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vmgenid: replace x-write-pointer-available hack 

This compat property sole function is to prevent the device from being
instantiated. Instead of requiring an extra compat property, check if
fw_cfg has DMA enabled.

fw_cfg is a built-in device that is initialized very early by the
machine init code.  We have at least one other device that also
assumes fw_cfg_find() can be safely used on realize: pvpanic.

This has the additional benefit of handling other cases properly, like:

  $ qemu-system-x86_64 -device vmgenid -machine none
  qemu-system-x86_64: -device vmgenid: vmgenid requires DMA write support in fw_cfg, which this machine type does not provide
  $ qemu-system-x86_64 -device vmgenid -machine pc-i440fx-2.9 -global fw_cfg.dma_enabled=off
  qemu-system-x86_64: -device vmgenid: vmgenid requires DMA write support in fw_cfg, which this machine type does not provide
  $ qemu-system-x86_64 -device vmgenid -machine pc-i440fx-2.6 -global fw_cfg.dma_enabled=on
  [boots normally]

Suggested-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Ben Warren <ben@skyportsystems.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Marc-André Lureau 2017-08-07 18:45:13 +02:00 committed by Michael S. Tsirkin
parent 672339f7ef
commit c8389550de
5 changed files with 13 additions and 13 deletions
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10
hw/acpi/bios-linker-loader.c
View File

@ -168,6 +168,16 @@ bios_linker_find_file(const BIOSLinker *linker, const char *name)
return NULL;
}
/*
* board code must realize fw_cfg first, as a fixed device, before
* another device realize function call bios_linker_loader_can_write_pointer()
*/
bool bios_linker_loader_can_write_pointer(void)
{
FWCfgState *fw_cfg = fw_cfg_find();
return fw_cfg && fw_cfg_dma_enabled(fw_cfg);
}
/*
* bios_linker_loader_alloc: ask guest to load file into guest memory.
*

9
hw/acpi/vmgenid.c
View File

@ -205,17 +205,11 @@ static void vmgenid_handle_reset(void *opaque)
memset(vms->vmgenid_addr_le, 0, ARRAY_SIZE(vms->vmgenid_addr_le));
}
static Property vmgenid_properties[] = {
DEFINE_PROP_BOOL("x-write-pointer-available", VmGenIdState,
write_pointer_available, true),
DEFINE_PROP_END_OF_LIST(),
};
static void vmgenid_realize(DeviceState *dev, Error **errp)
{
VmGenIdState *vms = VMGENID(dev);
if (!vms->write_pointer_available) {
if (!bios_linker_loader_can_write_pointer()) {
error_setg(errp, "%s requires DMA write support in fw_cfg, "
"which this machine type does not provide", VMGENID_DEVICE);
return;
@ -239,7 +233,6 @@ static void vmgenid_device_class_init(ObjectClass *klass, void *data)
dc->vmsd = &vmstate_vmgenid;
dc->realize = vmgenid_realize;
dc->hotpluggable = false;
dc->props = vmgenid_properties;
set_bit(DEVICE_CATEGORY_MISC, dc->categories);
object_class_property_add_str(klass, VMGENID_GUID, NULL,

2
include/hw/acpi/bios-linker-loader.h
View File

@ -7,6 +7,8 @@ typedef struct BIOSLinker {
GArray *file_list;
} BIOSLinker;
bool bios_linker_loader_can_write_pointer(void);
BIOSLinker *bios_linker_loader_init(void);
void bios_linker_loader_alloc(BIOSLinker *linker,

1
include/hw/acpi/vmgenid.h
View File

@ -21,7 +21,6 @@ typedef struct VmGenIdState {
DeviceClass parent_obj;
QemuUUID guid; /* The 128-bit GUID seen by the guest */
uint8_t vmgenid_addr_le[8]; /* Address of the GUID (little-endian) */
bool write_pointer_available;
} VmGenIdState;
/* returns NULL unless there is exactly one device */

4
include/hw/compat.h
View File

@ -153,10 +153,6 @@
.driver = "fw_cfg_io",\
.property = "dma_enabled",\
.value = "off",\
},{\
.driver = "vmgenid",\
.property = "x-write-pointer-available",\
.value = "off",\
},
#define HW_COMPAT_2_3 \