
+# port92.c
 port92_read(uint8_t val) "port92: read 0x%02x"
 port92_write(uint8_t val) "port92: write 0x%02x"
-- 
2.21.0

Re: [PATCH 4/4] hw/i386/pc: Extract the port92 device

[Paolo Bonzini]

On 13/12/19 11:51, Philippe Mathieu-Daudé wrote:
> This device is only used by the PC machines. The pc.c file is
> already big enough, with 2255 lines. By removing 113 lines of
> it, we reduced it by 5%. It is now a bit easier to navigate
> the file.
> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
> checkpatch warning:
> 
>   WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?
>   #142:
>   new file mode 100644
> 
> is harmless because MAINTAINERS PC entry matches the directory:
> 
>   PC
>   ...
>   F: hw/i386/
> ---
>  include/hw/i386/pc.h  |   3 +
>  hw/i386/pc.c          | 113 -------------------------------------
>  hw/i386/port92.c      | 126 ++++++++++++++++++++++++++++++++++++++++++
>  hw/i386/Makefile.objs |   1 +
>  hw/i386/trace-events  |   2 +
>  5 files changed, 132 insertions(+), 113 deletions(-)
>  create mode 100644 hw/i386/port92.c
> 
> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> index 1f86eba3f9..7e8d18d6fa 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -224,8 +224,11 @@ int cmos_get_fd_drive_type(FloppyDriveType fd0);
>  
>  #define FW_CFG_IO_BASE     0x510
>  
> +/* port92.c */
>  #define PORT92_A20_LINE "a20"
>  
> +#define TYPE_PORT92 "port92"
> +
>  /* hpet.c */
>  extern int no_hpet;
>  
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 2e8992c7d0..15efcb29d5 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -733,119 +733,6 @@ void pc_cmos_init(PCMachineState *pcms,
>      qemu_register_reset(pc_cmos_init_late, &arg);
>  }
>  
> -#define TYPE_PORT92 "port92"
> -#define PORT92(obj) OBJECT_CHECK(Port92State, (obj), TYPE_PORT92)
> -
> -/* port 92 stuff: could be split off */
> -typedef struct Port92State {
> -    ISADevice parent_obj;
> -
> -    MemoryRegion io;
> -    uint8_t outport;
> -    qemu_irq a20_out;
> -} Port92State;
> -
> -static void port92_write(void *opaque, hwaddr addr, uint64_t val,
> -                         unsigned size)
> -{
> -    Port92State *s = opaque;
> -    int oldval = s->outport;
> -
> -    trace_port92_write(val);
> -    s->outport = val;
> -    qemu_set_irq(s->a20_out, (val >> 1) & 1);
> -    if ((val & 1) && !(oldval & 1)) {
> -        qemu_system_reset_request(SHUTDOWN_CAUSE_GUEST_RESET);
> -    }
> -}
> -
> -static uint64_t port92_read(void *opaque, hwaddr addr,
> -                            unsigned size)
> -{
> -    Port92State *s = opaque;
> -    uint32_t ret;
> -
> -    ret = s->outport;
> -    trace_port92_read(ret);
> -    return ret;
> -}
> -
> -static const VMStateDescription vmstate_port92_isa = {
> -    .name = "port92",
> -    .version_id = 1,
> -    .minimum_version_id = 1,
> -    .fields = (VMStateField[]) {
> -        VMSTATE_UINT8(outport, Port92State),
> -        VMSTATE_END_OF_LIST()
> -    }
> -};
> -
> -static void port92_reset(DeviceState *d)
> -{
> -    Port92State *s = PORT92(d);
> -
> -    s->outport &= ~1;
> -}
> -
> -static const MemoryRegionOps port92_ops = {
> -    .read = port92_read,
> -    .write = port92_write,
> -    .impl = {
> -        .min_access_size = 1,
> -        .max_access_size = 1,
> -    },
> -    .endianness = DEVICE_LITTLE_ENDIAN,
> -};
> -
> -static void port92_initfn(Object *obj)
> -{
> -    Port92State *s = PORT92(obj);
> -
> -    memory_region_init_io(&s->io, OBJECT(s), &port92_ops, s, "port92", 1);
> -
> -    s->outport = 0;
> -
> -    qdev_init_gpio_out_named(DEVICE(obj), &s->a20_out, PORT92_A20_LINE, 1);
> -}
> -
> -static void port92_realizefn(DeviceState *dev, Error **errp)
> -{
> -    ISADevice *isadev = ISA_DEVICE(dev);
> -    Port92State *s = PORT92(dev);
> -
> -    isa_register_ioport(isadev, &s->io, 0x92);
> -}
> -
> -static void port92_class_initfn(ObjectClass *klass, void *data)
> -{
> -    DeviceClass *dc = DEVICE_CLASS(klass);
> -
> -    dc->realize = port92_realizefn;
> -    dc->reset = port92_reset;
> -    dc->vmsd = &vmstate_port92_isa;
> -    /*
> -     * Reason: unlike ordinary ISA devices, this one needs additional
> -     * wiring: its A20 output line needs to be wired up with
> -     * qdev_connect_gpio_out_named().
> -     */
> -    dc->user_creatable = false;
> -}
> -
> -static const TypeInfo port92_info = {
> -    .name          = TYPE_PORT92,
> -    .parent        = TYPE_ISA_DEVICE,
> -    .instance_size = sizeof(Port92State),
> -    .instance_init = port92_initfn,
> -    .class_init    = port92_class_initfn,
> -};
> -
> -static void port92_register_types(void)
> -{
> -    type_register_static(&port92_info);
> -}
> -
> -type_init(port92_register_types)
> -
>  static void handle_a20_line_change(void *opaque, int irq, int level)
>  {
>      X86CPU *cpu = opaque;
> diff --git a/hw/i386/port92.c b/hw/i386/port92.c
> new file mode 100644
> index 0000000000..19866c44ef
> --- /dev/null
> +++ b/hw/i386/port92.c
> @@ -0,0 +1,126 @@
> +/*
> + * QEMU I/O port 0x92 (System Control Port A, to handle Fast Gate A20)
> + *
> + * Copyright (c) 2003-2004 Fabrice Bellard
> + *
> + * SPDX-License-Identifier: MIT
> + */
> +
> +#include "qemu/osdep.h"
> +#include "sysemu/runstate.h"
> +#include "migration/vmstate.h"
> +#include "hw/irq.h"
> +#include "hw/i386/pc.h"
> +#include "trace.h"
> +
> +#define PORT92(obj) OBJECT_CHECK(Port92State, (obj), TYPE_PORT92)
> +
> +typedef struct Port92State {
> +    ISADevice parent_obj;
> +
> +    MemoryRegion io;
> +    uint8_t outport;
> +    qemu_irq a20_out;
> +} Port92State;
> +
> +static void port92_write(void *opaque, hwaddr addr, uint64_t val,
> +                         unsigned size)
> +{
> +    Port92State *s = opaque;
> +    int oldval = s->outport;
> +
> +    trace_port92_write(val);
> +    s->outport = val;
> +    qemu_set_irq(s->a20_out, (val >> 1) & 1);
> +    if ((val & 1) && !(oldval & 1)) {
> +        qemu_system_reset_request(SHUTDOWN_CAUSE_GUEST_RESET);
> +    }
> +}
> +
> +static uint64_t port92_read(void *opaque, hwaddr addr,
> +                            unsigned size)
> +{
> +    Port92State *s = opaque;
> +    uint32_t ret;
> +
> +    ret = s->outport;
> +    trace_port92_read(ret);
> +
> +    return ret;
> +}
> +
> +static const VMStateDescription vmstate_port92_isa = {
> +    .name = "port92",
> +    .version_id = 1,
> +    .minimum_version_id = 1,
> +    .fields = (VMStateField[]) {
> +        VMSTATE_UINT8(outport, Port92State),
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> +
> +static void port92_reset(DeviceState *d)
> +{
> +    Port92State *s = PORT92(d);
> +
> +    s->outport &= ~1;
> +}
> +
> +static const MemoryRegionOps port92_ops = {
> +    .read = port92_read,
> +    .write = port92_write,
> +    .impl = {
> +        .min_access_size = 1,
> +        .max_access_size = 1,
> +    },
> +    .endianness = DEVICE_LITTLE_ENDIAN,
> +};
> +
> +static void port92_initfn(Object *obj)
> +{
> +    Port92State *s = PORT92(obj);
> +
> +    memory_region_init_io(&s->io, OBJECT(s), &port92_ops, s, "port92", 1);
> +
> +    s->outport = 0;
> +
> +    qdev_init_gpio_out_named(DEVICE(obj), &s->a20_out, PORT92_A20_LINE, 1);
> +}
> +
> +static void port92_realizefn(DeviceState *dev, Error **errp)
> +{
> +    ISADevice *isadev = ISA_DEVICE(dev);
> +    Port92State *s = PORT92(dev);
> +
> +    isa_register_ioport(isadev, &s->io, 0x92);
> +}
> +
> +static void port92_class_initfn(ObjectClass *klass, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +
> +    dc->realize = port92_realizefn;
> +    dc->reset = port92_reset;
> +    dc->vmsd = &vmstate_port92_isa;
> +    /*
> +     * Reason: unlike ordinary ISA devices, this one needs additional
> +     * wiring: its A20 output line needs to be wired up with
> +     * qdev_connect_gpio_out_named().
> +     */
> +    dc->user_creatable = false;
> +}
> +
> +static const TypeInfo port92_info = {
> +    .name          = TYPE_PORT92,
> +    .parent        = TYPE_ISA_DEVICE,
> +    .instance_size = sizeof(Port92State),
> +    .instance_init = port92_initfn,
> +    .class_init    = port92_class_initfn,
> +};
> +
> +static void port92_register_types(void)
> +{
> +    type_register_static(&port92_info);
> +}
> +
> +type_init(port92_register_types)
> diff --git a/hw/i386/Makefile.objs b/hw/i386/Makefile.objs
> index 0d195b5210..b317e7eee0 100644
> --- a/hw/i386/Makefile.objs
> +++ b/hw/i386/Makefile.objs
> @@ -12,6 +12,7 @@ obj-$(CONFIG_AMD_IOMMU) += amd_iommu.o
>  obj-$(CONFIG_XEN) += ../xenpv/ xen/
>  obj-$(CONFIG_VMPORT) += vmport.o
>  obj-$(CONFIG_VMMOUSE) += vmmouse.o
> +obj-$(CONFIG_PC) += port92.o
>  
>  obj-y += kvmvapic.o
>  obj-y += acpi-build.o
> diff --git a/hw/i386/trace-events b/hw/i386/trace-events
> index 43f33cf7e2..076ea5dcfb 100644
> --- a/hw/i386/trace-events
> +++ b/hw/i386/trace-events
> @@ -115,5 +115,7 @@ vmport_command(unsigned char command) "command: 0x%02x"
>  # pc.c
>  pc_gsi_interrupt(int irqn, int level) "GSI interrupt #%d level:%d"
>  pc_pic_interrupt(int irqn, int level) "PIC interrupt #%d level:%d"
> +
> +# port92.c
>  port92_read(uint8_t val) "port92: read 0x%02x"
>  port92_write(uint8_t val) "port92: write 0x%02x"
> 

Queued, thanks.

Paolo