Re: [Qemu-devel] [PATCH 2/5] acpi_piix4: Only allow writes to PCI hotplug eject register

[Igor Mammedov]

On 04/05/2012 07:51 AM, Alex Williamson wrote:

This is never read.  We can also derive bus from the write handler,
making this more inline with the other callbacks.  Note that
pciej_write was actually called with (PCIBus *)dev->bus, which is
cast as a void* allowing us to pretend it's a BusState*.  Fix this
so we don't depend on the BusState location within PCIBus.

Signed-off-by: Alex Williamson<alex.william...@redhat.com>
---

  docs/specs/acpi_pci_hotplug.txt |    2 +-
  hw/acpi_piix4.c                 |   14 ++++----------
  2 files changed, 5 insertions(+), 11 deletions(-)

diff --git a/docs/specs/acpi_pci_hotplug.txt b/docs/specs/acpi_pci_hotplug.txt
index 1e2c8a2..1e61d19 100644
--- a/docs/specs/acpi_pci_hotplug.txt
+++ b/docs/specs/acpi_pci_hotplug.txt
@@ -28,7 +28,7 @@ PCI device eject (IO port 0xae08-0xae0b, 4-byte access):
  ----------------------------------------

  Used by ACPI BIOS _EJ0 method to request device removal. One bit per slot.
-Reads return 0.
+Read-only.

Write-only perhaps?

  PCI removability status (IO port 0xae0c-0xae0f, 4-byte access):
  -----------------------------------------------
diff --git a/hw/acpi_piix4.c b/hw/acpi_piix4.c
index 44d1423..6ee832a 100644
--- a/hw/acpi_piix4.c
+++ b/hw/acpi_piix4.c
@@ -487,15 +487,11 @@ static uint32_t pci_down_read(void *opaque, uint32_t addr)
      return val;
  }

-static uint32_t pciej_read(void *opaque, uint32_t addr)
-{
-    PIIX4_DPRINTF("pciej read %x\n", addr);
-    return 0;
-}
-

what will happen if bios tries to read from reg?

  static void pciej_write(void *opaque, uint32_t addr, uint32_t val)
  {
-    BusState *bus = opaque;
+    PIIX4PMState *s = opaque;
+    PCIDevice *dev =&s->dev;
+    BusState *bus = qdev_get_parent_bus(&dev->qdev);
      DeviceState *qdev, *next;
      int slot = ffs(val) - 1;

@@ -507,7 +503,6 @@ static void pciej_write(void *opaque, uint32_t addr, 
uint32_t val)
          }
      }

-
      PIIX4_DPRINTF("pciej write %x<== %d\n", addr, val);
  }

@@ -547,8 +542,7 @@ static void piix4_acpi_system_hot_add_init(PCIBus *bus, 
PIIX4PMState *s)
      register_ioport_read(PCI_UP_BASE, 4, 4, pci_up_read, s);
      register_ioport_read(PCI_DOWN_BASE, 4, 4, pci_down_read, s);

-    register_ioport_write(PCI_EJ_BASE, 4, 4, pciej_write, bus);
-    register_ioport_read(PCI_EJ_BASE, 4, 4,  pciej_read, bus);
+    register_ioport_write(PCI_EJ_BASE, 4, 4, pciej_write, s);

      register_ioport_write(PCI_RMV_BASE, 4, 4, pcirmv_write, s);
      register_ioport_read(PCI_RMV_BASE, 4, 4,  pcirmv_read, s);

--
-----
 Igor