[2/4] hw/i386/pc_sysfw: Alias rather than copy isa-bios region

Commit Message

Bernhard Beschow April 22, 2024, 8:06 p.m. UTC

In the -bios case the "isa-bios" memory region is an alias to the BIOS mapped
to the top of the 4G memory boundary. Do the same in the -pflash case to have
common behavior. This also makes pflash commands work in the "isa-bios" region
which some real-world legacy bioses rely on.

Note that in the sev_enabled() case, the "isa-bios" memory region in the -pflash
case will now also point to encrypted memory, just like it already does in the
-bios case.

Signed-off-by: Bernhard Beschow <[e-mail]>
---
 hw/i386/pc_sysfw.c | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

Patch

diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c
index 87b5bf59d6..6e89671c26 100644
--- a/hw/i386/pc_sysfw.c
+++ b/hw/i386/pc_sysfw.c
@@ -46,27 +46,18 @@  static void pc_isa_bios_init(MemoryRegion *rom_memory,
     int isa_bios_size;
     MemoryRegion *isa_bios;
     uint64_t flash_size;
-    void *flash_ptr, *isa_bios_ptr;
 
     flash_size = memory_region_size(flash_mem);
 
     /* map the last 128KB of the BIOS in ISA space */
     isa_bios_size = MIN(flash_size, 128 * KiB);
     isa_bios = g_malloc(sizeof(*isa_bios));
-    memory_region_init_ram(isa_bios, NULL, "isa-bios", isa_bios_size,
-                           &error_fatal);
+    memory_region_init_alias(isa_bios, NULL, "isa-bios", flash_mem,
+                             flash_size - isa_bios_size, isa_bios_size);
     memory_region_add_subregion_overlap(rom_memory,
                                         0x100000 - isa_bios_size,
                                         isa_bios,
                                         1);
-
-    /* copy ISA rom image from top of flash memory */
-    flash_ptr = memory_region_get_ram_ptr(flash_mem);
-    isa_bios_ptr = memory_region_get_ram_ptr(isa_bios);
-    memcpy(isa_bios_ptr,
-           ((uint8_t*)flash_ptr) + (flash_size - isa_bios_size),
-           isa_bios_size);
-
     memory_region_set_readonly(isa_bios, true);
 }