hw/i386: Assume fw_cfg DMA is always enabled

Now all calls of x86 machines to fw_cfg_init_io_dma() pass DMA
arguments, so the FWCfgState (FWCfgIoState) created by x86 machines
enables DMA by default.

Although other callers of fw_cfg_init_io_dma() besides x86 also pass
DMA arguments to create DMA-enabled FwCfgIoState, the "dma_enabled"
property of FwCfgIoState cannot yet be removed, because Sun4u and Sun4v
still create DMA-disabled FwCfgIoState (bypass fw_cfg_init_io_dma()) in
sun4uv_init() (hw/sparc64/sun4u.c).

Maybe reusing fw_cfg_init_io_dma() for them would be a better choice, or
adding fw_cfg_init_io_nodma(). However, before that, first simplify the
handling of FwCfgState in x86.

Considering that FwCfgIoState in x86 enables DMA by default, remove the
handling for DMA-disabled cases and replace DMA checks with assertions
to ensure that the default DMA-enabled setting is not broken.

Then 'linuxboot.bin' isn't used anymore, and it will be removed in the
next commit.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Acked-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Link: https://lore.kernel.org/r/20260108033051.777361-15-zhao1.liu@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

hw/i386/fw_cfg.c

@@ -215,18 +215,18 @@ void fw_cfg_build_feature_control(MachineState *ms, FWCfgState *fw_cfg)
 #ifdef CONFIG_ACPI
 void fw_cfg_add_acpi_dsdt(Aml *scope, FWCfgState *fw_cfg)
 {
+    uint8_t io_size;
+    Aml *dev = aml_device("FWCF");
+    Aml *crs = aml_resource_template();
+
     /*
      * when using port i/o, the 8-bit data register *always* overlaps
      * with half of the 16-bit control register. Hence, the total size
-     * of the i/o region used is FW_CFG_CTL_SIZE; when using DMA, the
-     * DMA control register is located at FW_CFG_DMA_IO_BASE + 4
+     * of the i/o region used is FW_CFG_CTL_SIZE; And the DMA control
+     * register is located at FW_CFG_DMA_IO_BASE + 4
      */
-    Object *obj = OBJECT(fw_cfg);
-    uint8_t io_size = object_property_get_bool(obj, "dma_enabled", NULL) ?
-        ROUND_UP(FW_CFG_CTL_SIZE, 4) + sizeof(dma_addr_t) :
-        FW_CFG_CTL_SIZE;
-    Aml *dev = aml_device("FWCF");
-    Aml *crs = aml_resource_template();
+    assert(fw_cfg_dma_enabled(fw_cfg));
+    io_size = ROUND_UP(FW_CFG_CTL_SIZE, 4) + sizeof(dma_addr_t);
 
     aml_append(dev, aml_name_decl("_HID", aml_string("QEMU0002")));
 

hw/i386/x86-common.c

@@ -1002,10 +1002,8 @@ void x86_load_linux(X86MachineState *x86ms,
     }
 
     option_rom[nb_option_roms].bootindex = 0;
-    option_rom[nb_option_roms].name = "linuxboot.bin";
-    if (fw_cfg_dma_enabled(fw_cfg)) {
-        option_rom[nb_option_roms].name = "linuxboot_dma.bin";
-    }
+    assert(fw_cfg_dma_enabled(fw_cfg));
+    option_rom[nb_option_roms].name = "linuxboot_dma.bin";
     nb_option_roms++;
 }