target/i386: use DMA-enabled multiboot ROM for new-enough QEMU machine types

As long as fw_cfg supports DMA, the new ROM can be used also on older
machine types because it has the same size as the existing one.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

hw/i386/multiboot.c

@@ -143,7 +143,8 @@ static void mb_add_mod(MultibootState *s,
     s->mb_mods_count++;
 }
 
-int load_multiboot(FWCfgState *fw_cfg,
+int load_multiboot(X86MachineState *x86ms,
+                   FWCfgState *fw_cfg,
                    FILE *f,
                    const char *kernel_filename,
                    const char *initrd_filename,
@@ -151,6 +152,7 @@ int load_multiboot(FWCfgState *fw_cfg,
                    int kernel_file_size,
                    uint8_t *header)
 {
+    bool multiboot_dma_enabled = X86_MACHINE_GET_CLASS(x86ms)->fwcfg_dma_enabled;
     int i, is_multiboot = 0;
     uint32_t flags = 0;
     uint32_t mh_entry_addr;
@@ -401,7 +403,11 @@ int load_multiboot(FWCfgState *fw_cfg,
     fw_cfg_add_bytes(fw_cfg, FW_CFG_INITRD_DATA, mb_bootinfo_data,
                      sizeof(bootinfo));
 
-    option_rom[nb_option_roms].name = "multiboot.bin";
+    if (multiboot_dma_enabled) {
+        option_rom[nb_option_roms].name = "multiboot_dma.bin";
+    } else {
+        option_rom[nb_option_roms].name = "multiboot.bin";
+    }
     option_rom[nb_option_roms].bootindex = 0;
     nb_option_roms++;
 

hw/i386/multiboot.h

@@ -2,8 +2,10 @@
 #define QEMU_MULTIBOOT_H
 
 #include "hw/nvram/fw_cfg.h"
+#include "hw/i386/x86.h"
 
-int load_multiboot(FWCfgState *fw_cfg,
+int load_multiboot(X86MachineState *x86ms,
+                   FWCfgState *fw_cfg,
                    FILE *f,
                    const char *kernel_filename,
                    const char *initrd_filename,

hw/i386/pc.c

@@ -780,7 +780,8 @@ void xen_load_linux(PCMachineState *pcms)
         assert(!strcmp(option_rom[i].name, "linuxboot.bin") ||
                !strcmp(option_rom[i].name, "linuxboot_dma.bin") ||
                !strcmp(option_rom[i].name, "pvh.bin") ||
-               !strcmp(option_rom[i].name, "multiboot.bin"));
+               !strcmp(option_rom[i].name, "multiboot.bin") ||
+               !strcmp(option_rom[i].name, "multiboot_dma.bin"));
         rom_add_option(option_rom[i].name, option_rom[i].bootindex);
     }
     x86ms->fw_cfg = fw_cfg;

hw/i386/x86.c

@@ -814,7 +814,7 @@ void x86_load_linux(X86MachineState *x86ms,
          * PVH), so we try multiboot first since we check the multiboot magic
          * header before to load it.
          */
-        if (load_multiboot(fw_cfg, f, kernel_filename, initrd_filename,
+        if (load_multiboot(x86ms, fw_cfg, f, kernel_filename, initrd_filename,
                            kernel_cmdline, kernel_size, header)) {
             return;
         }