Commit c8389550 authored by Marc-André Lureau's avatar Marc-André Lureau Committed by Michael S. Tsirkin
Browse files

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: default avatarEduardo Habkost <ehabkost@redhat.com>
Signed-off-by: default avatarMarc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: default avatarEduardo Habkost <ehabkost@redhat.com>
Reviewed-by: default avatarBen Warren <ben@skyportsystems.com>
Reviewed-by: default avatarLaszlo Ersek <lersek@redhat.com>
Reviewed-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 672339f7

hw/acpi/bios-linker-loader.c

+10 −0
Original line number Diff line number Diff line
@@ -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.

 *

hw/acpi/vmgenid.c

+1 −8
Original line number Diff line number Diff line
@@ -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,

include/hw/acpi/bios-linker-loader.h

+2 −0
Original line number Diff line number Diff line
@@ -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,

include/hw/acpi/vmgenid.h

+0 −1
Original line number Diff line number Diff line
@@ -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 */

include/hw/compat.h

+0 −4
Original line number Diff line number Diff line
@@ -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 \